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1 zone wont run properly. Please help

cahner Member Posts: 2
I have an infloor radiant system that has never been problematic.

When the zone in question asks for heat we get only the yellow light on the zone control at the boiler unless another zone is running and it will then light the red light on the bottom. It will not light the boiler independently.

This is a 5 zone system. There is 1 zone made up of 2 loops that has quit working. The first thing I did was change thermostats, that did not help. I then moved the wiring to a spare on the control board at the boiler. This changed nothing as well. I then isolated the 2 telestats and left only 1 connected, no change again.

The telestats open and close as they should and plungers move freely. Power is sent to the control board so I do not believe it is wiring. At the control panel with a zone running I get a reading of 0 volts on the telestat part of the board for the 4 properly functioning zone. I get a reading of 6 to 7 volts on the problem zone. This leads me to believe the problem is in the telestat, particularly the end switch.

Any suggestions or ideas please.



  • Zman
    Zman Member Posts: 7,001
    It does sound like an end switch problem.
    If you switch the telestat heads, does the problem go with it?
    There is also a limit to how many telestats you can put on one zone, it could be that there is not enough power to fully open them both at the same time.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • cahner
    cahner Member Posts: 2
    They have been running together for 13 years and run together now fine. I have isolated the two problems but have not switched one with one from another zone. That will be next.

    I have two new ones but dont want to use them unless necessary.

    Thank you for the suggestion. I appreciate it.

  • rick in Alaska
    rick in Alaska Member Posts: 1,243
    Trying a new telestat will definitely be your best bet. Could be you have two bad telestat end switches, or maybe a broken wire somewhere, but if you put on new telestat and it works, then that will answer the question.