Question about Heating & Cooling
What type of gas supply line do you have? Is it black pipe or copper? If it is copper, there can be a film like substance that builds up on the inside of the copper. The debris will the get caught in a pre screen where the supply enters the valve thus cutting the supply of gas to the unit. Also, the thermocouple may be bad. You didn't say that you replaced it. Try replacing it as well. Also, you could have a limit switch turning the system off and thus cutting the gas off completely but it is highly unusual for the pilot to be cut off as well unless the pilot is being blown out when the gas is shut off. Also, turn the unit to fan only without calling for heat. Using a flame of some sort, put it into each baffle of the heat exchanger. If your flame is being blown around in one of the baffles, then you have a hole in the heat exchanger and what is happening is that the roll out switch is cutting the unit off and the air still moving through the heat exchanger is blowing the pilot out. I have seen this actually happen. If your furnace is in excess of 15 years old, it does need to be checked for possible holes. If it is in excess of 25 years old, it is a huge possibility that the unit has already developed a hole. If you feel hair coming out of one of the baffles, then shut the unit down immediately and have it replaced!
Posted on Apr 05, 2009
It sounds like your main valve. The diaphram may be loose fitting or it has a small leak.
Posted on Oct 03, 2009
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Probably a bad solenoid in the gas valve. Higher voltage of a new thermocouple keeps it open longer but it still fails over a period of time. Look into a new gas valve for the water heater.
Posted on Dec 17, 2009
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