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thermostat control

philgphilg Posts: 4Member
I have a gas fed boiler with a separate hot water heater. Recently installed a Honeywell

thermostat CT87K and at times it seems that it does not recognize the room temp and the

boiler keeps running. While this is happening the pressure guage shows a reading of 10, is this normal?

Is this thermostat known to have this type of problem?

Any suggestions for a better thermostat?



  • IronmanIronman Posts: 5,093Member
    Did You..

    Set the CPH for a hot water system? It should be 3 per hour for finned tube baseboard or 1 per hour if your system was ever a gravity flow. You use the dip switches on the back of the stat.

    And no, that's not by any means the most accurate stat that Honeywell makes.

    10psi is too low with a hot boiler. Should be 12psi cold on a two story house; 18psi cold on a three story. Your fill valve needs to be checked.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • will smith_4will smith_4 Posts: 259Member
    t-stat control

    How do you know your stat doesn't recognize space temp? The reason I ask that is that some systems have a stat that only controls a pump, and as long as power is supplied to the boiler, the boiler might cycle based on low and high limit settings. What other controls do you have in the circuit other than the t-stat?

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