Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Iron Fireman Thermostat Question

I recently acquired an Iron Fireman Thermostat model T-114. Yeah, I collect things like this. But on this one, it is 2 wire (as you can see in photo). But it doesn't seem like the connection on the left connects to anything making me wonder how this worked? I also noticed the coil of wire around the bar and wondered if anyone knows what that was for?

Really appreciate any information on this unit. I have never seen one like it and nothing on the internet to help either. That was surprising because Iron Fireman was a big company at one time.


  • ratio
    ratio Member Posts: 3,185
    Without having it in my hand, I'd say that the frame, or some part of it, is connected to the terminal that doesn't connect to anything, and the coil of wire is going to be the anticipator, it connects in parallel with the contacts, right?
    JUGHNE Member Posts: 9,765
    Could you adjust the heat anticipator coil, (if that is what it is) by sliding the coil up and down on that bar. That would affect the movement of the long bi-metallic strip perhaps?
  • Jamie Hall
    Jamie Hall Member Posts: 18,962
    So simple. I love gadgets like that. And most likely both @ratio and @JUGHNE are right.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • CKNJ
    CKNJ Member Posts: 49
    JUGHNE:. That wrap of wire is stationary. The ends are under the screws at each end. But I do believe it is an anticipator of some type.

    I guess what I am trying to understand is how does it complete the circuit? I also haven't figured out what the 2 screws on the bottom right do.

    To be honest, mostly I have seen the old Minneapolis Honeywell type so this really intrigued me. MH usually have a small wire that connects the arm to the ground terminal.
  • ratio
    ratio Member Posts: 3,185
    Maybe it's provisions for a function that this model doesn't have. Look at the arm towards the contacts. Does it have one, or a mark like one could go there, on the back side of it. Like for cooling maybe?
  • CKNJ
    CKNJ Member Posts: 49
    Just as a follow up for anyone interested. Yes, the thermostat grounds through the body. When heat is satisfied, the arm breaks contact with the adjustment screw on the left side (which is also adjustable for temperature swing) and then makes contact with the block where the two screws (lower right) are. Those 2 screws would have been connected to the Iron Fireman controls in the basement that would have kept the fire on stand by until the next call for heat.

    Yeah, I am a geek.