Posts Tagged ‘ Wire ’

I’d like to know if I can replace my 2 wire non digital (hot water baseboard heat, oil fired) thermostat with a 7 day programmable thermostat from Honeywell. I’ve tried looking at the www.yourhome.honeywell.com site but they don’t actually show you how many wires are on the back of the unit I want to install (RTH8500D). I want to buy the item from ebay because I can save myself about half the cost, but I also cannot return it if I buy the wrong thing. Anyone have any suggestions?

I have red green blue and white wires. I followed instructions in manual and heat works but a/c doesn’t. I used programmable during the winter but had to reinstall my old thermostat for summer. Connections on new thermostat are G, Rc, Rh, Y/O, W/B, Y1. There is a jumper preinstalled from Rc to Rh. Thanks.

Have moved into a house where previous owner replaced simple mechanical type thermostat (with mercury bulb) with an electronic unit. Mechanical type obviously just closes a contact to complete the gas valve circuit and so get 24V across gas valve coil.
Obviously 2 wire electronic unit cannot do this because the unit needs to draw power for the electronics.
The new thermostat is giving unreliable operation, am thinking of replacing it with the old unit which I found and appears to be functional (checked with multimeter).