[marc]

I have a carrier central natural gas heater model 28rds030000 we have heat, but it won't shut off, I replaced the thermostat and it still does the same thing. Can anyone help me locate this problem?

Marc (DELAWARE)

[labman]

I copied this from an answer I gave yesterday to a similar problem.

You do have a furnace, not a heat pump? It is fairly common for the blower relay to stick, but it would a real coincidence for the heat valve to stick too. I am guess it is the thermostat, cheap and simple to replace. First, try switching it to cool. If that doesn't work, shut the power off and remove it from the wall. Remove the red and white wires noting if they come off terminals marked R and W. With them not touching, turn the power back on. If the heat doesn't come on, the problem is in the thermostat. Note, the burner will come on until the furnace heats up and the blower, which also runs a little after the burner goes off. If the heat comes on, go to the furnace and disconnect the white or red wire. If that fixes the problem, it is the wiring between the furnace and thermostat. If that still doesn't stop the heat from coming on, likely the control board is bad. Harder and more expensive, but still can be a DIY project.

Check the things I suggested, and post back if you need more help correcting the problem once you identified it.

[marc]

I copied this from an answer I gave yesterday to a similar problem.

You do have a furnace, not a heat pump? It is fairly common for the blower relay to stick, but it would a real coincidence for the heat valve to stick too. I am guess it is the thermostat, cheap and simple to replace. First, try switching it to cool. If that doesn't work, shut the power off and remove it from the wall. Remove the red and white wires noting if they come off terminals marked R and W. With them not touching, turn the power back on. If the heat doesn't come on, the problem is in the thermostat. Note, the burner will come on until the furnace heats up and the the blower, which also runs a little after the burner goes off. If the heat comes on, go to the furnace and disconnect the white or red wire. If that fixes the problem, it is the wiring between the furnace and thermostat. If that still doesn't stop the heat from coming on, likely the control board is bad. Harder and more expensive, but still can be a DIY project.

Check the things I suggested, and post back if you need more help correcting the problem once you identified it.

Do I touch the white and red wire together or just leave them alone when I disconnect them?

[labman]

Maybe the best thing to do is to disconnect the white wire at the furnace. If the gas cuts off, the blower shouldn't right away, the problem is in the thermostat or the wiring. If it keeps going, the problem is inside the furnace, likely on the control board. The boards make problems less likely, but difficult for DIY trouble shooting.

[marc]

Does anyone know the cheapest place to get a control board for a carrier gas heater?

Marc
(Delaware)