# Bypass Humidifier goes before or after air filter?



## key1cc (Nov 21, 2008)

When I opened my blower door on my XV95 furnace (to look at my pressure manifold) I noticed there was a lot of debris on the bottom of the return drop. After inspection I realized it was coming from my bypass 
Humidifier pad which was positioned after the filter in my case. I immediately repositioned the Humidifier to a position before the filter so if the humidifier pad further deteriorates, at least the particles will be captured by the filter. 

I have a horizontial filter installation in my return drop.
Below are pictures of the Humidifier positioned post filter (below filter) then later positioned before the filter (above the filter).

Hopefully the issue is solved and I did not inadvertantly create another issue. Does anyone think there would be a problem with the Humidifier in the new location?

Thanks 

Key1


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## yuri (Nov 29, 2008)

Da humidistat is in the wrong place now. It needs to sense the return air B4 it gets to the point where the air enters from the humidifier. Relocate it to the horizontal RA duct. The rest looks OK.


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## key1cc (Nov 21, 2008)

yuri said:


> Da humidistat is in the wrong place now. It needs to sense the return air B4 it gets to the point where the air enters from the humidifier. Relocate it to the horizontal RA duct. The rest looks OK.


Thanks for pointing that out, however my humidifier does such a poor job I always leave it all the way on so that it runs whenever the heat is on nonstop. I did not bother to cut the hole behind the humidistat since even at full power when it is 20F outside with 80% outside humidity, the best I can get inside is in the mid 30's.

Key1


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## key1cc (Nov 21, 2008)

Also, below is a post in blue font that I had put on one of the Pro sites (non-DIY), that shows some data I generated. The outside temps had went into the 60's and it was raining so we opened the windows were able to get the humidity up into the 40's....
maybe I'll get better insight here.....

"I have a Trane Bypass Humidifier Model D200, which I believe is very similar to the Honeywell H220 or the Aprilaire 500 models.

After reading through some threads on Bypass Humidifiers I decided to check the water flow and usage as one of the Pro's had suggested.

I simply collected the water from the outlet for exactly 1 minute using a timer and weighed it on my digital scale. I did it twice to make sure, and both numbers matched exactly at 309 grams.

Next I took the Humidifier cover off where the pad is located and pulled out the inlet hose and let that water drain for exactly 1 minute into a cup again in duplicate to insure values were accurate. The number was 342 grams.

309 grams per min for 60 minutes = 18540 grams = 4.9 gallons/hour.
342 grams per minute for 60 min. = 20520 grams = 5.4 gallons per hour.

5.4-4.9 = 0.5 gallons per hour transfered into the air stream which is exactly what the evaporative capacity spec states that it should be.

What was quite suprising is that the unit puts 4.9 gallons of water down the drain for every 0.5 gallons it puts in the air....or said another way, it only utilizes 9 percent of the water for humidification and wastes 91%








Did I miss something? Is this how the units are designed?
Is it possible my water flow is too high?

Additional notes:
My unit is hooked up to the hot water.
The incoming water was very hot, the outgoing water was very cool indicating as someone suggested, the heat is transferred during the humidification process.
Thanks in advance.

Key1


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## kennzz05 (Nov 11, 2008)

wow youve got too much time on your hands! yep thats they way they work sad but true. only a couple of ways around it without reengineering your current humidifier(which im guessing youre thinking about) steam type and the drum type. drums are ok if you clean the tray every 15 to 30 days otherwise they can form mold from stagnation. they do however work very well and there cheap. They reuse the water and only fill as needed. Steam work very well too but they tend to be troublesome and expensive to operate. stay away from spray types they do work well however its at a cost of rotting ductwork from the direct dousing of water


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## hvaclover (Oct 2, 2008)

Why did you put the the ac drain trap on the humidifier?


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## beenthere (Oct 11, 2008)

Don't know about that humidifier.
But, with Aprilaire, you can install smaller orfices, that reduce the amount of wate water.

The waste water, is also the water that keeps your pad clean from excess build up.
Its a catch 22, if it didn't have that waste water, it would scale up before the heating season was over. So its capacity would drop.

At 20°F outside temp, you don't want 40% RH, your windows would sweat.


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## key1cc (Nov 21, 2008)

kennzz05 said:


> wow youve got too much time on your hands!


Yep.
I have a couple more days of vacation this year. (Use them or loose them). Trying to get things done around the house.
Thanks for the feedback.

Key1


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## key1cc (Nov 21, 2008)

hvaclover said:


> Why did you put the the ac drain trap on the humidifier?


I thought I read it on the HVAC-Talk site.:confused1:
The pro that suggested it indicated "to not do it was like having a 3/4 inch hole leaking conditoned bypassed air".

Perhaps I mis-interpreted?
I did not cement it yet so it can easily be removed if there is no benefit??

Key1


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## key1cc (Nov 21, 2008)

beenthere said:


> Don't know about that humidifier.
> But, with Aprilaire, you can install smaller orfices, that reduce the amount of wate water.
> 
> The waste water, is also the water that keeps your pad clean from excess build up.
> ...


I think I'll live with it for now.
Just wanted to get a better understanding of where my energy usage is coming from since I am tapped into the gas hot water heater.

Key1


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