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Radiant and AC control in one smart thermostat

nancyl Member Posts: 20
Can you recommend a single smart thermostat that will control both hydronic radiant floor heat and AC control ?
Basic systems to control:
- 1stage heat (radiant pex in floor that has three different zones controlled by zone valves and a single boiler)
- 2 stage A/C (blower serving the same three zones via zone controls)
- HRV that will run year round
- eventually a steam humidifier added to the blower
- remote (smartphone) connectivity
- SmartHome integration (zwave or wifi) is a plus

I'm mostly trying to eliminate having three "dumb" thermostats to control the radiant plus three more thermostats to control just the A/C and year-round ventilation in favor of a single smart thermostat in each of the three zones.

I do have 5 lead wiring for the A/C and two lead wiring for the heat so something like the Tekmar 563 seems close to what I need. Am I right or are there better options?


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 6,175
    edited June 2022
    Just about any smart (WiFi) thermostat will do what you want. all you need is an isolation relay to operate the other equipment.

    In the AC air handler you wire up the system as usual then add a heat relay for the radiant system. wire the relay N/O contacts to the thermostat wires of the radiant system. Same for the HRV if you want the thermostat to operate that device on one of the heat or cool stages (or both).

    the Tekmar 563 looks perfect since there is an HRV option and also Humidity option built in (that other dumber SMART thermostats don't offer.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • hot_rod
    hot_rod Member Posts: 19,981
    look into the Ecobee also. A very user friendly smart stat.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream