Whole house humidifier questions. 2

[jjStowe]

I have a forced air funace and a GreenTek air to air exchanger in my house and want to install a whole house humidifer, I'm thinking the Honeywell HE260 Bypass Flow Through Humidifier.

My question is this: The air to air exchanger is controlled by a humidistat mounted by the thermostat, is there a way to control both the humidifier and air to air exchanger from the same humidistat?

Or if I have to install a new humidistat for the humidifier will it and the air to air exchanger fight to add/remove moisture? I don't want to create an issue where they are both always running becuase they counteract eachother.

Sorry if this is dumb question, appreciate any insight you may have.

 

[tys90]

I would put a separate humidistat in at the same location of as the GreenTek humidistat or, ideally, move the Greentek humidistat to the return air stream and put both humidistats there. Theoretically, the setting on each one should be so they don't fight each other. Depending on where you live you don't want very high humidity in the winter to prevent condensation and the air to air exchanger probably won't be able to get the air dry enough to start the humidifier in the summer.

That's my opinion.

 

[willard3]

If you humidify too much, the air-to-air heat exchanger will frost up under low OA temperature conditions and stop working.

 

[ChasBean1]

jjStowe, without reading all of the technicals about this model, I’m skeptical about the performance of this heat recovery unit running based on a humidistat during winter. In the winter, you’d want the heat recovery to run based on temperature. Indoor might read 20% and outdoor might be 75% while actually being much drier due to very low dry bulb temperature; unless the heat exchanger is looking at actual dew point or mass of water per unit mass of air…

To make this work right, you’d really want the HX operation to look at the OA temp; if below 50°F or above 80°F, run heat recovery. If it wants to get fancy and run an enthalpy comparison, do it during summer but not winter.

Your humidifier should control independently of the heat exchange function and should operate based on humidity of air going back to the heat exchanger (prior to it), but be limited by a separate discharge air high limit humidistat located in the supply duct, downstream of the humidifier, that prevents excessive humidification/condensation (typ. set to about 85% RH). I’d suggest a set point limit of about 30% RH in the exhaust air, unless you have really good building envelope, modern double pane windows, up-to-date walls/insulation, etc…

 

[ChrisConley]

Any particular reason you want to add the whole house humidifier? I've yet to encounter a residential humidifier (or commercial for that matter) that hasn't been shut off or just stopped working after a few years.

Typically residential activities (cooking, bathing... breathing) add a fair bit of moisture to the house.