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Triangle Tube Challenger won't switch to radiant unless I disable DHW

I have a Triangle Tube Challenger CC 105 that usually works great. However, there have been 3-4 times in the past month that I've come downstairs to discover the house cold. I go out to check on the unit, and see that my zone control unit is correctly calling for heat, but the Challenger display shows a normal (not error) status code of 6, "burner off due to reaching temperature setpoint." The temperature readout was ~115f, near where I have domestic hot water set since I have young kid. It seems like it's turned itself off due to reaching the domestic hot water setpoint and stops responding to calls for heat from the radiant system.

I can confirm this by setting the unit to radiant only, at which point it immediately and correctly responds to the call for heat. It seems like once it gets into this state, behavior is consistent no matter if the DHW setting is on timer/"smart", always on, or on-demand.

I'd like to have both hot water and warm floors again! Any thoughts?

Comments

  • Standyh
    Standyh Member Posts: 4
    Update: after the house got a bit warmer, I switched it back to dual domestic water/radiant mode, and it seems to be working normally again, for now. I'm just tired of getting surprised by this, and I know it's just a matter of time before it does it again.
  • Same thing happened to one of my customers about 3 weeks ago, but it was on a Triangle Tube Excellence. Ended up replacing the diverter valve.
    Often wrong, never in doubt.
  • kcopp
    kcopp Member Posts: 3,820
    The challenger has no 3 way valve...one of the neat things about it as a Combi. It does have a flow switch to get it to kick into hot water mode.
    I am wondering if some sand got into the flow switch and it is getting stuck open . What temp is the radiant set to run at?
  • Standyh
    Standyh Member Posts: 4
    Radiant is at the default of 186.
  • kcopp
    kcopp Member Posts: 3,820
    It may be a faulty sensor...
    186F is pretty high for a radiant floor.
    Do you have any pix of the set up?

    Standyh
  • Standyh
    Standyh Member Posts: 4
    Based on you mentioning that 186 is pretty high (it was the default), I lowered it to ~160 and the problem hasn't occurred since.  Maybe 186 is also a system maximum and it goes into some sort of lockout?  I don't know.  Anyway, just lowering the setting seems to have worked.