I recently purchased a new Honeywell CT87K Thermostat for a gas heat furnace. The temp on the thermostat never goes below 72 degrees. I used an ordinary room thermometer and the temperature was reading 55 degrees, but the stat read 72. I had to turn the stat up to 80 degrees just to get the furnace to turn on. Then after a short while, the room became very hot. I read the manual and I took the casing off the stat, but I can not figure out what I am doing wrong. I even called Honeywell, but they had no interest in helping me. I still have the receipt, but I do not have the package, so the store won't let me return it. I am about to just go out and buy a new stat, but I wanted to make sure that there wasn't anything else that I could try first. I did jump start the wires and the furnace appears to work just fine. Any help is appreciated. Thank you.

Honeywell ct87k round themostat I have 3 zone hot water boiler installed the guy put three ct87k stats in and the heat never goes pasted 72, I jumped the wires and it went up to 82 do you have any suggestions thanks tommy