Two stage Furnances, Modulating Furnances with Wood Heat?

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.

Pertzbro

Feeling the Heat
Aug 2, 2016
330
NW Iowa
My AC crapped out on me and it needs to be replaced. Being that its a 23 year old set I'm replacing the entire HVAC system.

I like the idea of the new multi stage furnaces. I'm on propane. However, when reading about how they work i feel that my supplemental wood heat will mess up the furnance's computer system and i wont get the full benefit of multi-stage furnances.

Should I stick with the old tried and true single stage (off or on) or will I see benefit from a multi-stage unit?

I believe the options i will be choosing from our single speed blower, single level heat (full on) and a single speed blower and two stage heat.

I guess this discussion could include modulating (multi speed blowers and multi stage gas heat level) and how wood heat may mess up the computers in those furnaces as well.

Am I over thinking this?

I rarely can get by with only wood heat. We're often away from the home from 8am to 6-8pm and i cant get a burn to last that long. I usually have fires from 6-11pm 2-3 nights a during the work week and let it go out sometime around 4am. I do however try to burn 24 hours from Fri night through Monday around 3-4am (whenever the last load on sunday night burns off)

Thanks
 
The multistage units are nice. They are quieter and more fuel efficient. A 2 stage unit should work fine. If the furnace is just working to supplement then it may just come on at half-heat and half blower speed. I don't think the simple computer will get confused as long as the thermostat is not too close to the stove room. Some also measure outside temp which helps determine how much heat is needed and how quickly. Usually these units have a digital 7 day thermostat that will have a weekend mode. You could set that up to a low temp of say 60º if you don't want the furnace to come on at all during that period.
 
yup also agree get the modulating heat option. when not at home or you get to tired or to old to lug wood around you are all set..your wood heat should not do anything to how the furnaces run. some of the computers in the furnaces or after market computers have a in coming air sensor to the furnace or in the living space to help regulate even better. also get set back thermostats to have your heat come up at 4 am so you don't wake up cold. the set backs have 4 setting per day.
 
Last edited:
I'd go with a multistage, and even wire in a second state if it's near your stove. That way the stove heat won't mess with your computer, not that I think it would anyway.