# Humidifying with Geothermal

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• posted on February 10, 2009, 4:25 am

Bubba, I'm not sure what your question is...
I wasn't saying it's "worth it" to hook up the hot water... I agree with you, the heat of vaporization has to come from somehwere either way.., either all from the furnace or the 10% fom the hot water heater and 90% from the furnace...... so it's 6 of one half a dozen of another...
And if the hot water heater is electric and the furnace is something cheaper, then it's probably a looser to hook up the hot water.
Mark
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<%-name%>
• posted on February 10, 2009, 2:35 pm
On Feb 9, 11:25 pm, snipped-for-privacy@yahoo.com wrote:

Nor is anyone else.

But Bubba doesn't say that at all. He says the energy is a free ride if all comes from the furnace, since the furnace is running anyway. I agree with you Mark, that energy wise, it's close to a wash. Either the energy to heat the water comes partially from the water heater or all from the furnace. But either way, assuming the same fuel, the energy cost is close, because both have efficiencies in the same ballpark.

I would agree with that.
In fact, I think we agree on everything, except exactly how much more water evaporates in the humidifier using hot. You think it's not significant, but I and Aprilaire, think it is. I understand your point about how much heat is necessary to change the phase of water from liquid to vapor and how that heat is much larger than the heat to raise the water's temp. It's a very good point. However, my point is that evaporation using an air flow device like the humidifier is not as simple as just a phase change. It's a complex process involving mass transfer by the air too, which is a complex problem. To get those water molecules off the panel, all that has to happen is to have the fastest moving ones at the surface escape the surface tension of the water. The more energy those surface molecules have, the more likely they will be caught up and swept away by the fast moving air at the boundary layer..
Let me ask you this question. Let's say water enters the top of a rectangular distribution panel in the humidifier, which is about a foot long, and flows vertically down via gravity Let's say it's at 130 deg when it enters. Bubba claims the water has completely cooled before it's even reached the top of the distribution tray, which is to say it's cooled in just 1/2" inch while still in a pencil size stream. I'd say the temp drops more slowly, and the water temp could be higher using hot water for a good ways down the panel. Maybe 1/2 way down. So you have a temp gradient going down the panel from 130 to whatever the final stead-state temp is going to be, let's say for discussion that it's 90 deg.
In the case of using cold water, you have the opposite. Water is entering at 40 deg and going up to 90 deg for some portion of the panel. Eventually, it rises to the same steady state temp, of 90 deg. So, in once case you have water at an avg temp of 110 for a good portion of the panel. In the other case, you have water at 65 deg for a good portion of the panel. I think that portion of the panel is large enough that this temp difference makes a significant difference in how much water evaporates. In the case of using the 130 deg water, how far down the panel do you think the water goes before it reaches the steady state temp?
Also, regarding evaporation rates and temperature, it's well known that water evaporation rates over the tropical oceans are significantly higher than they are over cooler oceans. If water temp has only a negligible effect on rates of evaporation, how can this be? The ocean temps vary by far less than the 130 deg vs 40 deg we have with the humidifier example.

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<%-name%>
• posted on February 10, 2009, 11:21 pm
snip

OK we agree that you need a certain amount of heat to evaporate say 1 gallon of water and that heat has to come from either the furnace or the hot water heater... ok..
You think it's not

I agree that the hotter the water IS in the panal, the faster it evaporates..
I think we disagree on this part.. I think (similar as Bubba) that if you feed hot water, it will cool off very quickly as it starts to evaporate.. in other words the initial heat energy in the hot feed water will be used up fast since it's only 10% of the total needed... and after that inital 10% energy is used up, the water will be the same temp (and evaporate at the same rate) as it would if cold water fed in at the top. I think your estimate that the water will take 1/2 the panel to cool is wrong becasue you have to remember that evaporating water sucks up a very large amount of heat. So 8000 BTU are needed to evaporate a gallon. And the hot water supplies an extra 800...
So I thik we agree that the water temperature DOES indicate how fast the water is evaporating, but we don't agree how hot the water will be in the panel. This make the experiment easier if you want to do it. You just have to determine the water temp in the panel... I think it will be nearly the same regardless of how hot the feed water is. The temp of the water in the tray will be determined by the furnace air temp and how fast the air is blowing etc. As you said it is complex... but from an energy point of view.... we know you need a total of 8000 BTU to evaporate a gallon. The feed water being hot to start with supplies only an extra 800 BTU. The remaining 7200 BTU still has to come from the furnace.
I also agree it is complex, things like the size of the spray droplets and the air and all kinds of things effect how fast the water will evaporate. But in the end 8000 BTU will be consumed per gallon and I think an extra 800 BTU head start still amounts to only 10% improvment.
If you were blowing air at 500 miles per hour, yes a lot more water would evaporate a lot faster but the 800 BTU from the hot water feed would just get used up that much more quickly...it's still 10% of the total per gallon..
Think about the clothes dryer analogy. You put in clothes that are wet. In one case the clothes are wet with hot water. In another they are wet with cold water. After a short time, the hot water clothes are going to be nearly the same temp as the cold water clothes. And we agree that the temp effects the rate of evap so if the temp is nearly the same, the rate of evap is nearly the same.
I think the thing you are stuck on is the hot water is heated only once. If you could put the hot water heater ELEMENT in the humidifer so you could add lots and lots of BTU all the time, as the water evaporated and used them up you could replace them from the element ...then YES I would agree with you it woould make a big difference. But that's not the case we have here. The water is heated only one shot and therefore it can carry about 800 BTU per gallon and that is only about 10% of what is needed to evaporate it..
OK???
And I want to thank you for having a civil discussion without name calling... Many folks on newsgroups can't seem to do that.
Mark
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<%-name%>
• posted on February 11, 2009, 12:23 am
On Tue, 10 Feb 2009 15:21:06 -0800 (PST), snipped-for-privacy@yahoo.com wrote:

Mark, And I respect your civil discussion as some of us (me) have a little bit harder time with that but.................. WOW! If you look this thread over and see how long its been going and for someone thats in the business (like me) that has installed hundreds and hundreds of humidifiers of all types over the years and purposely did the test I have described over and over to trader and he refuses to do it but just keeps guessing and spitting out wrong info it just gets a little overbearing for me. Im not one to let wrong info go by the wayside when Ive actually done it for myself. Anyways, thats my story and Im sticking to it. Bubba
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<%-name%>
• posted on February 11, 2009, 12:16 am
On Tue, 10 Feb 2009 06:35:42 -0800 (PST), snipped-for-privacy@optonline.net wrote:

Hmmm, trader. For someone that claims to not understand me, now all of a sudden you want to quote me. C'mon. Make up your mind.

There you go again. Your comprehension level seems to be dropping like a rock off a cliff, trader. NEVER, did I say it was free. More concret for that block-head of yours?

I still say you are wrong trader. Why make the water heater come on and heat the tank back up when the furnace already has to run? Again, Im not saying its free but more practical and more efficient.

Yet you refuse to test the results for over a month or more now but instead just keep flapping your yapper, trader. Prove me wrong.
Just for the heck of it, do you understand the venturi effect? What do you think happens to that water right where it reaches the orifice? Its shot into that tube where it loses even more temperature. Again, try it and test the temps and measure the water coming out of the drain tube. Oh forget it. You never will.

No trader you dipwad. You're making up shit again. I never said it cooled complety. I say that by the time it has reached the distribution tray and starts to drop through, it has cooled considerably. Then as soon as the air hits it near the top of the pad the temp is pretty much dropped to room temperature. Got it now? Do I need to draw you a picture or do you need another bag of concrete for your block-head?

Maybe, sort of, could have, I think, could be, etc. etc. etc. Maybe monkeys will fly out of your ass too but I really doubt it.

discussion? yeah, thats just great trader. Anyone can make up shit. I seem to know someone else in here that flips numbers out like that. Is that how we need to classify you know?

Hey trader. How about we just stick with the humidifier for now and leave the temperatures of the ocean alone. I think this humidifier experiment is way over your head as it is. Maybe you and Al Gore can have a discussion about the hole in the ozone too. Bubba

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<%-name%>
• posted on February 11, 2009, 12:32 am
On Mon, 9 Feb 2009 20:25:48 -0800 (PST), snipped-for-privacy@yahoo.com wrote:

Mark, I guess I wasnt really asking a question even though I started the sentence of say "Im just asking..." I think really I was just stating what I see happening. What Id really like to see is someone like Aprilaire show me just how much water is being evaporated using hot water. Actually Im meeting with my Aprilaire rep on Friday for breakfast. I'll see if he can get one of the higher ups at Aprilaire to get me some kind of facts or written info on the use of hot water with humidifiers.

Yeah, maybe a better explaination would be using an oil fired hot water heater to heat water as opposed to using a gas furnace to heat the air and transfer that heat to the water. I know I didnt bring up that scenario but trader acts like it doesnt matter how you do it. One way or the other it costs almost the same. I disagree. Thats why I brought up the jet engine heating the cup and a small torch (or whatever I said). Maybe just maybe that explaination makes it a little clearer? I doubt it for someone here though. Bubba
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<%-name%>
• posted on February 11, 2009, 1:11 am

I think you and Trader actually agree in principal that using hot water makes at least some small difference. Trader thinks it makes a big diff and you (and I) think it makes only a little diff. My rough cut math says its about 10% and you would never notice that without some kind of measurement.
It would be interesting to see if the rep from Aprilare gives you a number.
I also think we all agree thats it's a matter of the water temperature inside the humdifier.., if Trader can agree (or measure) that the water temp is about the same, then we can all go have a beer.
Mark
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• posted on February 11, 2009, 2:49 am
On Tue, 10 Feb 2009 17:11:08 -0800 (PST), snipped-for-privacy@yahoo.com wrote:

hehe. Yeah, that would be a sight. I certainly will ask the rep and push him to get me an answer but in all honesty, I dont think I will get any definite number answer. Bubba
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<%-name%>
• posted on February 10, 2009, 1:46 pm

Huh?
Your science gets worse by the minute. Whatever heat it takes it has to come from somewhere. If the heat is provided by the furnace then there is that much less heat available to raise the temp of the air. It's heating water instead of air. If it's provided by the water heater, then the energy comes from the gas burned in the water heater. We already went through that and you compared it to heating a cup of water with a propane torch vs the exhause from a jet engine. Which of course is ludicrous, because those two are nowhere near as efficient methods, so of course there is a huge difference. In the case under discussion here, heating water whether in the water heater or via the furnace is in the same ballpark in efficiency.

Who cares whether it's 120 or 150. The obvious point is that it's a lot higher than 40 or 50 deg deg cold water.

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<%-name%>
• posted on February 10, 2009, 11:58 pm
On Tue, 10 Feb 2009 05:46:15 -0800 (PST), snipped-for-privacy@optonline.net wrote:

Now you're making sense. :-)

No, actually your reasoning gets worse and worse. It comes from having a head made of concrete and believing everything someone writes on a piece of paper and you read it. Tell me, you dont believe everything you read on the internet, do you? Yes, we did go through this and you act like providing humidification by either heating water with a water heater or providing it with a furnace is the same. Thats just plain ignorant of you. There are better, more effective, efficient ways to do most everything. You happen to be wrong but cant live with yourself knowing you screwed up.

Oh, so now heating water to 120 degrees cost the same as heating it to 150 degrees. Must be that universe you were talking about that you just landed in. Bubba

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• posted on February 6, 2009, 3:43 pm
I had a steam generator installed on a new heat pump/electric zone and the moisture ruined the coils, enclosure,etc. Currently have an April Aire (and of course a new air handler) which drains excess water to a summer condensate tank with a float switch operated pump which pumps the drain water up about eight feet through a loop and a check valve into a grey water house drain system. I have not found any of them to be great in this house which is rather large.
borealbushman wrote:

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• posted on May 12, 2015, 2:46 pm
replying to borealbushman, Steve's Heating Gaylord Michigan wrote:

I have been in Residential HVAC for 30yrs, Most of them servicing geothermal......
The output of any humidifier is based on having a minimum temp of air going across the pad/panel etc , the warmer the air, the more water it can hold, which equals the more moisture it will evaporate in a single pass. Geothermal units operate at lower outlet temps than gas fired equipment, therefore you need to select a humidifier which been manufactured to add more humidity at these lower temps.....there are many ways in which they operate, (steam, fan power assist, direct mist etc...) All of these have specific operating conditions, such as existing duct layouts, (to prevent water accumulating on duct surfaces etc)..... so be sure to hire a company with experience with these special humidifiers, because if the requirements for the installation of these units aren't met, at the very least, they may cause damage to the equipment. Uncontrolled water contact can cause indoor mold issues.