Bypass humidifiers and AC cooling coils: what is the concern?

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Old 10-18-09, 08:24 PM
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Question Bypass humidifiers and AC cooling coils: what is the concern?

I am thinking about installing an Aprilaire 400 whole house bypass humidifier but have space issues on my supply plenum. Basically, the AC coils go pretty much all the way to the top of the plenum (it looks like there is a large radiator at a 45 degree angle in the plenum, it's not A-shaped as other have reported).

What is the main concern with installing a bypass humidifier at about the same height as the cooling coils? Is the main concern damage to the coils? I have a fiberglass plenum so I can take the side of the plenum off to work on it ensuring that the coils will be untouched. Let me know.

BTW, the reason I was going for the Aprilaire 400 is that I do not have a drain in my basement so a flow through unit is not an option. I guess I could handle the flushing cycle of a truesteam with my condensate pump but the 0.20$/kwh we pay in Westchester NY would make the truesteam very expensive to own.

Thank you,
 
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Old 10-18-09, 08:46 PM
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I'm not sure "Hot water boilers" is quite the right forum for your question... I'm gonna look and see if there is a better one, and might move it if I can find one.

OK, here ya go, "Humidifiers and Dehumidifiers" ... seems to be just the ticket!
 
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Old 10-20-09, 03:22 PM
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Are you able to mount the humidifier on the return duct?

Post a photo if you can so we can see what's going on.
 
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Old 10-20-09, 07:12 PM
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There is a quick picture of the setup. You're gonna have fun with this one. It looks like my 15-months old put it together.



There is an AC radiator going from the top left to the bottom right. I was thinking about installing the aprilaire 400 on the left side in between the furnace and the top of the 45 degree AC radiator. Installing the humidifier on the return ~10 feet from the furnace would be a possibility but is not recommended by aprilaire. It is not a flow-through humidifier so you cannot use heat from hot water for the evaporation. You need the furnace.

Coming back to my initial question, what's the issue with a bypass humidifier next to the cooling coils? The flow should be good and the humidity goes to the return so it will go through the coils anyway.
 
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Old 10-20-09, 09:09 PM
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That's an older furnace.. About 20 years old.

If you can clear the coil on the left side on top, go for it... Where are you going to put the by pass duct at?
 
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Old 10-21-09, 10:34 AM
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The house was built in 1988 so it must be the original furnace. It surprisingly high efficiency for its age.

Just to clarify, the humidifier will be in between the top of the furnace and the top of the radiator. There should be a few inches of clearance between the radiator at 45 degrees and the top of the humidifier (the clearance being larger at the bottom of the humidifier).

The return is on the bottom right. I have about 10-11"" of clearance between the right wall and the furnace so I should be fine for a 6" bypass duct to the return.
 
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Old 10-21-09, 04:03 PM
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Originally Posted by tymon View Post
Just to clarify, the humidifier will be in between the top of the furnace and the top of the radiator. There should be a few inches of clearance between the radiator at 45 degrees and the top of the humidifier (the clearance being larger at the bottom of the humidifier)..
Radiator? You mean the A/C coil, or the furnace heat exchanger?
 
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Old 10-22-09, 12:41 PM
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Well the A/C coils look just like a car radiator. Who knows, maybe it is a car radiator ;-)
 
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Old 10-22-09, 01:01 PM
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Ok. Just making sure..

Just watch what you are doing so you don't damage the coil, and you should be good.
 
 

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