I remodled my kitchen and installed a new thermostat. After Installing the new thermostat the furnace will not turn off. If I set the Thermostat to 70, the temp will surpass that and almost hit 90 degrees. The only way to turn off the heat is to physically go to the furnace and push the button on the top from manual to automatic. That will turn it off and just leave the pilot light on. Some more information. The Gas furnace is 20+ yrs old, but heats great. I have hot water radiators. Even If I pull the face plate off the thermostat the heat stays on. It says millivolt on the furnace so is that 12v or 24v? Any help would be appreciated
2006-10-17 17:39:21 · 10 answers · asked by sheltz32tt 2 in Home & Garden ➔ Maintenance & Repairs
A repairman from my utility company once told me that there were two types of thermostats for natural gas heaters. He told me to get the one called "millivolt" instead of "24 volt". He said the 24 volt thermostat would not work for my furnace. Millivolt means just what it says - very low voltage. The thermostat uses the heat from the furnace to power it. In other words, it doesn't need AC. A 24 volt thermostat needs an AC connection.
I'm not positive about that, but I think the general message is pretty much right.
The Home Depot should sell both types of thermostats, and they should clearly say either millivolt or 24 volt.
2006-10-17 18:44:52 · answer #1 · answered by ? 6 · 1⤊ 0⤋
You stated that you have hot water radiators. You must have a 'boiler', not a standard gas forced air furnace. Either the thermosttat is wired improperly or you have the wrong type of thermostat.
Personally I would call a well known furnace shop in your area and explain the situation to them. You might need a "service call' to correctly identify the problem and fix it. They should also check the furnace for proper operation, carbon monoxide leaks and overall safety. A 20+ year old boiler should operate for many more years. A standard 20+ year old GAS FURNACE most likely has seen its best days and is no longer efficient. Inefficient furnaces and boilers will cost you unnecessary money in fuel bills.
2006-10-17 17:53:58 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Along with these other answers, you will want to check to see if your thermostat has a battery. If it does, replace it. If your thermostat is one with a timer it most likely will and if the battery is not good it will not stop the furnace from running. Been there. Done that.
2006-10-19 15:59:57 · answer #3 · answered by Braveheart 3 · 0⤊ 0⤋
Millivolt is 750 millivolts. a 24 volt thermostat won't work on it. If it is 24 v you have a short in the wiring.
2006-10-18 01:45:44 · answer #4 · answered by bob r 4 · 0⤊ 0⤋
Only a few things could be going on here I would first check my T-stat wiring it may be incorrect if that is correct make sure you installed the correct T-stat. If all that is correct your cheapest out with the least amount of headache would be to call Heating contractor you may have a serious problem..
2006-10-18 13:26:22 · answer #5 · answered by Anonymous · 0⤊ 0⤋
You may have installed the heat wires to the air condition terminals.
That would make it look for a lower temp to shut off the current ...
2006-10-17 17:45:07 · answer #6 · answered by Anonymous · 0⤊ 0⤋
24 volt.sounds like you have the wires making contact.if it shuts off evenually it may be that the anticipater on the thermostat is not set correctly
2006-10-17 17:50:19 · answer #7 · answered by bill b 5 · 0⤊ 0⤋
Your thermostat wires are backwards. If it was the wrong voltage for the stat it would not work at all.
2006-10-18 01:31:50 · answer #8 · answered by tpjp19 2 · 0⤊ 0⤋
ok you KNOW the Tstat is the problem, since this happened only after YOU changed it. Also YOU know you bought the wrong Tstat since your furnace says millivolt and you bought something else...
2006-10-18 02:21:21 · answer #9 · answered by Anonymous · 0⤊ 1⤋
Check your thermostat wiring..
2006-10-17 17:50:50 · answer #10 · answered by MeInUSA 5 · 0⤊ 0⤋