Smart thermostat for separate AC and RADIATOR HEAT.

Chris_Eaton

I'd like to use a smart thermostat to control our radiator heater system and or AC system. Our current thermostat requires switching to AC or Heat and then setting the desired temperature. Is there a Smart solution? We have a small one zone home that heats or cools as needed. I'd like to add a smart thermostat to just set temperature and let the thermostat call heat or cold. What ever is needed. Thanks I advance for your help.

Jamie Hall

I believe the Ecobees will automatically switch…

EdTheHeaterMan

It sounds like you have one thermostat that is connected to two different systems. If that is the case, then you can use just about any smart thermostat for that setup. The key is to understand how your current thermostat is connected to the two different systems. Usually there are two R wire connections for that set up. The R for heat may have Rh and the R for the cooling may be labeled Rc. You may have a thermostat with R and Rh, or you may have a thermostat with Rc and Rh. There may even be a thermostat that is labeled Rc and R but that is unlikely.

You just need to know that the smart thermostat the requires a C wire connection usually needs to be connected to the R for the cooling system and the C from that transformer for the cooling system. The cooling system transformer MUST be powered all year. So if you shut off the circuit breaker for the air conditioner in the winter, that transformer will no longer power the thermostat and it will not work in the winter time. You must leave the cooling system powered and set the thermostat to heat so the air conditioner will not operate.

The heating system will then be able to use the Rh and the W from the smart thermostat to operate the heating system. You may be able to then select heat in the winter and cool in the summer just like you do with your present thermostat. there is even a function in the smart thermmostat App, the will allow a setting of AUTO for the Heat/Cool function where you set the cooling temperature at something like 74° and the heating teperature to something like 68° and just let the system select heating or cooling as needed based on the outdoor weather and the needs of your home.

There is one drawback from setting the thermostat to AUTO Heat/Cool. If you have a particularly warm winter day and you use the fire place for ambiance with a large number of guests, the room temperature where the thermostat is located may go above 75° while you are entertaining guests. That will then set the air conditioner to operate while the outdoor is mild for that time of year but still too cold for safe operation of the compressor, and you could damage your air conditioner without knowing it. This is unlikely but it has been known to happen.

HVACNUT

A lot of Resideo smart thermostats offer auto changeover. T6 Pro. T9. T10. To name a few.