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.

On Wed, 11 Feb 2009 08:12:38 -0800 (PST), (E-Mail Removed) wrote:


-snip-
>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

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





"HeyBub" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) m...
> (E-Mail Removed) wrote:
>> 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.
>
> 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.
>

(E-Mail Removed) wrote:
> 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.
>
>
>
>
>
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.

(E-Mail Removed) wrote:
....

> 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.
....

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...

--

On Feb 11, 2:31*pm, dpb <n...@non.net> wrote:
> trad...@optonline.net wrote:
>
> ...
>
>
>
>
>
> > 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.
>
> ...
>
> 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.



>
> 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.




>
> --- Hide quoted text -
>
> - Show quoted text -

(E-Mail Removed) wrote:
> On Feb 11, 2:31 pm, dpb <n...@non.net> wrote:
....

>> 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.

> 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...

> 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...

--

On Feb 11, 3:05*pm, trad...@optonline.net wrote:
> On Feb 11, 2:31*pm, dpb <n...@non.net> wrote:
>
>
>
>
>
> > trad...@optonline.net wrote:
>
> > ...
>
> > > 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.
>
> > ...
>
> > 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.
>
>
>
> > 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.
>
>
>
>
>
> > --- 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

On Feb 11, 7:49*pm, Bubba <LiKeAlAkErem...@iname.com> wrote:
> On Wed, 11 Feb 2009 08:12:38 -0800 (PST), trad...@optonline.net wrote:
> >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.
>
> 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.



> 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.

On Feb 11, 5:34*pm, makol...@yahoo.com wrote:
> On Feb 11, 3:05*pm, trad...@optonline.net wrote:
>
>
>
>
>
> > On Feb 11, 2:31*pm, dpb <n...@non.net> wrote:
>
> > > trad...@optonline.net wrote:
>
> > > ...
>
> > > > 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 ExitingDrain 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.
>
> > > ...
>
> > > 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.
>
> > > 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.
>
> > > --- 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.



>
> 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.



>
> 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.



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

Don;'t know, didn't measure that.


>
> 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.




>
> (and I thank everyone for keeping this discussion civil)
>
> Mark- Hide quoted text -
>
> - Show quoted text -