How to connect a digital honeywell thermostat to an old thermostat system?

when i open my old thermostat there are 2 wires coming out, red and black. in the honeywell system it gives me options for the red wire to be put in, but where does the black wire go ??How to connect a digital honeywell thermostat to an old thermostat system?If your heating system is a wall furnace with one red and one black wire, you will need a thermostat that is compatible with millivolts. A gas furnace using a pilot light has a thermocouple which produces millivolts of electricity from the heat of the pilot light flame.



If the thermostat happens to be compatible with millivolts, connect black wire where the W wire would go and then the red wire to R .



Good luck,



Cool#9How to connect a digital honeywell thermostat to an old thermostat system?Apparently that old stat only controls just a heater or furnace of some sort, so you should then only need the use of the W1 and Rh connections on the new thermostat. I can only assume that the red wire from the old stat is the transformer wire and the black wire is the one that should go to W1. So that work for ya even if its the other way. Then make sure that the electric or gas switch is set to gas. Im assuming its gas.