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Replacement Thermostat Question

I currently have a "newer" Honeywell round thermostat that I believe has issues. The switches are set properly. For example, with the room temperature showing about 66 degrees, I have to set the thermostat between 72-74 in order to turn on the boiler. If I try to reduce it to 70, as soon as it goes below the 72-74 range it kicks off. If I keep it at 72-74,it will run and maybe bring the system up to 68-70. If I set the temperature to 78 and it brings the system up to around 72.

In a replacement, I was going to see if a could find a new old stock Honeywell T86A (merc), or something similar to get better/more accurate performance. I had to search for a vintage style thermostat a few years ago at my old house to control my pellet stove as newer ones didn't seem to have a good enough "closure" to simulate a short circuit, allowing it to fire up.

Comments

  • Ironman
    Ironman Member Posts: 7,059
    Make and model of boiler? How many wires in the thermostat cable?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Jamie Hall
    Jamie Hall Member Posts: 20,401
    Is this a CT87? If so, having it level is critical. Is it?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mgambuzza
    mgambuzza Member Posts: 8
    Ironman said:

    Make and model of boiler? How many wires in the thermostat cable?

    Utica PEG300CDE, 2 wire.
  • mgambuzza
    mgambuzza Member Posts: 8

    Is this a CT87? If so, having it level is cri
    tical. Is it?

    Current one is a Honeywell T87K1007. Yes it is level, and set for Steam/Gravity.
  • Ironman
    Ironman Member Posts: 7,059
    That’s not a very reliable one. It’s a power stealing model that’s used when they’re only two wires available. You may have better results with a new one.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.