Humidifier Effectiveness

MarkC

Hi all,

I have an Aprilaire model 350 whole house humidifier which seems to be ineffective.  It runs almost constantly with the humidistat set at only 25% and the humidity level measured by a separate hygrometer rarely measures higher than 32%...right next to the humidistat (measurement inaccuracies assumed).



The humidifier is located in the basement and controlled by an Aprilaire humidistat in the living space on the first floor.  The humidifier is not mounted on ductwork - it is a standalone type and draws air (intake) from the basement. The outlet (1) is a floor register on the first floor.  The entering water temp is about 103 degrees and the intake air (basement ambient) is about 64 degrees.



My question is - would the humidity output be increased if the intake air was higher?  Is the 64 degree intake air 'cooling' the water in the humidifier's water panel and defeating evaporation?

BillW

Humidifier

Too possible issues come to mind.  The unit may be undersized, so it doesn't have enough capacity.  Between 40-60% is where you want your humidity levels.  Below 40 and woodwork or hardwood floors may be damaged, static electricity may be annoying, and you may have dry eyes, nasal passages and skin.  Above 60 may lead to wet widow sills from condensation, possible insulation failure caused by condensation inside walls or a mold problem.

 The other is If the incoming water is not warm enough, and the ambient air isn't warm enough, you won't get proper evaporation. Your home may also have lots of air leaks, but only a blower door test will prove that. 

Jean-David Beyer

I am surprised.

I have a little humidifier with digital controls. I was running it at 35%, but it got very cold (7.5F) last night, so I noticed some condensation on my fancy Marvin windows. I have a Radio Shack hygrometer that agrees pretty much with the humidifier. I cut it and the condensation disappeared. The temperature, by that point, went up to 20F, so it is not clear if I lowered it enough. On the other hand, I cannot lower the humitifeir below 30%.



I know it would normally be desirable to keep the relative humidity between 40% and 60% for many reasons. But in such cold weather, I do not want condensation on the windows. Since my walls are real plaster, I doubt as much humidity leaks through them as would leak through dry-wall, but I would not wish to risk it.



The forced air furnaces that heat a large leaky building I know have Honeywell humidifiers that have been set to 30%; the contractor advised against going over that. Is there a rule about this, or is it to run as high as you can, short of getting condensation?

BillW

Humidification

The 40-60% range is a guideline.  Don't forget, you add humidity every time you take a shower, boil a pot of pasta, or hang-dry laundry. A tight house allows humidity from any source to reach equilibrium, a leaky one does not. My house runs at about 35-45%, and it was 0 here this AM, and I had a slight bit of condensation on a few of my Anderson windows, but nothing radical.  The air is very dry on bitter cold days, heating it up drys it out even more, so some additional humidification is needed for comfort.  This winter has been colder than it has been for quite a few years, so some unusual results may occur.

thomasc

humidifier

I think that humidifiers are indeed helpful and makes sure that you get a better ventilation in the area.  Though there are a lot of risks these humidifiers post to health.  For one, if you live in a place where there are a lot of insects they can use the area with water as their breeding ground.  While that sounds a little too paranoid for you, that poses real danger.



The other one, some humidifiers affect the health as they blow mists that can hold viruses as they can be stagnant water.

JStar

Problem

The humidifier is not mounted on ductwork - it is a standalone type and

draws air (intake) from the basement. The outlet (1) is a floor register

on the first floor.







There's the problem. It's not really a whole-house humidifier right now.