Discussion:
Humidifier - Hot vs Cold Water Experiment
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t***@optonline.net
2009-02-11 16:12:38 UTC
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For those of you that followed any of the discussions here about
whether using hot water versus cold water in a furnace humidifier
makes a difference in the amount of water that evaporates, I did the
actual test on my unit. Here's exactly how I did it and the results.

The unit is an Aprilaire 700A installed on a gas forced air furnace.
To do the test, I made sure to keep everything constant except the
incoming water temp. My unit is connected to hot water, so to change
the water temp, I turned off the water heater and used up the hot
water through normal household use. I got the hot water tank temp
down to 51F. The house humidity was 37% at the time of the test and
the temp was 67F. I routed the humdifier drain hose to a location
that I could put a gallon container under it and remove it without
disturbing the hose. I placed a temporary container under the running
hose to catch the water. I then started the furnace with the
humidifier set high enough to be running constantly. I let the
system stabilize for 5 mins to get to a steady-state. Then I quickly
replaced the temporary container with another empty gallon container
and started a stop watch. During the 5 min period, I also measured
the temp of the water exiting the drain hose. At precisely 5 mins, I
removed the container and used a measuring cup to determine the volume
of water. I also shut down the furnace.

Then, I fired the water heater back up and let it run to get the water
temp to a higher temp to see what happens with medium temp warm
water. I then turned the water heater off again. That temp turned
out to be 102F. I then repeated the process of starting the furnace,
letting it run for 5 mins to stabilize, then measuring the drain water
output for another 5 minutes. Next, I fired the water heater up
again and allowed it to come up to normal temperture. And again, I
turned on the furnace, let it stabilize for 5 mins, then measured the
water output for 5 mins.

Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.

Here are the results:


Temp Water collected in 5 mins Temp of Water Exiting Drain Hose

51F 66.5 Oz 78.4F

102 61.5 78.0

135 58.0 79.2


Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow: 73.0 Oz



Now, doing the math, the amount of water evaporated during the 5 mins:


51F 73 - 66.5 = 6.5 Oz

102 73 - 61.5 = 11.5

135 73 - 58.0 = 15.0


Using hot water more than doubled the output. Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water. Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.

So, there you have it folks. This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
HeyBub
2009-02-11 16:31:25 UTC
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Post by t***@optonline.net
For those of you that followed any of the discussions here about
whether using hot water versus cold water in a furnace humidifier
makes a difference in the amount of water that evaporates, I did the
actual test on my unit. Here's exactly how I did it and the results.
The unit is an Aprilaire 700A installed on a gas forced air furnace.
To do the test, I made sure to keep everything constant except the
incoming water temp. My unit is connected to hot water, so to change
the water temp, I turned off the water heater and used up the hot
water through normal household use. I got the hot water tank temp
down to 51F. The house humidity was 37% at the time of the test and
the temp was 67F. I routed the humdifier drain hose to a location
that I could put a gallon container under it and remove it without
disturbing the hose. I placed a temporary container under the running
hose to catch the water. I then started the furnace with the
humidifier set high enough to be running constantly. I let the
system stabilize for 5 mins to get to a steady-state. Then I quickly
replaced the temporary container with another empty gallon container
and started a stop watch. During the 5 min period, I also measured
the temp of the water exiting the drain hose. At precisely 5 mins, I
removed the container and used a measuring cup to determine the volume
of water. I also shut down the furnace.
Then, I fired the water heater back up and let it run to get the water
temp to a higher temp to see what happens with medium temp warm
water. I then turned the water heater off again. That temp turned
out to be 102F. I then repeated the process of starting the furnace,
letting it run for 5 mins to stabilize, then measuring the drain water
output for another 5 minutes. Next, I fired the water heater up
again and allowed it to come up to normal temperture. And again, I
turned on the furnace, let it stabilize for 5 mins, then measured the
water output for 5 mins.
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp Water collected in 5 mins Temp of Water Exiting Drain Hose
51F 66.5 Oz 78.4F
102 61.5 78.0
135 58.0 79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow: 73.0 Oz
51F 73 - 66.5 = 6.5 Oz
102 73 - 61.5 = 11.5
135 73 - 58.0 = 15.0
Using hot water more than doubled the output. Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water. Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
So, there you have it folks. This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
Thanks for the quantification. Though I think the basic question - does hot
water evaporate more quickly than cold - was settled about ~60,000 B.C. with
the taming of fire.
Smarty
2009-02-11 17:57:40 UTC
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Heybub,

Thanks for posting this. As I reported in a very early reply on this
subject, my humidity shot up very dramatically when I followed Aprilaire's
suggestion to use hot water. The difference was extremely noticeable and
measureable with both my humidistat and the use of a separate instrument.

I was totally astonished when a (self-proclaimed) HVAC expert of 30 years
disagreed, and said that it would make no difference.

I'm glad to see that your measurements confirm my own experiences here.

Smarty
Post by HeyBub
Post by t***@optonline.net
For those of you that followed any of the discussions here about
whether using hot water versus cold water in a furnace humidifier
makes a difference in the amount of water that evaporates, I did the
actual test on my unit. Here's exactly how I did it and the results.
The unit is an Aprilaire 700A installed on a gas forced air furnace.
To do the test, I made sure to keep everything constant except the
incoming water temp. My unit is connected to hot water, so to change
the water temp, I turned off the water heater and used up the hot
water through normal household use. I got the hot water tank temp
down to 51F. The house humidity was 37% at the time of the test and
the temp was 67F. I routed the humdifier drain hose to a location
that I could put a gallon container under it and remove it without
disturbing the hose. I placed a temporary container under the running
hose to catch the water. I then started the furnace with the
humidifier set high enough to be running constantly. I let the
system stabilize for 5 mins to get to a steady-state. Then I quickly
replaced the temporary container with another empty gallon container
and started a stop watch. During the 5 min period, I also measured
the temp of the water exiting the drain hose. At precisely 5 mins, I
removed the container and used a measuring cup to determine the volume
of water. I also shut down the furnace.
Then, I fired the water heater back up and let it run to get the water
temp to a higher temp to see what happens with medium temp warm
water. I then turned the water heater off again. That temp turned
out to be 102F. I then repeated the process of starting the furnace,
letting it run for 5 mins to stabilize, then measuring the drain water
output for another 5 minutes. Next, I fired the water heater up
again and allowed it to come up to normal temperture. And again, I
turned on the furnace, let it stabilize for 5 mins, then measured the
water output for 5 mins.
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp Water collected in 5 mins Temp of Water Exiting Drain Hose
51F 66.5 Oz 78.4F
102 61.5 78.0
135 58.0 79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow: 73.0 Oz
51F 73 - 66.5 = 6.5 Oz
102 73 - 61.5 = 11.5
135 73 - 58.0 = 15.0
Using hot water more than doubled the output. Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water. Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
So, there you have it folks. This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
Thanks for the quantification. Though I think the basic question - does
hot water evaporate more quickly than cold - was settled about ~60,000
B.C. with the taming of fire.
Tony Hwang
2009-02-13 01:25:35 UTC
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Post by Smarty
Heybub,
Thanks for posting this. As I reported in a very early reply on this
subject, my humidity shot up very dramatically when I followed
Aprilaire's suggestion to use hot water. The difference was extremely
noticeable and measureable with both my humidistat and the use of a
separate instrument.
I was totally astonished when a (self-proclaimed) HVAC expert of 30
years disagreed, and said that it would make no difference.
I'm glad to see that your measurements confirm my own experiences here.
Smarty
Post by HeyBub
Post by t***@optonline.net
For those of you that followed any of the discussions here about
whether using hot water versus cold water in a furnace humidifier
makes a difference in the amount of water that evaporates, I did the
actual test on my unit. Here's exactly how I did it and the results.
The unit is an Aprilaire 700A installed on a gas forced air furnace.
To do the test, I made sure to keep everything constant except the
incoming water temp. My unit is connected to hot water, so to change
the water temp, I turned off the water heater and used up the hot
water through normal household use. I got the hot water tank temp
down to 51F. The house humidity was 37% at the time of the test and
the temp was 67F. I routed the humdifier drain hose to a location
that I could put a gallon container under it and remove it without
disturbing the hose. I placed a temporary container under the running
hose to catch the water. I then started the furnace with the
humidifier set high enough to be running constantly. I let the
system stabilize for 5 mins to get to a steady-state. Then I quickly
replaced the temporary container with another empty gallon container
and started a stop watch. During the 5 min period, I also measured
the temp of the water exiting the drain hose. At precisely 5 mins, I
removed the container and used a measuring cup to determine the volume
of water. I also shut down the furnace.
Then, I fired the water heater back up and let it run to get the water
temp to a higher temp to see what happens with medium temp warm
water. I then turned the water heater off again. That temp turned
out to be 102F. I then repeated the process of starting the furnace,
letting it run for 5 mins to stabilize, then measuring the drain water
output for another 5 minutes. Next, I fired the water heater up
again and allowed it to come up to normal temperture. And again, I
turned on the furnace, let it stabilize for 5 mins, then measured the
water output for 5 mins.
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp Water collected in 5 mins Temp of Water Exiting Drain Hose
51F 66.5 Oz 78.4F
102 61.5 78.0
135 58.0 79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow: 73.0 Oz
51F 73 - 66.5 = 6.5 Oz
102 73 - 61.5 = 11.5
135 73 - 58.0 = 15.0
Using hot water more than doubled the output. Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water. Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
So, there you have it folks. This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
Achieving the desired set humidity. Using cold water humidity in the
house is properly maintained during winter month. Also using Aprilaire
humidifier here.
Post by Smarty
Post by HeyBub
Thanks for the quantification. Though I think the basic question -
does hot water evaporate more quickly than cold - was settled about
~60,000 B.C. with the taming of fire.
Chet
2009-02-11 19:30:02 UTC
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Edited
">
Though I think the basic question - does hot water evaporate more quickly
than cold - was settled about ~60,000 B.C. with the taming of fire.
Don't get technical :)

People love to argue over this and over whether warm water will freeze
quicker than cold water.

They need to have their fun.


Chet
HeyBub
2009-02-11 19:41:39 UTC
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Post by Chet
Edited
">
Though I think the basic question - does hot water evaporate more
quickly than cold - was settled about ~60,000 B.C. with the taming
of fire.
Don't get technical :)
People love to argue over this and over whether warm water will freeze
quicker than cold water.
They need to have their fun.
Well, there is SOME experience behind hot water freezing faster than cold.

In the pre-written-word days of refrigerators, placing a tray of hot water
in the freezing compartment would melt the frost, allowing the ice tray to
get closer, if not directly on, the cooling coils. Just sitting on an inch
of frost was a fair insulator.

Now here's an interesting question: which boils faster, tap water or
distilled water? And which freezes faster?
Jim Elbrecht
2009-02-11 16:52:43 UTC
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On Wed, 11 Feb 2009 08:12:38 -0800 (PST), ***@optonline.net wrote:


-snip-
Post by t***@optonline.net
So, there you have it folks. This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
Well done-- This is one of those deals where I *knew* the right
answer, but was surprised with how *much* difference it makes.

I'm still procrastinating on putting a bucket under the output hose to
see how much water actually gets past the water panel.

Speaking of which- I changed mine today because groundhog day is about
midwinter in my part of the world. The old panel didn't look any
different than the new one to my untrained eyes. There is a little
lime on the outlet tray- but otherwise it looks new. Do most folks
follow the Aprilaire directions and change the water panels twice a
year?

Jim
Frank
2009-02-11 18:44:04 UTC
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Post by t***@optonline.net
For those of you that followed any of the discussions here about
whether using hot water versus cold water in a furnace humidifier
makes a difference in the amount of water that evaporates, I did the
actual test on my unit. Here's exactly how I did it and the results.
The unit is an Aprilaire 700A installed on a gas forced air furnace.
To do the test, I made sure to keep everything constant except the
incoming water temp. My unit is connected to hot water, so to change
the water temp, I turned off the water heater and used up the hot
water through normal household use. I got the hot water tank temp
down to 51F. The house humidity was 37% at the time of the test and
the temp was 67F. I routed the humdifier drain hose to a location
that I could put a gallon container under it and remove it without
disturbing the hose. I placed a temporary container under the running
hose to catch the water. I then started the furnace with the
humidifier set high enough to be running constantly. I let the
system stabilize for 5 mins to get to a steady-state. Then I quickly
replaced the temporary container with another empty gallon container
and started a stop watch. During the 5 min period, I also measured
the temp of the water exiting the drain hose. At precisely 5 mins, I
removed the container and used a measuring cup to determine the volume
of water. I also shut down the furnace.
Then, I fired the water heater back up and let it run to get the water
temp to a higher temp to see what happens with medium temp warm
water. I then turned the water heater off again. That temp turned
out to be 102F. I then repeated the process of starting the furnace,
letting it run for 5 mins to stabilize, then measuring the drain water
output for another 5 minutes. Next, I fired the water heater up
again and allowed it to come up to normal temperture. And again, I
turned on the furnace, let it stabilize for 5 mins, then measured the
water output for 5 mins.
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp Water collected in 5 mins Temp of Water Exiting Drain Hose
51F 66.5 Oz 78.4F
102 61.5 78.0
135 58.0 79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow: 73.0 Oz
51F 73 - 66.5 = 6.5 Oz
102 73 - 61.5 = 11.5
135 73 - 58.0 = 15.0
Using hot water more than doubled the output. Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water. Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
So, there you have it folks. This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
Interesting result but thermodynamically increasing one gram of water
from 51 to 135 deg F only takes 23 calories of heat while converting the
one gram of water to vapor at 212 deg F takes 540 calories.

One would expect a smaller difference in your results so there must be
other factors involved. Without doing the detailed math, I would have
guessed no more than 5% improvement.

I'm also surprised that the Aprilaire uses about 10 gal of water/hour.
My French drain under the outlet is always wet but does not flood and I
have no sump pump.

Humidity in house is fine so I would not bother to use warm water in
mine. All I do is change the medium once a year.
dpb
2009-02-11 19:31:57 UTC
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***@optonline.net wrote:
...
Post by t***@optonline.net
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp Water collected in 5 mins Temp of Water Exiting Drain Hose
51F 66.5 Oz 78.4F
102 61.5 78.0
135 58.0 79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow: 73.0 Oz
51F 73 - 66.5 = 6.5 Oz
102 73 - 61.5 = 11.5
135 73 - 58.0 = 15.0
Using hot water more than doubled the output. Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water. Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
...

Hmmm....along w/ Frank I'm puzzled by the apparent paradox in the
thermodynamics here.

My first question would have to do w/ whether the assumption of constant
input flow rate is valid not knowing the Aprilaire at all. Secondly the
exit temperatures seem puzzling.

Would take knowing and/or learning far more about the specifics of the
Aprilaire and the installation and the experiment than I care to
quantify the results, however... :)

--
t***@optonline.net
2009-02-11 20:05:17 UTC
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Post by dpb
...
Post by t***@optonline.net
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp     Water collected in 5 mins    Temp of Water Exiting Drain Hose
 51F        66.5 Oz                                  78.4F
102         61.5                                     78.0
135         58.0                                     79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow:   73.0 Oz
 51F    73 - 66.5 =  6.5 Oz
102     73 - 61.5 = 11.5
135     73 - 58.0 = 15.0
Using hot water more than doubled the output.  Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water.     Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
...
Hmmm....along w/ Frank I'm puzzled by the apparent paradox in the
thermodynamics here.
My first question would have to do w/ whether the assumption of constant
input flow rate is valid not knowing the Aprilaire at all.  Secondly the
exit temperatures seem puzzling.
The flow rate is determined by the water pressure and by an orifice
with a small hole at the solenoid valve. It's hard to imagine that
hot water would flow at a slower rate through it, which is what would
be needed to skew the results.

What's puzzling about the exit temps? They are for practical
purposes all the same. Which is what one would expect. If you start
with cold water, then the water temp rises on it's way down the
panel. If it's hot water, it cools on it's way down. Either way,
with a lot of air blowing on the panel, it seems reasonable that it
reaches a final temp somewhere before the end of the panel.

The only thing that is a little surprising to me is the amount of
difference hot vs cold made. I would have thought that there could be
a 25 to 50% difference. I think it has to do with the fact that
evaporation in this case is a complex process, not entirely described
by latent heat. All you have to do is have the air moving by catch
some of the higher energy particles that are trying to escape the
surface tension of the water.
Post by dpb
Would take knowing and/or learning far more about the specifics of the
Aprilaire and the installation and the experiment than I care to
quantify the results, however... :)
It's essentially a panel with max surface area, through which air
flows. It's fed by a water pipe that has a solenoid valve and a
small orifice to meter the water flow.
Post by dpb
--- Hide quoted text -
- Show quoted text -
dpb
2009-02-11 21:30:05 UTC
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...
Post by t***@optonline.net
Post by dpb
Hmmm....along w/ Frank I'm puzzled by the apparent paradox in the
thermodynamics here.
My first question would have to do w/ whether the assumption of constant
input flow rate is valid not knowing the Aprilaire at all. Secondly the
exit temperatures seem puzzling.
The flow rate is determined by the water pressure and by an orifice
with a small hole at the solenoid valve. It's hard to imagine that
hot water would flow at a slower rate through it, which is what would
be needed to skew the results.
I was commenting simply on the design of the experiment is extremely
sensitive to the assumption that that is indeed a constant. As noted, I
have no knowledge of the device itself, so if there were a float or
somesuch, it's a possibility that the lower evaporation rates influence
the inlet volumes.
Post by t***@optonline.net
What's puzzling about the exit temps? They are for practical
purposes all the same. Which is what one would expect. If you start
with cold water, then the water temp rises on it's way down the
panel. If it's hot water, it cools on it's way down. Either way,
with a lot of air blowing on the panel, it seems reasonable that it
reaches a final temp somewhere before the end of the panel.
Again, that is dependent on details I'm unaware of...if there's
sufficient time/distance for a secondary heat transfer to occur then it
really is a case of the red herring in the data--it has no really
bearing on the experiment. Again, just commenting...
Post by t***@optonline.net
The only thing that is a little surprising to me is the amount of
difference hot vs cold made. I would have thought that there could be
a 25 to 50% difference. I think it has to do with the fact that
evaporation in this case is a complex process, not entirely described
by latent heat. ...
I had the "aha!" moment shortly after I posted and was coming back to
amplify and, I think, answer the "why" question.

Looked up water vapor pressure as a function of temperature. The
results you got and the vapor pressure and some derived values that will
discuss on down are as follows. You can see the vapor pressure is quite
sensitive to temperature as was your evaporation rate.

Normalized to 51F Normalized to 51F
T(F) Evap(oz) VP(mm Hg) Evap VP VP**3
51 6.5 9.5 1.0 1.0 1.0
102 11.5 52 5.5 1.8 5.5
135 15.0 130 13.7 2.3 12.2

Assuming there's more than adequate heat available to evaporate the
water, the problem is one of residence time and heat transfer. My
conjecture is the vapor pressure is key in atomizing and thereby
increasing the effective heat transfer (and probably also increasing the
residence time some, to boot).

The normalized columns show the relative effectiveness of the
evaporation as compared to the cold water as the temperature was raised
(again, assuming there isn't any major bias in the experiment which I'm
willing to accept is probably not too bad given the orifice as a rate
controller for the key variable of input). It shows the effective
evaporation went up by an even faster rate than the vapor pressure.

But interestingly enough, the magnitude of the numbers caught my eye and
I just guessed at a power law exponent of 3 and voila! -- the agreement
is quite nice...

I think this is the basis for underlying the phenomenon.

I didn't look for engineering correlations for predictions of
evaporative rates, but they undoubtedly exist and Perry's Handbook would
be a reasonable place to start. It would be interesting to see if such
correlations did follow a power law but I'm not inclined to pursue it
further to see--I really don't know why I got in before (other than the
single measurement sensitivity in the experiment caught my eye being a
thing I was heavily involved in in many real situations in an earlier life).

Anyway, maybe that will add some cannons to the fodder... :)

--
m***@yahoo.com
2009-02-11 22:34:20 UTC
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Post by t***@optonline.net
Post by dpb
...
Post by t***@optonline.net
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp     Water collected in 5 mins    Temp of Water Exiting Drain Hose
 51F        66.5 Oz                                  78.4F
102         61.5                                     78.0
135         58.0                                     79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow:   73.0 Oz
 51F    73 - 66.5 =  6.5 Oz
102     73 - 61.5 = 11.5
135     73 - 58.0 = 15.0
Using hot water more than doubled the output.  Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water.     Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
...
Hmmm....along w/ Frank I'm puzzled by the apparent paradox in the
thermodynamics here.
My first question would have to do w/ whether the assumption of constant
input flow rate is valid not knowing the Aprilaire at all.  Secondly the
exit temperatures seem puzzling.
The flow rate is determined by the water pressure and by an orifice
with a small hole at the solenoid valve.   It's hard to imagine that
hot water would flow at a slower rate through it, which is what would
be needed to skew the results.
What's puzzling about the exit temps?   They are for practical
purposes all the same.  Which is what one would expect.  If you start
with cold water, then the water temp rises on it's way down the
panel.  If it's hot water, it cools on it's way down.  Either way,
with a lot of air blowing on the panel, it seems reasonable that it
reaches a final temp somewhere before the end of the panel.
The only thing that is a little surprising to me is the amount of
difference hot vs cold made.  I would have thought that there could be
a 25 to 50% difference.  I think it has to do with the fact that
evaporation in this case is a complex process, not entirely described
by latent heat.   All you have to do is have the air moving by catch
some of the higher energy particles that are trying to escape the
surface tension of the water.
Post by dpb
Would take knowing and/or learning far more about the specifics of the
Aprilaire and the installation and the experiment than I care to
quantify the results, however... :)
It's essentially a panel with max surface area, through which air
flows.   It's fed by a water pipe that has a solenoid valve and a
small orifice to meter the water flow.
Post by dpb
--- Hide quoted text -
- Show quoted text -- Hide quoted text -
- Show quoted text -- Hide quoted text -
- Show quoted text -
Hi Trad...

nice job...

But I have the same questions as Frank and dpd..

1)The outlet water temperatues are almost the same so you have to
agree that when the water temp is the same the evap rate is the same.
So for at least part of the panal, the water temp and evap rates are
about the same. In order for the overall evap rates to change by 2x,
there has to be a large portion of water panel with a large temp
diff.

2) I agree with the other poster, you assumed that the inflow is 73
and equal in all 3 cases. It seems logical but even if there is a
small change in the inflow rate, it will make a big error in the
results. I could imagine that hot water might not flow through an
orfice the same as cold, but I don't really know.

3) I am surprised that the flow through rate is so high. For every 1
galllon that is evaporated about 5 to 10 gallons go down the drain. I
was expecting the flow through rate to be more like 2 gallons in , 1
gallon out and 1 gallon evap. The longer the water is in the
humidifer, then the less difference the inlet temp would make.... If
the water flows quickly right through then I can see why hot inlet
water might be more significant, but then the outlet temps would not
be the same so I don't know...??????

4) Whats the air temp from the furnace that is flowing by the water?

If you verify that the inlet water rates are really 73 in all three
cases, I will be willing to concede...

(and I thank everyone for keeping this discussion civil)

Mark
t***@optonline.net
2009-02-12 14:29:14 UTC
Permalink
Raw Message
Post by m***@yahoo.com
Post by t***@optonline.net
Post by dpb
...
Post by t***@optonline.net
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp     Water collected in 5 mins    Temp of Water Exiting Drain Hose
 51F        66.5 Oz                                  78.4F
102         61.5                                     78.0
135         58.0                                     79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow:   73.0 Oz
 51F    73 - 66.5 =  6.5 Oz
102     73 - 61.5 = 11.5
135     73 - 58.0 = 15.0
Using hot water more than doubled the output.  Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water.     Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
...
Hmmm....along w/ Frank I'm puzzled by the apparent paradox in the
thermodynamics here.
My first question would have to do w/ whether the assumption of constant
input flow rate is valid not knowing the Aprilaire at all.  Secondly the
exit temperatures seem puzzling.
The flow rate is determined by the water pressure and by an orifice
with a small hole at the solenoid valve.   It's hard to imagine that
hot water would flow at a slower rate through it, which is what would
be needed to skew the results.
What's puzzling about the exit temps?   They are for practical
purposes all the same.  Which is what one would expect.  If you start
with cold water, then the water temp rises on it's way down the
panel.  If it's hot water, it cools on it's way down.  Either way,
with a lot of air blowing on the panel, it seems reasonable that it
reaches a final temp somewhere before the end of the panel.
The only thing that is a little surprising to me is the amount of
difference hot vs cold made.  I would have thought that there could be
a 25 to 50% difference.  I think it has to do with the fact that
evaporation in this case is a complex process, not entirely described
by latent heat.   All you have to do is have the air moving by catch
some of the higher energy particles that are trying to escape the
surface tension of the water.
Post by dpb
Would take knowing and/or learning far more about the specifics of the
Aprilaire and the installation and the experiment than I care to
quantify the results, however... :)
It's essentially a panel with max surface area, through which air
flows.   It's fed by a water pipe that has a solenoid valve and a
small orifice to meter the water flow.
Post by dpb
--- Hide quoted text -
- Show quoted text -- Hide quoted text -
- Show quoted text -- Hide quoted text -
- Show quoted text -
Hi Trad...
nice job...
But I have the same questions as Frank and dpd..
1)The outlet water temperatues are almost the same so you have to
agree that when the water temp is the same the evap rate is the same.
So for at least part of the panal, the water temp and evap rates are
about the same.   In order for the overall evap rates to change by 2x,
there has to be a large portion of water panel with a large temp
diff.
Yes, I agree.
Post by m***@yahoo.com
2) I agree with the other poster, you assumed that the inflow is 73
and equal in all 3 cases.  It seems logical but even if there is a
small change in the inflow rate, it will make a big error in the
results.  I could imagine that hot water might not flow through an
orfice the same as cold, but I don't really know.
I thought about that a bit more after replying to dpb too. The
orifice is plastic, so it is possible that at a higher temp the
plastic could expand and constrict the opening.
Post by m***@yahoo.com
3) I am surprised that the flow through rate is so high.  For every 1
galllon that is evaporated about 5 to 10 gallons go down the drain.  I
was expecting the flow through rate to be more like 2 gallons in , 1
gallon out and 1 gallon evap.  The longer the water is in the
humidifer, then the less difference the inlet temp would make....  If
the water flows quickly right through then I can see why hot inlet
water might be more significant, but then the outlet temps would not
be the same so I don't know...??????
That's a good point. The higher the flow rate, the greater the
distance down the media element the hot water will be present. And
conversely, with cold water the longer cold water will be present.
But the flow rate must be such that with evaporation it reaches the
steady-sate temp of 78F somewhere before the end of the media. And
from the other aspects we discussed, it must be fairly far down the
media.

I'm now curious as to why they have the flow rate so high. You need
a reasonable flow rate to keep the minerals from building up, but I
agree that it seems a lot higher than you would expect. Something
around 50-50, as you suggest seems like it would be sufficient.
Curiously, Aprilaire says not to try to reduce the water flow using a
valve. But, I have to say, it seems like energy is being wasted
heating all this water, either in the furnace or the water heater. I
think I may reduce the flow in mine to see what happens, how fast the
minerals accumulate, etc.
Post by m***@yahoo.com
4) Whats the air temp from the furnace that is flowing by the water?
Don;'t know, didn't measure that.
Post by m***@yahoo.com
If you verify that the inlet water rates are really 73 in all three
cases,  I will be willing to concede...
If I had thought about it at the time, I certainly would have measured
it. It would have been easy to do. I agree that it's an
interesting possibility and the only remaining possible variable.
So, to eliminate that, I will test the flow rate at hot and cold.
Post by m***@yahoo.com
(and I thank everyone for keeping this discussion civil)
Mark- Hide quoted text -
- Show quoted text -
Bubba
2009-02-12 15:29:46 UTC
Permalink
Raw Message
Post by t***@optonline.net
Post by m***@yahoo.com
Post by t***@optonline.net
Post by dpb
...
Post by t***@optonline.net
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp     Water collected in 5 mins    Temp of Water Exiting Drain Hose
 51F        66.5 Oz                                  78.4F
102         61.5                                     78.0
135         58.0                                     79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow:   73.0 Oz
 51F    73 - 66.5 =  6.5 Oz
102     73 - 61.5 = 11.5
135     73 - 58.0 = 15.0
Using hot water more than doubled the output.  Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water.     Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
...
Hmmm....along w/ Frank I'm puzzled by the apparent paradox in the
thermodynamics here.
My first question would have to do w/ whether the assumption of constant
input flow rate is valid not knowing the Aprilaire at all.  Secondly the
exit temperatures seem puzzling.
The flow rate is determined by the water pressure and by an orifice
with a small hole at the solenoid valve.   It's hard to imagine that
hot water would flow at a slower rate through it, which is what would
be needed to skew the results.
What's puzzling about the exit temps?   They are for practical
purposes all the same.  Which is what one would expect.  If you start
with cold water, then the water temp rises on it's way down the
panel.  If it's hot water, it cools on it's way down.  Either way,
with a lot of air blowing on the panel, it seems reasonable that it
reaches a final temp somewhere before the end of the panel.
The only thing that is a little surprising to me is the amount of
difference hot vs cold made.  I would have thought that there could be
a 25 to 50% difference.  I think it has to do with the fact that
evaporation in this case is a complex process, not entirely described
by latent heat.   All you have to do is have the air moving by catch
some of the higher energy particles that are trying to escape the
surface tension of the water.
Post by dpb
Would take knowing and/or learning far more about the specifics of the
Aprilaire and the installation and the experiment than I care to
quantify the results, however... :)
It's essentially a panel with max surface area, through which air
flows.   It's fed by a water pipe that has a solenoid valve and a
small orifice to meter the water flow.
Post by dpb
--- Hide quoted text -
- Show quoted text -- Hide quoted text -
- Show quoted text -- Hide quoted text -
- Show quoted text -
Hi Trad...
nice job...
But I have the same questions as Frank and dpd..
1)The outlet water temperatues are almost the same so you have to
agree that when the water temp is the same the evap rate is the same.
So for at least part of the panal, the water temp and evap rates are
about the same.   In order for the overall evap rates to change by 2x,
there has to be a large portion of water panel with a large temp
diff.
Yes, I agree.
Post by m***@yahoo.com
2) I agree with the other poster, you assumed that the inflow is 73
and equal in all 3 cases.  It seems logical but even if there is a
small change in the inflow rate, it will make a big error in the
results.  I could imagine that hot water might not flow through an
orfice the same as cold, but I don't really know.
I thought about that a bit more after replying to dpb too. The
orifice is plastic, so it is possible that at a higher temp the
plastic could expand and constrict the opening.
Post by m***@yahoo.com
3) I am surprised that the flow through rate is so high.  For every 1
galllon that is evaporated about 5 to 10 gallons go down the drain.  I
was expecting the flow through rate to be more like 2 gallons in , 1
gallon out and 1 gallon evap.  The longer the water is in the
humidifer, then the less difference the inlet temp would make....  If
the water flows quickly right through then I can see why hot inlet
water might be more significant, but then the outlet temps would not
be the same so I don't know...??????
That's a good point. The higher the flow rate, the greater the
distance down the media element the hot water will be present. And
conversely, with cold water the longer cold water will be present.
But the flow rate must be such that with evaporation it reaches the
steady-sate temp of 78F somewhere before the end of the media. And
from the other aspects we discussed, it must be fairly far down the
media.
I'm now curious as to why they have the flow rate so high. You need
a reasonable flow rate to keep the minerals from building up, but I
agree that it seems a lot higher than you would expect. Something
around 50-50, as you suggest seems like it would be sufficient.
Curiously, Aprilaire says not to try to reduce the water flow using a
valve. But, I have to say, it seems like energy is being wasted
heating all this water, either in the furnace or the water heater.
Excuse me. Did trader just say that? The Aprilaire is wasting water
and energy? Could it be? And you had to do that experiment that you
screwed up to come up with that conclusion? Wow.
Most intelligent people could simply look at the drain tube while the
unit is running to figure that out.
Im beginning to think you are hopeless trader.
Post by t***@optonline.net
I think I may reduce the flow in mine to see what happens, how fast the
minerals accumulate, etc.
Post by m***@yahoo.com
4) Whats the air temp from the furnace that is flowing by the water?
Don;'t know, didn't measure that.
Post by m***@yahoo.com
If you verify that the inlet water rates are really 73 in all three
cases,  I will be willing to concede...
If I had thought about it at the time, I certainly would have measured
it. It would have been easy to do. I agree that it's an
interesting possibility and the only remaining possible variable.
So, to eliminate that, I will test the flow rate at hot and cold.
Keee_Rhist! How many more months will it take you to accomplish that
little test?
Bubba
Post by t***@optonline.net
Post by m***@yahoo.com
(and I thank everyone for keeping this discussion civil)
Mark- Hide quoted text -
- Show quoted text -
dpb
2009-02-12 15:50:12 UTC
Permalink
Raw Message
***@optonline.net wrote:
...
Post by t***@optonline.net
Post by m***@yahoo.com
2) I agree with the other poster, you assumed that the inflow is 73
and equal in all 3 cases. It seems logical but even if there is a
small change in the inflow rate, it will make a big error in the
results. I could imagine that hot water might not flow through an
orfice the same as cold, but I don't really know.
I thought about that a bit more after replying to dpb too. The
orifice is plastic, so it is possible that at a higher temp the
plastic could expand and constrict the opening.
I'd be more suspect of some pressure differential changes -- a slight
pressure change w/ the temperature, for example could make a significant
difference.

...
Post by t***@optonline.net
I'm now curious as to why they have the flow rate so high. You need
a reasonable flow rate to keep the minerals from building up, but I
agree that it seems a lot higher than you would expect. Something
around 50-50, as you suggest seems like it would be sufficient.
Curiously, Aprilaire says not to try to reduce the water flow using a
valve. But, I have to say, it seems like energy is being wasted
heating all this water, either in the furnace or the water heater. I
think I may reduce the flow in mine to see what happens, how fast the
minerals accumulate, etc.
...

It certainly is an energy hog and a waste of water as well.

It would seem to me the only logical installation would be to both put a
reducing valve in the line and to recirculate the waste back into the
system rather than pouring it down the drain.
Post by t***@optonline.net
If I had thought about it at the time, I certainly would have measured
it. It would have been easy to do. I agree that it's an
interesting possibility and the only remaining possible variable.
...

I'd certainly not go any place close to so far as to say it's "the only
remaining possible" variable.

To evaluate more fully would take a looking at the specific setup and
all in depth which obviously isn't possible over usenet. I say this not
as an attack but as a point of emphasis based on 20+ years of
involvement in industrial experimental design and testing wherein one
soon learns real humility in discovering how easily one can overlook
unexpected effects or hidden correlated variables that confound test
results even in the (apparently) simplest of conditions.

I'm willing to admit the nonlinear effect and direction is probably real
owing to the vapor pressure effect noted earlier; I'm far from agreeing
the quantitative values are more precise than simply estimates at this
point.

In regard to this last point I'll add the point that I intended to make
in the previous posting that in all likelihood it isn't all actually
evaporation but a significant amount is likely simply atomization and
mass transfer added by the higher temperature raising the water vapor
pressure.

--
dpb
2009-02-13 01:19:42 UTC
Permalink
Raw Message
dpb wrote:
...
Post by dpb
In regard to this last point I'll add the point that I intended to make
in the previous posting that in all likelihood it isn't all actually
evaporation but a significant amount is likely simply atomization and
mass transfer added by the higher temperature raising the water vapor
pressure.
Typo is confusing in the last sentence..."added" was intended as "aided"

--
Bubba
2009-02-12 00:49:27 UTC
Permalink
Raw Message
Post by t***@optonline.net
For those of you that followed any of the discussions here about
whether using hot water versus cold water in a furnace humidifier
makes a difference in the amount of water that evaporates, I did the
actual test on my unit. Here's exactly how I did it and the results.
The unit is an Aprilaire 700A installed on a gas forced air furnace.
To do the test, I made sure to keep everything constant except the
incoming water temp. My unit is connected to hot water, so to change
the water temp, I turned off the water heater and used up the hot
water through normal household use. I got the hot water tank temp
down to 51F. The house humidity was 37% at the time of the test and
the temp was 67F. I routed the humdifier drain hose to a location
that I could put a gallon container under it and remove it without
disturbing the hose. I placed a temporary container under the running
hose to catch the water. I then started the furnace with the
humidifier set high enough to be running constantly. I let the
system stabilize for 5 mins to get to a steady-state. Then I quickly
replaced the temporary container with another empty gallon container
and started a stop watch. During the 5 min period, I also measured
the temp of the water exiting the drain hose. At precisely 5 mins, I
removed the container and used a measuring cup to determine the volume
of water. I also shut down the furnace.
Then, I fired the water heater back up and let it run to get the water
temp to a higher temp to see what happens with medium temp warm
water. I then turned the water heater off again. That temp turned
out to be 102F. I then repeated the process of starting the furnace,
letting it run for 5 mins to stabilize, then measuring the drain water
output for another 5 minutes. Next, I fired the water heater up
again and allowed it to come up to normal temperture. And again, I
turned on the furnace, let it stabilize for 5 mins, then measured the
water output for 5 mins.
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp Water collected in 5 mins Temp of Water Exiting Drain Hose
51F 66.5 Oz 78.4F
102 61.5 78.0
135 58.0 79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow: 73.0 Oz
51F 73 - 66.5 = 6.5 Oz
102 73 - 61.5 = 11.5
135 73 - 58.0 = 15.0
Using hot water more than doubled the output. Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water. Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
So, there you have it folks. This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
Well trader, of course you knew I would respond but I will try to be
civil. I am rather suspicious that after all this time you have "ALL
OF A SUDDEN" performed the test out of the blue and come up with your
results. You've been so against doing the test and now all of a sudden
had a change of heart? I wouldnt be half suprised if you made up all
these numbers BUT, I will give you the benefit of the doubt that you
did it. My suggestion would be to DO IT OVER and figured out where you
screwed up.
77% and 131% more output??? What, are you magic too. Can you wiggle
your nose and produce a rabbit out of a hat? You've "hosed" something
with your test. Very minimal improvement (output) would have been
expected.
Try Again.
Bubba
t***@optonline.net
2009-02-12 13:58:22 UTC
Permalink
Raw Message
Post by Bubba
Post by t***@optonline.net
For those of you that followed any of the discussions here about
whether using hot water versus cold water in a furnace humidifier
makes a difference in the amount of water that evaporates, I did the
actual test on my unit.  Here's exactly how I did it and the results.
The unit is an Aprilaire 700A installed on a gas forced air furnace.
To do the test, I made sure to keep everything constant except the
incoming water temp.  My unit is connected to hot water, so to change
the water temp, I turned off the water heater and used up the hot
water through normal household use.  I got the hot water tank temp
down to 51F.  The house humidity was 37% at the time of the test and
the temp was 67F.   I routed the humdifier drain hose to a location
that I could put a gallon container under it and remove it without
disturbing the hose. I placed a temporary container under the running
hose to catch the water.    I then started the furnace with the
humidifier set high enough to be running constantly.    I let the
system stabilize for 5 mins to get to a steady-state.   Then I quickly
replaced the temporary container with another empty gallon container
and started a stop watch.  During the 5 min period, I also measured
the temp of the water exiting the drain hose.   At precisely 5 mins, I
removed the container and used a measuring cup to determine the volume
of water.   I also shut down the furnace.
Then, I fired the water heater back up and let it run to get the water
temp to a higher temp to see what happens with medium temp warm
water.  I then turned the water heater off again.   That temp turned
out to be 102F.   I then repeated the process of starting the furnace,
letting it run for 5 mins to stabilize, then measuring the drain water
output for another 5 minutes.     Next, I fired the water heater up
again and allowed it to come up to normal temperture.   And again, I
turned on the furnace, let it stabilize for 5 mins, then measured the
water output for 5 mins.
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp     Water collected in 5 mins    Temp of Water Exiting Drain Hose
51F         66.5 Oz                                  78.4F
102         61.5                                       78.0
135         58.0                                       79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow:   73.0 Oz
51F     73 - 66.5 =  6.5 Oz
102     73 - 61.5 = 11.5
135     73 - 58.0 = 15.0
Using hot water more than doubled the output.  Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water.     Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
So, there you have it folks.  This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
Well trader, of course you knew I would respond but I will try to be
civil. I am rather suspicious that after all this time you have "ALL
OF A SUDDEN" performed the test out of the blue and  come up with your
results. You've been so against doing the test and now all of a sudden
had a change of heart?
You know perfectly well that's not true. I never once said I was
against doing the test. I said several times that I would do the
test when I had the opportunity.
Post by Bubba
I wouldnt be half suprised if you made up all
these numbers BUT, I will give you the benefit of the doubt that you
did it. My suggestion would be to DO IT OVER and figured out where you
screwed up.
77% and 131% more output??? What, are you magic too. Can you wiggle
your nose and produce a rabbit out of a hat? You've "hosed" something
with your test. Very minimal improvement (output) would have been
expected.
Try Again.
Bubba- Hide quoted text -
And just as I predicted many posts ago, you now dismiss the results of
the test. Since you want to claim I hosed up something, let me point
out a few facts. In another thread, when you wanted to know why I
hadn't yet done the test, you stated that it would only take 5 or 10
minutes to perform. Clearly, you can't perform this test in that
period of time. I let the furnace run each time for 5 mins just to
let it reach a steady-state condition. Apparently that concept and
I'm sure a lot more escaped you. That you stated this test could be
done in 5 or 10 minutes, combined with your previous rants against
engineering and science, should give everyone here a good indication
of who actually took the time required, knew how to design the
experiment and did a valid test.

It's clear that the amount of water evaporated compared to what comes
out the drain is small, only 10 or 20%. So, if you just stared into
a big old 5 gallon pail for 5 mins, you would never notice any
difference and coclude that it doesn't matter. Only by taking the
time, keeping everything constant, and taking careful measurements
would you find out the difference.
Bubba
2009-02-12 15:25:20 UTC
Permalink
Raw Message
Post by t***@optonline.net
Post by Bubba
Post by t***@optonline.net
For those of you that followed any of the discussions here about
whether using hot water versus cold water in a furnace humidifier
makes a difference in the amount of water that evaporates, I did the
actual test on my unit.  Here's exactly how I did it and the results.
The unit is an Aprilaire 700A installed on a gas forced air furnace.
To do the test, I made sure to keep everything constant except the
incoming water temp.  My unit is connected to hot water, so to change
the water temp, I turned off the water heater and used up the hot
water through normal household use.  I got the hot water tank temp
down to 51F.  The house humidity was 37% at the time of the test and
the temp was 67F.   I routed the humdifier drain hose to a location
that I could put a gallon container under it and remove it without
disturbing the hose. I placed a temporary container under the running
hose to catch the water.    I then started the furnace with the
humidifier set high enough to be running constantly.    I let the
system stabilize for 5 mins to get to a steady-state.   Then I quickly
replaced the temporary container with another empty gallon container
and started a stop watch.  During the 5 min period, I also measured
the temp of the water exiting the drain hose.   At precisely 5 mins, I
removed the container and used a measuring cup to determine the volume
of water.   I also shut down the furnace.
Then, I fired the water heater back up and let it run to get the water
temp to a higher temp to see what happens with medium temp warm
water.  I then turned the water heater off again.   That temp turned
out to be 102F.   I then repeated the process of starting the furnace,
letting it run for 5 mins to stabilize, then measuring the drain water
output for another 5 minutes.     Next, I fired the water heater up
again and allowed it to come up to normal temperture.   And again, I
turned on the furnace, let it stabilize for 5 mins, then measured the
water output for 5 mins.
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp     Water collected in 5 mins    Temp of Water Exiting Drain Hose
51F         66.5 Oz                                  78.4F
102         61.5                                       78.0
135         58.0                                       79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow:   73.0 Oz
51F     73 - 66.5 =  6.5 Oz
102     73 - 61.5 = 11.5
135     73 - 58.0 = 15.0
Using hot water more than doubled the output.  Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water.     Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
So, there you have it folks.  This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
Well trader, of course you knew I would respond but I will try to be
civil. I am rather suspicious that after all this time you have "ALL
OF A SUDDEN" performed the test out of the blue and  come up with your
results. You've been so against doing the test and now all of a sudden
had a change of heart?
You know perfectly well that's not true. I never once said I was
against doing the test. I said several times that I would do the
test when I had the opportunity.
Would you like me to go way back a couple of months to where this
first started and point out how long it took you to do this simple
test that you have obviously screwed up?
Post by t***@optonline.net
Post by Bubba
I wouldnt be half suprised if you made up all
these numbers BUT, I will give you the benefit of the doubt that you
did it. My suggestion would be to DO IT OVER and figured out where you
screwed up.
77% and 131% more output??? What, are you magic too. Can you wiggle
your nose and produce a rabbit out of a hat? You've "hosed" something
with your test. Very minimal improvement (output) would have been
expected.
Try Again.
Bubba- Hide quoted text -
And just as I predicted many posts ago, you now dismiss the results of
the test.
Of course I am. Did you bother to take time out and look at the
numbers you actually wrote down? 131% more output using hot water??
Dont you think if Aprilaire was able to acheive that, they would have
that plastered all over their literature?
"Aprilaire, the magical humidifier. It manufacturers its own humidity"
Post by t***@optonline.net
Since you want to claim I hosed up something, let me point
out a few facts. In another thread, when you wanted to know why I
hadn't yet done the test, you stated that it would only take 5 or 10
minutes to perform. Clearly, you can't perform this test in that
period of time.
OK, big friggin deal. A half hour. You feel better now? I cant help it
if it took you all day to do something simple. Typical EE. Drag it out
for hours, drink some coffee, think, ponder, think some more, go take
a walk, read a novel, scratch your ass, etc.
Post by t***@optonline.net
let the furnace run each time for 5 mins just to
let it reach a steady-state condition. Apparently that concept and
I'm sure a lot more escaped you. That you stated this test could be
done in 5 or 10 minutes, combined with your previous rants against
engineering and science, should give everyone here a good indication
of who actually took the time required, knew how to design the
experiment and did a valid test.
No, I think it proves that even someone with the supposed training of
even an EE degree can screw up a purely simple experiment to the point
that he thinks he just invented the wheel.
Post by t***@optonline.net
It's clear that the amount of water evaporated compared to what comes
out the drain is small, only 10 or 20%. So, if you just stared into
a big old 5 gallon pail for 5 mins, you would never notice any
difference and coclude that it doesn't matter. Only by taking the
time, keeping everything constant, and taking careful measurements
would you find out the difference.
and clearly, you even screw that task up.
Bubba
glenn36
2011-02-20 16:04:00 UTC
Permalink
Raw Message
responding to
http://www.homeownershub.com/maintenance/Humidifier-Hot-vs-Cold-Water-Experiment-358875-.htm
glenn36 wrote:

***@optonline.net wrote:

where is the locatin of the humdifier return or supply
Post by t***@optonline.net
For those of you that followed any of the discussions here about
whether using hot water versus cold water in a furnace humidifier
makes a difference in the amount of water that evaporates, I did the
actual test on my unit. Here\\\'s exactly how I did it and the results.
The unit is an Aprilaire 700A installed on a gas forced air furnace.
To do the test, I made sure to keep everything constant except the
incoming water temp. My unit is connected to hot water, so to change
the water temp, I turned off the water heater and used up the hot
water through normal household use. I got the hot water tank temp
down to 51F. The house humidity was 37% at the time of the test and
the temp was 67F. I routed the humdifier drain hose to a location
that I could put a gallon container under it and remove it without
disturbing the hose. I placed a temporary container under the running
hose to catch the water. I then started the furnace with the
humidifier set high enough to be running constantly. I let the
system stabilize for 5 mins to get to a steady-state. Then I quickly
replaced the temporary container with another empty gallon container
and started a stop watch. During the 5 min period, I also measured
the temp of the water exiting the drain hose. At precisely 5 mins, I
removed the container and used a measuring cup to determine the volume
of water. I also shut down the furnace.
Then, I fired the water heater back up and let it run to get the water
temp to a higher temp to see what happens with medium temp warm
water. I then turned the water heater off again. That temp turned
out to be 102F. I then repeated the process of starting the furnace,
letting it run for 5 mins to stabilize, then measuring the drain water
output for another 5 minutes. Next, I fired the water heater up
again and allowed it to come up to normal temperture. And again, I
turned on the furnace, let it stabilize for 5 mins, then measured the
water output for 5 mins.
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp Water collected in 5 mins Temp of Water Exiting Drain Hose
51F 66.5 Oz 78.4F
102 61.5 78.0
135 58.0 79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow: 73.0 Oz
51F 73 - 66.5 = 6.5 Oz
102 73 - 61.5 = 11.5
135 73 - 58.0 = 15.0
Using hot water more than doubled the output. Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water. Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
So, there you have it folks. This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
-------------------------------------
l***@gmail.com
2017-01-05 15:58:07 UTC
Permalink
Raw Message
Post by t***@optonline.net
For those of you that followed any of the discussions here about
whether using hot water versus cold water in a furnace humidifier
makes a difference in the amount of water that evaporates, I did the
actual test on my unit. Here's exactly how I did it and the results.
The unit is an Aprilaire 700A installed on a gas forced air furnace.
To do the test, I made sure to keep everything constant except the
incoming water temp. My unit is connected to hot water, so to change
the water temp, I turned off the water heater and used up the hot
water through normal household use. I got the hot water tank temp
down to 51F. The house humidity was 37% at the time of the test and
the temp was 67F. I routed the humdifier drain hose to a location
that I could put a gallon container under it and remove it without
disturbing the hose. I placed a temporary container under the running
hose to catch the water. I then started the furnace with the
humidifier set high enough to be running constantly. I let the
system stabilize for 5 mins to get to a steady-state. Then I quickly
replaced the temporary container with another empty gallon container
and started a stop watch. During the 5 min period, I also measured
the temp of the water exiting the drain hose. At precisely 5 mins, I
removed the container and used a measuring cup to determine the volume
of water. I also shut down the furnace.
Then, I fired the water heater back up and let it run to get the water
temp to a higher temp to see what happens with medium temp warm
water. I then turned the water heater off again. That temp turned
out to be 102F. I then repeated the process of starting the furnace,
letting it run for 5 mins to stabilize, then measuring the drain water
output for another 5 minutes. Next, I fired the water heater up
again and allowed it to come up to normal temperture. And again, I
turned on the furnace, let it stabilize for 5 mins, then measured the
water output for 5 mins.
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp Water collected in 5 mins Temp of Water Exiting Drain Hose
51F 66.5 Oz 78.4F
102 61.5 78.0
135 58.0 79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow: 73.0 Oz
51F 73 - 66.5 = 6.5 Oz
102 73 - 61.5 = 11.5
135 73 - 58.0 = 15.0
Using hot water more than doubled the output. Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water. Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
So, there you have it folks. This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
Thats a great result. I fully expected to get much higher output from the humidifier with hotter water. What surprised me is that the drain temperature wasn't much hotter. To me this says that you aren't really "wasting" the energy by using hot water. You aren't putting more BTU's down the drain.

I'm putting an Aprilaire 700M in my house over the weekend. This convinced me to go ahead and use hot water. I run an ecobee thermostat that is set up to periodically run the blower to keep house air mixed even if no heat is needed. I was worried about how to make this work with the humidifier but now I'll just tie in to the hot water and use a current sensing relay tied to the blower.
trader_4
2017-01-05 16:30:40 UTC
Permalink
Raw Message
Post by l***@gmail.com
Post by t***@optonline.net
For those of you that followed any of the discussions here about
whether using hot water versus cold water in a furnace humidifier
makes a difference in the amount of water that evaporates, I did the
actual test on my unit. Here's exactly how I did it and the results.
The unit is an Aprilaire 700A installed on a gas forced air furnace.
To do the test, I made sure to keep everything constant except the
incoming water temp. My unit is connected to hot water, so to change
the water temp, I turned off the water heater and used up the hot
water through normal household use. I got the hot water tank temp
down to 51F. The house humidity was 37% at the time of the test and
the temp was 67F. I routed the humdifier drain hose to a location
that I could put a gallon container under it and remove it without
disturbing the hose. I placed a temporary container under the running
hose to catch the water. I then started the furnace with the
humidifier set high enough to be running constantly. I let the
system stabilize for 5 mins to get to a steady-state. Then I quickly
replaced the temporary container with another empty gallon container
and started a stop watch. During the 5 min period, I also measured
the temp of the water exiting the drain hose. At precisely 5 mins, I
removed the container and used a measuring cup to determine the volume
of water. I also shut down the furnace.
Then, I fired the water heater back up and let it run to get the water
temp to a higher temp to see what happens with medium temp warm
water. I then turned the water heater off again. That temp turned
out to be 102F. I then repeated the process of starting the furnace,
letting it run for 5 mins to stabilize, then measuring the drain water
output for another 5 minutes. Next, I fired the water heater up
again and allowed it to come up to normal temperture. And again, I
turned on the furnace, let it stabilize for 5 mins, then measured the
water output for 5 mins.
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp Water collected in 5 mins Temp of Water Exiting Drain Hose
51F 66.5 Oz 78.4F
102 61.5 78.0
135 58.0 79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow: 73.0 Oz
51F 73 - 66.5 = 6.5 Oz
102 73 - 61.5 = 11.5
135 73 - 58.0 = 15.0
Using hot water more than doubled the output. Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water. Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
So, there you have it folks. This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
Thats a great result. I fully expected to get much higher output from the humidifier with hotter water. What surprised me is that the drain temperature wasn't much hotter. To me this says that you aren't really "wasting" the energy by using hot water. You aren't putting more BTU's down the drain.
I'm putting an Aprilaire 700M in my house over the weekend. This convinced me to go ahead and use hot water. I run an ecobee thermostat that is set up to periodically run the blower to keep house air mixed even if no heat is needed. I was worried about how to make this work with the humidifier but now I'll just tie in to the hot water and use a current sensing relay tied to the blower.
Well, usually when someone replies to a six year old post, people
here jump on them, saying things like "that guy died 5 years ago
from too little humidity". But here I am, still here.

If it were me, I'd probably rig it up to run when the burner is on.
That's what I did with mine. At the very least you're going to
use more water running it without heat. And while you get much of
the heat from the hot water into the house, if the incoming cold
water is 40F, you're not going to get whatever heat it takes for
the WH to raise it up from 40F to around room temp, so the more
water it uses, the more energy is wasted. Running with heat on
will minimize the water and energy usage. How much of a difference
it makes in the grand scheme, IDK.
FromTheRafters
2017-01-05 16:57:54 UTC
Permalink
Raw Message
Post by trader_4
Post by l***@gmail.com
Post by t***@optonline.net
For those of you that followed any of the discussions here about
whether using hot water versus cold water in a furnace humidifier
makes a difference in the amount of water that evaporates, I did the
actual test on my unit. Here's exactly how I did it and the results.
The unit is an Aprilaire 700A installed on a gas forced air furnace.
To do the test, I made sure to keep everything constant except the
incoming water temp. My unit is connected to hot water, so to change
the water temp, I turned off the water heater and used up the hot
water through normal household use. I got the hot water tank temp
down to 51F. The house humidity was 37% at the time of the test and
the temp was 67F. I routed the humdifier drain hose to a location
that I could put a gallon container under it and remove it without
disturbing the hose. I placed a temporary container under the running
hose to catch the water. I then started the furnace with the
humidifier set high enough to be running constantly. I let the
system stabilize for 5 mins to get to a steady-state. Then I quickly
replaced the temporary container with another empty gallon container
and started a stop watch. During the 5 min period, I also measured
the temp of the water exiting the drain hose. At precisely 5 mins, I
removed the container and used a measuring cup to determine the volume
of water. I also shut down the furnace.
Then, I fired the water heater back up and let it run to get the water
temp to a higher temp to see what happens with medium temp warm
water. I then turned the water heater off again. That temp turned
out to be 102F. I then repeated the process of starting the furnace,
letting it run for 5 mins to stabilize, then measuring the drain water
output for another 5 minutes. Next, I fired the water heater up
again and allowed it to come up to normal temperture. And again, I
turned on the furnace, let it stabilize for 5 mins, then measured the
water output for 5 mins.
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp Water collected in 5 mins Temp of Water Exiting Drain Hose
51F 66.5 Oz 78.4F
102 61.5 78.0
135 58.0 79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow: 73.0 Oz
51F 73 - 66.5 = 6.5 Oz
102 73 - 61.5 = 11.5
135 73 - 58.0 = 15.0
Using hot water more than doubled the output. Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water. Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
So, there you have it folks. This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
Thats a great result. I fully expected to get much higher output from the
humidifier with hotter water. What surprised me is that the drain
temperature wasn't much hotter. To me this says that you aren't really
"wasting" the energy by using hot water. You aren't putting more BTU's down
the drain.
I'm putting an Aprilaire 700M in my house over the weekend. This convinced
me to go ahead and use hot water. I run an ecobee thermostat that is set up
to periodically run the blower to keep house air mixed even if no heat is
needed. I was worried about how to make this work with the humidifier but
now I'll just tie in to the hot water and use a current sensing relay tied
to the blower.
Well, usually when someone replies to a six year old post, people
here jump on them, saying things like "that guy died 5 years ago
from too little humidity". But here I am, still here.
You're safe probably because you don't have gerbils. There seems to be
a strong correlation between death and gerbil ownership.
Post by trader_4
If it were me, I'd probably rig it up to run when the burner is on.
That's what I did with mine. At the very least you're going to
use more water running it without heat. And while you get much of
the heat from the hot water into the house, if the incoming cold
water is 40F, you're not going to get whatever heat it takes for
the WH to raise it up from 40F to around room temp, so the more
water it uses, the more energy is wasted. Running with heat on
will minimize the water and energy usage. How much of a difference
it makes in the grand scheme, IDK.
Interesting and well thought out experiment IMO. It seems to be a good
guess according to theory, but it's nice to get actual data as opposed
to guesses.
m***@yahoo.com
2017-01-05 18:31:25 UTC
Permalink
Raw Message
Post by trader_4
If it were me, I'd probably rig it up to run when the burner is on.
That's what I did with mine. At the very least you're going to
use more water running it without heat. And while you get much of
the heat from the hot water into the house, if the incoming cold
water is 40F, you're not going to get whatever heat it takes for
the WH to raise it up from 40F to around room temp, so the more
water it uses, the more energy is wasted.
I wouldn't call it "wasted".

It takes energy to evaporate water no matter what.

If you want to add X gallons of moisture to the air, it's gonna take Y BTUs of energy no matter what.

The only issue is where those BTUs come from and how much they cost.

If you are using a gas water heater and gas furnace, there is not really any difference.

m
trader_4
2017-01-06 15:55:03 UTC
Permalink
Raw Message
Post by m***@yahoo.com
Post by trader_4
If it were me, I'd probably rig it up to run when the burner is on.
That's what I did with mine. At the very least you're going to
use more water running it without heat. And while you get much of
the heat from the hot water into the house, if the incoming cold
water is 40F, you're not going to get whatever heat it takes for
the WH to raise it up from 40F to around room temp, so the more
water it uses, the more energy is wasted.
I wouldn't call it "wasted".
It takes energy to evaporate water no matter what.
If you want to add X gallons of moisture to the air, it's gonna take Y BTUs of energy no matter what.
Consider two methods of adding 1 gallon of water to the air:

1 - Draw 1 gal of 130F hot water and place it in the furnace, leave
it there with the furnace running until it's all evaporated.

2 - Draw 1 cup of 130F hot water, place it in the furnace, and at
the same time draw a cup of 80F water and pour it down the drain.
This is similar to what happens with his humidifier.

If the incoming water is 40F, you're wasting the energy used to
raise the water from 40F to 80F, its going down the drain.
Post by m***@yahoo.com
The only issue is where those BTUs come from and how much they cost.
If you are using a gas water heater and gas furnace, there is not really any difference.
m
In general, I agree with you, and that was my key point from my post
years ago. The key is that assumes the run time of the humdifier
is about the same. He is proposing to let the humidifier run whenever
the blower is on, including when there is no heat. Doing that, the
humidifier will be running part of the time with no furnace heat.
That means it will take much longer to put X amount of water in the
air and while it's running, you have water that's comining into the
WH at ~40F going down the drain at ~70F, which is additonal energy
that's wasted.

In the grand scheme of things, ID?K how much diff it makes, but the
effect is there.
m***@yahoo.com
2017-01-06 22:23:13 UTC
Permalink
Raw Message
Post by trader_4
Post by m***@yahoo.com
Post by trader_4
If it were me, I'd probably rig it up to run when the burner is on.
That's what I did with mine. At the very least you're going to
use more water running it without heat. And while you get much of
the heat from the hot water into the house, if the incoming cold
water is 40F, you're not going to get whatever heat it takes for
the WH to raise it up from 40F to around room temp, so the more
water it uses, the more energy is wasted.
I wouldn't call it "wasted".
It takes energy to evaporate water no matter what.
If you want to add X gallons of moisture to the air, it's gonna take Y BTUs of energy no matter what.
1 - Draw 1 gal of 130F hot water and place it in the furnace, leave
it there with the furnace running until it's all evaporated.
2 - Draw 1 cup of 130F hot water, place it in the furnace, and at
the same time draw a cup of 80F water and pour it down the drain.
This is similar to what happens with his humidifier.
If the incoming water is 40F, you're wasting the energy used to
raise the water from 40F to 80F, its going down the drain.
Post by m***@yahoo.com
The only issue is where those BTUs come from and how much they cost.
If you are using a gas water heater and gas furnace, there is not really any difference.
m
In general, I agree with you, and that was my key point from my post
years ago. The key is that assumes the run time of the humdifier
is about the same. He is proposing to let the humidifier run whenever
the blower is on, including when there is no heat. Doing that, the
humidifier will be running part of the time with no furnace heat.
That means it will take much longer to put X amount of water in the
air and while it's running, you have water that's comining into the
WH at ~40F going down the drain at ~70F, which is additonal energy
that's wasted.
In the grand scheme of things, ID?K how much diff it makes, but the
effect is there.
the humdifier will USE more energy because of the longer run time of the humidifier

but I would not say it is wasted because he will also get more
moisture in return for that energy.

m
trader_4
2017-01-07 20:54:31 UTC
Permalink
Raw Message
Post by m***@yahoo.com
Post by trader_4
Post by m***@yahoo.com
Post by trader_4
If it were me, I'd probably rig it up to run when the burner is on.
That's what I did with mine. At the very least you're going to
use more water running it without heat. And while you get much of
the heat from the hot water into the house, if the incoming cold
water is 40F, you're not going to get whatever heat it takes for
the WH to raise it up from 40F to around room temp, so the more
water it uses, the more energy is wasted.
I wouldn't call it "wasted".
It takes energy to evaporate water no matter what.
If you want to add X gallons of moisture to the air, it's gonna take Y BTUs of energy no matter what.
1 - Draw 1 gal of 130F hot water and place it in the furnace, leave
it there with the furnace running until it's all evaporated.
2 - Draw 1 cup of 130F hot water, place it in the furnace, and at
the same time draw a cup of 80F water and pour it down the drain.
This is similar to what happens with his humidifier.
If the incoming water is 40F, you're wasting the energy used to
raise the water from 40F to 80F, its going down the drain.
Post by m***@yahoo.com
The only issue is where those BTUs come from and how much they cost.
If you are using a gas water heater and gas furnace, there is not really any difference.
m
In general, I agree with you, and that was my key point from my post
years ago. The key is that assumes the run time of the humdifier
is about the same. He is proposing to let the humidifier run whenever
the blower is on, including when there is no heat. Doing that, the
humidifier will be running part of the time with no furnace heat.
That means it will take much longer to put X amount of water in the
air and while it's running, you have water that's comining into the
WH at ~40F going down the drain at ~70F, which is additonal energy
that's wasted.
In the grand scheme of things, ID?K how much diff it makes, but the
effect is there.
the humdifier will USE more energy because of the longer run time of the humidifier
but I would not say it is wasted because he will also get more
moisture in return for that energy.
m
It's wasted energy if the humidifier can keep the humidity of the house at the
desired level by just running when the heat is on, which everyone I've
ever seem will.
Uncle Monster
2017-01-06 07:51:10 UTC
Permalink
Raw Message
Post by trader_4
Post by l***@gmail.com
Post by t***@optonline.net
For those of you that followed any of the discussions here about
whether using hot water versus cold water in a furnace humidifier
makes a difference in the amount of water that evaporates, I did the
actual test on my unit. Here's exactly how I did it and the results.
The unit is an Aprilaire 700A installed on a gas forced air furnace.
To do the test, I made sure to keep everything constant except the
incoming water temp. My unit is connected to hot water, so to change
the water temp, I turned off the water heater and used up the hot
water through normal household use. I got the hot water tank temp
down to 51F. The house humidity was 37% at the time of the test and
the temp was 67F. I routed the humdifier drain hose to a location
that I could put a gallon container under it and remove it without
disturbing the hose. I placed a temporary container under the running
hose to catch the water. I then started the furnace with the
humidifier set high enough to be running constantly. I let the
system stabilize for 5 mins to get to a steady-state. Then I quickly
replaced the temporary container with another empty gallon container
and started a stop watch. During the 5 min period, I also measured
the temp of the water exiting the drain hose. At precisely 5 mins, I
removed the container and used a measuring cup to determine the volume
of water. I also shut down the furnace.
Then, I fired the water heater back up and let it run to get the water
temp to a higher temp to see what happens with medium temp warm
water. I then turned the water heater off again. That temp turned
out to be 102F. I then repeated the process of starting the furnace,
letting it run for 5 mins to stabilize, then measuring the drain water
output for another 5 minutes. Next, I fired the water heater up
again and allowed it to come up to normal temperture. And again, I
turned on the furnace, let it stabilize for 5 mins, then measured the
water output for 5 mins.
Finally, I measured the amount of incoming water into the humidifier
by connecting the drain hose directly to the water tube where it would
normally drop onto the distribution tray at the top of the panel.
Temp Water collected in 5 mins Temp of Water Exiting Drain Hose
51F 66.5 Oz 78.4F
102 61.5 78.0
135 58.0 79.2
Water collected during 5 mins direct from tube at top of humidifier,
ie incoming flow: 73.0 Oz
51F 73 - 66.5 = 6.5 Oz
102 73 - 61.5 = 11.5
135 73 - 58.0 = 15.0
Using hot water more than doubled the output. Or in percentage terms,
using 102F water resulted in 77% MORE water being evaporated compared
to 51F water. Using 135F water resulted in 131% MORE water being
evaporated compared to 51F water.
So, there you have it folks. This was IMO a very reasonable and
realistic mesurement and confirms why Aprilaire says you get higher
output with hot water.
Thats a great result. I fully expected to get much higher output from the humidifier with hotter water. What surprised me is that the drain temperature wasn't much hotter. To me this says that you aren't really "wasting" the energy by using hot water. You aren't putting more BTU's down the drain.
I'm putting an Aprilaire 700M in my house over the weekend. This convinced me to go ahead and use hot water. I run an ecobee thermostat that is set up to periodically run the blower to keep house air mixed even if no heat is needed. I was worried about how to make this work with the humidifier but now I'll just tie in to the hot water and use a current sensing relay tied to the blower.
Well, usually when someone replies to a six year old post, people
here jump on them, saying things like "that guy died 5 years ago
from too little humidity". But here I am, still here.
If it were me, I'd probably rig it up to run when the burner is on.
That's what I did with mine. At the very least you're going to
use more water running it without heat. And while you get much of
the heat from the hot water into the house, if the incoming cold
water is 40F, you're not going to get whatever heat it takes for
the WH to raise it up from 40F to around room temp, so the more
water it uses, the more energy is wasted. Running with heat on
will minimize the water and energy usage. How much of a difference
it makes in the grand scheme, IDK.
I believe your math is off a little. The OP is from 2009. You need a herd of gerbils. ヽ(ヅ)ノ

[8~{} Uncle Math Monster
SomeGuySomewhere
2017-01-15 19:14:02 UTC
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replying to trader4, SomeGuySomewhere wrote:
Were you able to raise the humidity level after switching to hit water then?

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