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Replacing White-Rodgers 1e30-910

kate_gkate_g Member Posts: 1
I inherited a very old mercury thermostat with my condo, and I'm trying to replace it with a basic programmable model. It's a heat-only system. I have 2 wires–a red wire connected to the R5 terminal and a white one connected to the 4 terminal. My best guess is that R5 -> R and 4 -> W but I can't find anything definitive. Is there any way to confirm this without tracking wires down to the boiler (I am not able to do this)?


  • Jamie HallJamie Hall Member Posts: 14,797
    That will work. I'm a bit puzzled, though, as the thermostat you mention -- the White-Rodgers 1e30-910 is not programmable, and will not do anything the old mercury thermostat (which, by the way, is far more reliable, accurate, and precise -- much better thermostat than the White-Rodgers). Is that the model you meant?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • JUGHNEJUGHNE Member Posts: 7,861
    The WR 1E30-910 is your old tstat? yes.
    If so the 2 wires are the R & W you are looking for.

    Be sure to get a new one with batteries. Or you lose the programing and screen in power blink. The Nest, for a boiler, is probably not recommended by anyone here.
    I would go with HoneyWell Focuspro series. I think it is the 6000 series.
    Large numbers, gives both actual temp in room and your desired setting.
    Go to for selection.

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