2 forced air furnaces, what thermostat

TheKeymaster

I'm closing on a house on jan 19. The house has 2 forced air furnaces both located in a basement room if that matters. The rest of the basement is finished also besides this one room. Each floor is around 2200 sqft and each furnace feeds one floor. The floors basically consist of 3 bedrooms a living space, 2 bathrooms, and a kitchen each. There's no kitchen in the basement. The furnace/mech room is the room that is below the kitchen. The floor plans match exactly pretty much besides a few little rooms like laundry room. So for reference it's basically a ranch and a half or upside down ranch they call it sometimes. There is one simple thermostat on each floor for the furnace that feeds that floor. I want to change the thermostats to 5/2 ones at the very least. Maybe even smart ones as I'm bringing many smart items from my current house with me. Is there some 2 thermostat system smart or otherwise that I can use? Like I have a remote thermostat in the basement that can be controlled by a main thermostat upstairs that could control the upstairs and downstairs furnaces from one location. We will keep the downstairs one lower because it won't get used as much. I'll just turn it up when I think it might get used. How much will the thermostat downstairs affect the one upstairs?

STEVEusaPA

Well the thermostats don't affect each other. If both areas are thermally isolated, they will just run independent of each other. However, if heat is allowed to migrate from one unit to the other (heat moves to cold), then one unit will obviously run more.
Also if the 'zones' (systems) aren't isolated, the blower from one unit can pull in colder air from the other zone if the ductwork, especially returns aren't designed properly.
But to keep it simple, you could put remote sensors on each floor, one per thermostat, and put the t'stats in the basement.
Honeywell makes thermostats that will do that, with or without wifi.
If you want to get more sophisticated, you can bump up to some more commercial controls that could manage both systems.

Despite all the rage with the new wifi thermostats, I think the best solution is to just set them and forget them. You can put some set back and programming for times you know no one is home or a floor is unoccupied, but overall I'll never understand this new concept of constantly monitoring and adjusting room temperatures. I adjust for comfort. I have better things to do.
I have 8 thermostats-6 for heating (zones), 2 for AC. The AC's are programmable and adjust a couple degrees based on our usage.
The 6 heating (4 of them radiant), I haven't touched in years, except lowering the MBath floor 2 degrees on the shoulder seasons.

ratio

The Honeywell TH6110 is a cheap, reliable, programmable stat. Their big brother, the TH8321WF, has a WiFi model.

Don't go crazy with any setbacks, ±3° is plenty. Deeper than that the benefits are debatable and liabilities exist.

John Mills_5

The Focus Pro line is history though they may be kicking around in stores still. If you do want WiFi, the Emerson Sensi or the Honeywell Lyric TH6220WF2006 are rather affordable and nice units. The Lyric model is new, the Sensi has been out a few years and has proven very reliable. Now Alexa and Apple capable. You really want fancy, Ecobee4. Avoid Nest IMHO.