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HBX THM-0100

Looking for people that have experience with the HBX THM-0100 Non programmable thermostat.

I switched to this thermostat this winter because it has a floor sensor and dual mode. It is being used to control the in floor heat for my shop. I also have wood heat in the shop that I occasionally use. Therefore I wanted the floor sensor so the floor wouldn't cool off to much during the days I use the wood heat.

While operating the thermostat in dual mode I noticed some weird things. In the settings you can set the Min and Max floor temps, which will override the air temp control when needed. The one day I was using the wood heat, so the air temp was way over setpoint. The floor temp dropped and the boiler kicked in as it should. But then the floor temp reached my Min setpoint and the boiler just kept running and running until I was a degree over the setpoint already. I finally just turned it off to save on propane.

Is this normal for this thermostat? Does it have something to do with meeting in the middle of the Min and Max floor setpoints? I don't know how the algorithm is setup to operate. Possibly a tighter Min/Max range is needed. Let me know, any information is helpful.


    HVACNUT Member Posts: 5,841
    The floor should've already been at the minimum temperature. To override the maximum temperature could be a sensor error. Is it a 10K sensor? Can you ohm it out?
  • Chevra
    Chevra Member Posts: 11
    Not sure what you mean by it should've already been at minimum temp?

    When this happened I hadn't run the in floor heat in a couple days because I was using wood heat at that time. My Min temp was set at 15C, the floor eventually dropped to 14C and the boiler kicked in. It just wasn't kicking out when I expected it to. My Max temp was set at 18C I believe. Am I thinking about this backwards or something?

    I could test the sensor yes, but the readings seem believable to me and it is brand new as well.
  • hot_rod
    hot_rod Member Posts: 22,157
    Is the min the turn on temperature for the floor, and the max the temperature it will shut off at. If so it was trying to reach floor max.

    What are the min/ max settings.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Chevra
    Chevra Member Posts: 11
    hot_rod said:

    Is the min the turn on temperature for the floor, and the max the temperature it will shut off at. If so it was trying to reach floor max.

    This is exactly what I am wondering. I don't think that is the case but the manual doesn't really explain it well either. It really only states that when running in DUAL mode it will run off the AIR setpoint first. It will override the AIR setpoint if FLOOR temp drops below MIN setpoint or if FLOOR temp hits the MAX setpoint. This leads me to believe it should not run the boiler from MIN all the way to MAX setpoint. I sent an email to HBX but did not get a reply yet. I will experiment with it more when I have time. Just thought that someone might have some experience with it is all.

    Current setpoints while in DUAL mode:
    AIR setpoint: 15C
    MIN floor setpoint: 15C
    MAX floor setpoint: 18C