Hey Guys!

I'm new here! I hope all is well :)!

I live in Jersey City, NJ and our heating system is relatively old. We have a gas furnace and we have radiators with a steam system. Our old thermostat was a Honeywell mercury thermostat. We are remodeling the upstairs and the contractor inadvertently broke the old thermostat and did not wire up our new Honeywell CT87A thermostat properly (or so I believe).

We have a total of 4 wires in the main wire that's insulated that comes up through the floor. The green wire was coiled around and I ASSUME was never used. The wires that are currently connected are the RED, WHITE, and BLUE. We have Series 20 Wiring (this is what it said on the back plate of the old thermostat).

On the old thermostat it stated to put the Red to R, the Blue to W, and the White to Y. We did this and the heat turns on but never turns off. If I jump the red and white wire the heat does turn on without any problem.

What can I do to wire this so that the heat turns off when the thermostat is turned off? I really would like to do this myself and not pay an electrician or heating tech. The old thermostat was working just fine but the contractor does not remember the wiring and I'm sort of at a loss here. My only solution to turn off the heat is to turn it off from the main breaker switch or remove the thermostat.

I anticipate your help and am anxious to get this up and running! Thanks again guys!

If you do not have an air conditioner connected to the thermostat then I think you only need to use two of the wires, one that takes the power to the thermostat and the second to carry the power back to the terminal that turns on the heat.

You can check to see where the other wire goes to.

First I would disconnect the wires from the thermostat. I would then touch the red wire to the white wire and see if the heat comes on. Then move the red wire from the white wire and see if the heat goes off.

Do the same with the red and the blue wire. Which ever one make the heat operate properly connected to the red is the wire to use on the
W terminal.

If you do not have an air conditioner connected to the thermostat then I think you only need to use two of the wires, one that takes the power to the thermostat and the second to carry the power back to the terminal that turns on the heat.

You can check to see where the other wire goes to.

First I would disconnect the wires from the thermostat. I would then touch the red wire to the white wire and see if the heat comes on. Then move the red wire from the white wire and see if the heat goes off.

Do the same with the red and the blue wire. Which ever one make the heat operate properly connected to the red is the wire to use on the
W terminal.

Thanks for your reply mate! On the old wall plate for the old thermostat the wiring diagram showed that the white wire went to the Y. Should I still try this on the Y or hook it up to the W?

When I touch the red and white wires heat does come on. It does not come on when I touch the red and blue.

What does happen when you touch red to blue. If you don't have AC it probaply does not do anythiing.

What does happen when you touch red to blue. If you don't have AC it probaply does not do anythiing.

Hey! Connecting the Red and Blue does absolutely nothing. I do not have any sort of A/C. I connected the Red wire to the "R" and white to the "W" the heat does turn on with the thermostat on. Maybe I should wait a while and see if it totally turns off? Would having the blue wire connected prevent the thermostat from turning off the heat?