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American standard arcoliner

jonatale Member Posts: 1
I have two apartments an upstairs and a downstairs two thermostats one furnace when the thermostat is shut off on the first floor I am still getting Heat on the first floor when the second floor is turned on


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,157
    edited December 2022
    @jonatale, there could be several reasons.
    What are the thermostats connected to? Zone valves?. circulator relays? Duct dampers? other?

    Are both thermostats connected top the same control? as in 2 wires under the same screw terminal?

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • mattmia2
    mattmia2 Member Posts: 9,850
    I assume this is set up as hot water? Pictures of the boiler and near boiler piping wherever the zone controls are.
  • bburd
    bburd Member Posts: 926
    edited December 2022
    The most likely possibility is an open or failed flow check valve on the first floor zone supply. This is a weighted check valve that is supposed to prevent circulation unless that zone is calling for heat. Sometimes they have a lever that allows them to be placed in manually open mode. Check this. 

    The next most likely cause is that the first floor zone valve (if any) is failed open, or someone has opened its manual lever.

    Beyond that, you get into things like wiring problems.