Ambient or Floor Sensing mode Benefits and Thermostat Recommendations

jimmydean

I am building a new home and we are close to being finished. I have a geothermal heat pump that feeds an in-floor hydronic heating system. Additionally there is a boiler backup that will kick on if the geo unit is unable to reach the desired set temperature. Basically if the geo unit runs for an hour straight, it will kick over to the boiler to reach the desired temperature as it can reach a higher temperature of the circulating water than the geo unit can do alone. The boiler is more sophisticated in how it calculates outlet temperature. The geo unit is just either on or off, the boiler looks at outside air temp, return line temp and figures out an appropriate supply line temp.

Currently during construction there are some very basic thermostats using ambient air temperature to control each zone, which works for the purpose of keeping it warm enough. But I wanted to start looking for my permanent thermostats.

So I started going down the rabbit hole of what thermostats I want to get to control this system. There are 5 zones to be controlled and each zone has an in-floor sensor available that was installed when we were building. I want something that is controllable via an app remotely, kind of like the ecobee I am used to at my current house. When I'm on vacation it's nice to be able to check and make sure it's still heating in the dead of winter. It's -10F outside today. One day without a functioning heat system is an emergency.

So with a system like this, what thermostat options would you recommend and also why would I use the in-floor sensor vs ambient with this setup? It seems like if you do in-floor sensing as the control, you need some way to figure out what the floor temp should be based on expected heat loss in the room to get the ambient temperature you want. Which will change based on what it's doing outside. 45F vs -10F, day or night, etc.. Seems like a lot of variables. So isn't controlling the ambient air the more direct way of controlling this system? I'm guessing the main drawback would be overshoot of your ambient setpoint. Or are there smart thermostats that do some math between ambient temp, in-floor temp and outside temp to better control the system? Just trying to figure out what options there are and what will control my ambient temperature more closely to what I'd like it to be.