Where to install flow through humidifier on electric furnace.

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Old 01-15-11, 01:08 PM
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Question Where to install a fan powered flow-through humidifier on electric furnace?

Where's the best place to install a fan powered flow-through humidifier (Honeywell HE360/365 or Aprilaire 700) on an upflow electric furnace/heatpump?

The install manuals say the supply (output) flow is the best spot, which would be above the heating elements. However, a furnace tech that was out to help with the stat (Honeywell Vision Pro IAQ) said they don't like to install over the heating elements as water could drip onto the elements damaging them. They like to install in the return air line, which would humidify (in order) the filter, A coil, blower, and heating elements.

This seems a little less than desireable to me as I'd be dumping humid air onto my pleated furnace filter so any dirt on there would become sorta mud I'm assuming, and I don't feel subjecting the heating/cooling elements and controls to that direct moisture from the humidifier is a good idea. I could be wrong though, it's happed before....

I'll be having the IAQ control the humidifier vs using a separate humidistat.

6 mo old Tempstar 15kw electric furnace, variable speed blower, Honeywell Vision Pro IAQ stat, 14 seer 3 ton HP.

Anyone with suggestions?

Thanks.
 

Last edited by ckspeed; 01-15-11 at 02:56 PM.
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Old 01-15-11, 04:51 PM
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No, the humidity is not going to make the filter wet/mud.

The fan powered unit are best to be on the supply side of system for heat to help it. Why not do the bypass unit? That can be mounted on the return since it's getting the hot air from the supply side.
 
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Old 01-15-11, 05:34 PM
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Thanks for the info!

Is the bypass a better option than the fan powered? I was under the impression fan powered was the way to go, especially with my equipment. I would rather not bypass any of my supply air back to return thus reducing any airflow.

My only complaint I can see of the fan powered would be the need for a dedicated or close 120VAC outlet. I'd like to be able to wire it into the furnace circuits, but that may be a no-no.

Is there really a problem with mounting it in the supply? I can't see how water would "drip down" on the elements anyway.

Thanks.
 
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Old 01-16-11, 09:54 AM
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I never seen any drop in air flow with bypass unit.

Only time water would get into the air handler is if the drain wasn't clean, pad was plugged or what not that cause the water to go outside of it's normal area.
 
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Old 01-16-11, 10:19 AM
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Okay, well that makes sense. So, assuming I keep an eye on things and don't have the "set it and forget it" attitude, is it a generally a bad idea to install the powered unit above the furnace?
I'm very good at remembering to change filters, pads, etc. and have a pretty good maintenance routine down.

From the pics, it doesn't appear water would actually be IN the plenum, but just outside it anyway. I would only assume if it were to leak that it would most likely leak outside the unit, not into the plenum and on top of the heating elements. Maybe the housing could be modified to accept a water alarm or at least a drain to prevent damage.

In either mounting position, can it be wired into the furnace electric supply circuits or would it have to be plugged in?

Any opinion on the Honeywell HE360/365 vs the Aprilaire 700?

Thanks again for the advice.
 
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Old 01-16-11, 11:32 AM
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It would take a lot of water to get on the coil. If it was an issue, it would be outside along the side inside, and if it' mounted on the front of the unit where the wires/control are under the humidifier, then water can get into the controls.

If you are good about maint. then you should be fine.

Humidifier is a humidifier, and they are all pretty much the same. Just what is being used for control that may matter.

Most honeywell will come with the basic control, and Apirilaire has digital control, and be wired to an outdoor sensor. I like the outdoor sensor cuz it can control the humidity level with the outdoors temps, so that way you don't have to make the changes all the time. You could upgrade the humidistat from Honeywell to TrueIAQ control.
 
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Old 01-16-11, 11:49 AM
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I'm planning on using my Vision Pro IAQ w/outdoor sensor to control the humidifier so I shouldn't need another controller.

Any thoughts about the wiring?
 
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Old 01-16-11, 01:28 PM
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Ok, then either one would be fine.

Wire hook up very easy for the Honeywell. Just hook up the two yellow wires to the HUM.
 
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Old 01-16-11, 01:52 PM
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The honeywell would be easier to wire than the AA. The AA uses an external transformer that needs wired up.

Other than that they are pretty much the same unit.
 
 

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