No announcement yet.

help with low voltage heating thermostat


Forum Top GA Ad Widget

  • Filter
  • Time
  • Show
Clear All
new posts

  • help with low voltage heating thermostat

    I'm trying to remove a programed thermostat to a regular.But, this is an old house the wires are red and black. So where does the live wire go ? Is the live wire red?Does it go on the mercury screw or not?Also is it easy to move the location of the box? Can there be 2 thermostats, on seperate floors?? Should the power be off? Well anyone that can answer these questions would be greatly appreciated Thank-you

  • #2
    The Honeywell and Robert-Shaw two wire thermostats will work. Honeywell is a mercury bulb style and Robert/shaw is a bi-metal.
    The low voltage is 24 volt. One wire is hot one is the return to the TH terminal on the burner control.
    If you parallel connect two thermostats - one will take priority over the other - the one adjusted at the higher temperature will control the burner.
    However if the stat is controlling a zoned hot water system then it will open n close its own zoning valve and the valve will control the burner.


    • #3
      Usually the 2 wires you need are: Red and White (R & W terminals). This is the normal wiring, but you should check at the furnace. Usually one wire goes to the transformer and the other to the gas valve on older furnaces. Newer models usually have a terminal stip with easy to see markings.

      ~Do it Right or Not at All~


      • #4
        Almost any new thermostat will have terminals with letter designations. If you just have two wires, they would almost always go Red to R and W to white. The new thermostat will have installation diagrams which will be very clear on what to do.