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Boiler Temp to High?

Dmelia1 Member Posts: 8
Hello all. Was looking for thoughts and advice on my boiler temp. While in the basement this morning before I work a took a quick peak at my unit and noticed the temp sitting at right around 210, PSI at just about 20 under no call for heat or circulation. No signs of pressure relief trip or any moisture under or around the boiler. With that, a call for heat came and the as the circ pump kicked in the pressure dropped down to 15psi and the unit ran through two cycles of heating switching the burners off at 180 each time which is what the aquastat is set to. By then the call for heat was met and circ pumped stopped. Unit is a Weil Mclain CGS-5. Is there a reason to be concerned here?


  • RayWohlfarth
    RayWohlfarth Member Posts: 1,371
    @Dmelia1 Cast iron boilers will continue to heat after the burner shuts off. The heat from the cast iron inside the boiler has to be dissipated. This will result in elevated water temperatures, especially if the circulator is off. Unlike a domestic water heater, the pressure relief valve is a pressure only relief valve. Typically these are set for 30 psi. You can verify that. The relief valve only opens when the pressure is above 30 psiIt sounds like the boiler is working properly if it shuts off at 180 I would be sure you have a company check it once a year.
    Ray Wohlfarth
    Boiler Lessons
  • Dmelia1
    Dmelia1 Member Posts: 8
    Ray, thanks for explanation!! We just had it serviced In February and the pro told us that it is in great shape. Appreciate you taking the time to help out!!
    EBEBRATT-Ed Member Posts: 14,572
    Agree with @RayWohlfarth

    Sounds like your fine