[xisbrat]

Although my question sounds similar to other topics, this is very different. I think a gas valve component is getting abnormally hot!

My furnace will turn on, the gas burners will light, and blower will turn on for about 5-10 minutes, enough to move the temp up 2 or 3 degress. Then the furnace shuts off, well before the desired thermostat temp is reached. In order to get the furnace to turn on again, I must turn off the furnace (using off/heat/cool switch on thermostat), wait about 20-30 minutes, then turn the furnace back on.

I touched a part of the gas valve one time, and I was alarmed that one of the components of the gas valve was extremely hot. It is a Trane 2622 gas valve, that has an electronic control unit with 5 contacts. The piece that gets extremely hot is the top part of a metal housing surrounding a tall black cylinder (there are two black cylinders on the valve, this is the taller one, about 2 in high, standing on its end). I think this housing is a heat sink. By hot, I mean you cannot hold your finger to it for more than 5 seconds. Only one piece at the top of this heat sink gets hot. The black walls of the cylinder itself, or the metal walls of the heat sink that surround the cylinder, is not hot. The only part that gets hot is (what looks like) a button that protrudes through the top of the heat sink. From some readings, it is my belief that this cylinder is a solenoid, and for some reason the solenoid is reaching alarming temperatures.

Because it was so hot, I started the shut off/turn on sequence for the furnace (via the thermostat). After 20-30 minutes, the solenoid is cool again, and then the whole cycle starts all over. My thinking is that the solenoid is failing, gets too hot, and a safety mechanism turns off the burners. When the solenoid cools off, the gas burners will turn on again.

By the way, the pilot flame is on most of the day. Since this is an electronic (automotic) pilot, I believe the thermostat is working OK, as it has ignited the pilot. But the burners don't light, and I think that is because of the overheating solenoid.

I have a Trane furnace, originally built in 1987, part no BLU05L924A2, puts out 45 btu/hr. The Trane gas valve was replaced in 1997. Is this a sign of a failing gas valve. Is it common for gas valves to fail every 10 years? Maybe this Trane valve has a bad history?

Your advice/comment will be greatly appreciated.

[hvac1000]

That item you are talking about is a solenoid coil and you have to replace the valve if it proves defective.

The pilot is not to stay on all the time. It is supposed to lite just before the main flame of the furnace kicks in.

If the valve is of a White Rodgers manufacturing the problem is the valve. White Rodgers did have a problem exactly like what you are stating back in 1986 to 1988. Trane does not make there own gas valves.

You might want to get a professional opinion on site before you replace. A bad ground or loose connections can sometimes cause problems.