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Gas boiler won't shut off - Slantfin S-90 DP

Multiman
Multiman Member Posts: 20
in Gas Heating

Gas fired for baseboard hot water Slantfin S-90 DP. No heat call. Replaced thermostat, worked fine, but then tenant said ran constantly, would not turn off. Replaced thermostat again, ran fine, turned off appropriately, and within hours, same problem, runs constantly, won't turn off. Any ideas?

Comments

  • 109A_5
    109A_5 Member Posts: 3,071
    edited October 31

    With the system actively not shutting off I would carefully disconnect one of the thermostats wires to see if it shuts off, prove it is or is not the thermostat. There could be a staple shorting the wires out and moving the thermostat to change it changes the symptoms briefly.

    Basically some electrical troubleshooting is needed. Do you have a multimeter ? Sometimes visual and mechanical inspection is all that is needed.

    image.png

    https://slantfin.com/wp-content/uploads/2015/11/Sentry-Installation-and-Operating-Instructions-119.pdf

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • mattmia2
    mattmia2 Member Posts: 14,623

    does it have zone valves?

  • Multiman
    Multiman Member Posts: 20

    I don't think so, because it doesn't do domestic hot water, and it's just a one loop baseboard hot water system for one floor.

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