Humidifier Question

[Ace]

You can say what you want about humidifiers, but I had an Aprilaire 600 installed on my new Carrier furnace return air duct and (my new ranch style home is 2,880 sq feet) since I did my throat is not dry and sore every morning I get up and I don't have hock my socks off to clear out my throat. Also, static electricity has been eliminated in my home. I also think that my gas bill will be cheaper with proper humidification. I disagree with you who say home humidification is a farce. Of course one should not over humidify and have their windows all steamed up and their walls dripping with condensation. Common sense comes into play.

[nicksanspam]

Thanks Ace. They waste energy.

I disagree. Perhaps you have no understanding of physics.

I never said that. Perhaps you have no understanding of English :-)

Have a nice day.

Nick

[Gary R. Lloyd]

Since you seem to love math (I can do it but I hate it), let's give you a little challenge:

Let's assume the same house. The indoor conditions are to be maintained at 70F and 40% RH (because the homeowner likes it that way). This translates to an indoor dewpoint temperature of about 44F. When the outdoor dewpoint drops below 44F, that 160CFM of infiltration air will need to be humidified, right?

But wait, we have our family of four providing 2 gallons per day of humidity. Thus we can drop to a lower outdoor dewpoint before extra humidification is needed for the infiltration air.

So here is the mission, should you choose to accept it:

At what outdoor dewpoint temperature do we need to start adding moisture in order to maintain our 70F and 40% RH?

What if the house were half the square footage (1200 sq ft)?

Gary R. Lloyd CMS HVACR Troubleshooting Books/Software

[nicksanspam]

Td = 530/(1-530ln(0.4)/9621)-460 = 44.5. Pi =0.4e^(17.863-9621/530) = 0.2994 "Hg... wi = 0.62198/(29.921/Pi-1) = 0.006286 pounds of water per pound of dry air.

Somehow...

2x8.33/24/60 = 0.0116 lb/min.

Sure.

When 160x0.075(wi-wo) < 0.0116, ie wo < wi - 0.000966 = 0.005319 and Po = 29.921/(0.62198/wo+1) = 0.2357 "Hg and Td = 9621/(17.863-ln(Pi))-460 = 40.2 F.

When 80x0.075(wi-wo) < 0.0116, ie wo < wi - 0.001933 = 0.004353 and Po = 29.921/(0.62198/wo+1) = 0.2079 "Hg and Td = 9621/(17.863-ln(Pi))-460 = 35.1 F, if it has half the air leakage.

Nick

[Ace]

[Gary R. Lloyd]

Hmmmmm... Considering that our family of 4 needs 15CFM of fresh air each, for a total of 60CFM, I don't think we want to tighten a house up much more than that.

Just for a rough rule of thumb:

It seems that when outdoor temps start dipping below freezing at night, our options are to humidify or to accept lower indoor humidity.

On the other hand, if our humidity drops below 40% before the outdoor temps drop below freezing at night, then we need to seal up the house.

Does that sound about right?

Gary R. Lloyd CMS HVACR Troubleshooting Books/Software

[nicksanspam]

I think we do, with positive ventilation as needed.

Nick

[Gary R. Lloyd]

When it comes to something as vital as providing sufficient air to breathe, I would lean heavily towards passive solutions and overkill, i.e. leakage. It's about human health and comfort. Screw the energy efficiency.

People in dry climates are acclimated to their environment, and thus would have no problem with low humidity. People who suffer through high temperature and humidity throughout the summer are not equipped to put up with low humidity in the winter.

Besides, my grandmother's antique dining room set doesn't like low humidity, so that settles it.

Gary R. Lloyd CMS HVACR Troubleshooting Books/Software

[nicksanspam]

You've seen 'em.

Nick

[nicksanspam]

I wonder why you wrote that. Another option is air sealing to raise the RH. BTW, we've only discussed the outdoor dewpoint (vs. dry bulb) temperature.

Air sealing is good in any case. "Make it tight, and vent it right."

Nick

[nicksanspam]

Spoken like an HVAC criminal :-) But we can enjoy "human health and comfort" with less energy consumption if we do air sealing first. It would be extraordinarily difficult to seal up a house so tight that a person could not breathe. And most people would open windows as needed to avoid condensation and lower the indoor RH. That's also easy to do with a small exhaust fan and a humidistat.

Herbach and Rademan [phone]

sell a nice brass $4.95 Navy surplus humidistat, item number TM89HVC5203, with a

20-80% range, a 3-6% differential, and a 7.5A 125V switch that can be wired to open or close on humidity rise.

In what sense? How do you know? Where is your evidence? Then again, living with low humidity is only one option. It's better to raise the RH and lower the fuel bill with more air sealing.

Is it better to airseal your house to assuage the feelings of your grandmother's antique dining room set, or humidify the house and dramatically increase the fuel bill and invade Iran to keep the price of oil low? :-)

Nick

[Gary R. Lloyd]

Show me.

Seal up the house and then open the window? Oddly enough, I think that's what a lot of people do.

And if the control fails?

I have no intention of proving anything.

Actually, I'm a big fan of sealing up the house, but I draw the line at putting a plastic bag over people's heads.

Let's try to stay on subject, shall we?

Gary R. Lloyd CMS HVACR Troubleshooting Books/Software

[Gary R. Lloyd]

Hence calling it a rough rule of thumb.

To a point.

Our energy-is-all-that-matters geniuses have given us lots of unintended consequences, such as sick buildings and enormous mold problems (which they are trying to blame on contractors). What next? As far as I am concerned, they are fast losing their credibility.

Gary R. Lloyd CMS HVACR Troubleshooting Books/Software

[nicksanspam]

Done that, several times now.

Oh?

We suffocate like dogs.

Good idea. Perhaps you recall your last attempt at proving something, in which you confused dew point and wet bulb temps :-)

People are different. Avoiding Middle-East wars is a primary motivation for using less fossil fuels, in my case.

Nick

[~^Johnny^~]

I see a pun here, but I will desist. :-)

You both have valid arguments. But I agree, caulking generally doesn't do shit for infiltration control.

Caulking and weatherstripping has to be evaluated on a case-by-case basis, but generally, it is a marketing ploy.

I don't keep my doors and windows shut 24/7.

[HvacTech2]

Hi Zypher, hope you are having a nice day

On 13-Nov-04 At About 03:31:39, Zypher wrote to Zypher Subject: Re: Humidifier Question

Z> From: "Zypher"

Z> Hi Nick;

Z> Here's a link for you to read up on [albeit consumer literature but Z> it drives the point well.]

Z>

it doesn't do any good to show him the truth. This guy is a legend in his own mind and doesn't believe anything other then what he thinks.

-=> HvacTech2

[Gary R. Lloyd]

You forgot to show me the health and comfort part.

Is this an example of showing me?

I didn't confuse anything. I offered a rough rule of thumb based on DB, and said it was a rough rule of thumb.

Wars are a diversionary tactic. "LOOK OVER THERE. ITS A WAR" (insert hand remove wallet)

Gary R. Lloyd CMS HVACR Troubleshooting Books/Software

[nicksanspam]

That's your job, as a higher-humidity proponent. You've seen the comfort part (ASHRAE 55-2004) several times now. I'm not sure health has much to do with low humidity. At any rate, unlike mechanical humidification, air sealing can raise humidity while lowering vs raising fuel bills.

No. This is an example of humor.

That was this time. Last time (in August of 2002) you confused dew point and wet bulb temps. It's surprising how little hvac "tech method gurus" know about physics.

Chacun a sa guerre.

Nick

[Gary R. Lloyd]

You are the one who wants to seal people up in a bubble and pump in the air. It is up to you to show us that it is healthy and foolproof.

As was my response to it.

The two are close enough to be considered the same for practical purposes, but then you are not concerned with what is practical, so we can't expect you to understand.

Funny article. Well written.

Gary R. Lloyd CMS HVACR Troubleshooting Books/Software

[Joel M. Eichen]

Low tech way of getting humidity into the air and saving on heating bills!

A pan of water near the heating duct .......... over it, under it, whatever ...... near it.

Joel