Gas wall heater

Old 02-11-02, 04:28 PM
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Smile Gas wall heater

I have a wall heater that is mounted in the wall between two rooms. It is aprox 15 yrs. old? This wall heater was made by Williams Furnace Co. who's 800 number is no longer valid.
Orriginal prob was pilot light not staying lit so I changed thermocouple and it stayed lit. New problem--- after opperating heater for several minutes gas shuts off pilot light and all. I try relighting pilot and it will not stay lit. I noticed that directly under where I connected the thermocouples male end to the gas valve is a blue plastic piece with two wires coming out of it. I follow these wires to the top of heating unit and find them connected to something that looks like a snap disc or helix coil? This temp sensing device is located just outside an opening where room air goes in and mixes with hot gases before going up the pipe and out the roof. I am assuming that my vent pipe is clogged up and too much heat came out where it shouldn't have and this device sensed it and shut down the gas at the valve.
I removed the thermocouple from the valve and then removed this blue plastic piece and placed the thermocouple back on the valve and wala the pilot light stays lit. I put the blue piece with the two wires coming out of it back in place and reattach the thermocouple and the pilot light will not stay lit.
Question: What is that blue plastic piece with the two wires called? Does it act like a fuse, blow and need to be replaced? Where can I get one? Are my assumptions of a clogged pipe correct?
I appreciate your help with this

Old 02-11-02, 06:07 PM
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Hello Allan and Welcome to our Do It Yourself Web Site and my Gas Appliances forum.

The safety switch up near the downdraft diverter is there to do exactly what is happening, turn everything OFF if it senses too much heat being refelected back into the room.

You can disconnect the wires and check for continuity across it. If there isn't any, replace it. You may have a restricted flue vent or the vent cap on the roof is installed incorrectly.

The heat spillage at the diverter is activating the fuesable link and shuting off the heater. This may be the one time useable type and replacement is the only option. Clear the vent first. Roofers often reset the vent caps on to far down on the pipe, so if the house has been reroofed, check the cap.

Another possibility could be the magneto which is the part that the thermocouple screws into. If it's defective, it will internally shortout and shut the unit off.

Another possibility is a dirty pilot flame. The pilot flame must not have any yellow tips or any yellow flame period. If there are yellow flames, clean the entire assembly. All the tiny holes in it but be carefull not to lose the pilot orifice.

The thermocouple may be New and or not very old but that's no guarantee it's good. Try another one.

An excellent source for orginal replacement parts is your local retail appliance parts store. Appliance parts dealers test and carry replacement parts for all appliances. Parts dealers are listed in the phone book under appliances.

Retail parts dealers can also help determine what the possible problem may be. Bring the make, model and serial numbers if you stop in at the store. The info will help to determine the exact parts used in the model assembly line run and possible problem causes.

Check the RECENT topics and ARCHIVES, within this forum, for other postings on this topic and the replies offered.

Regards & Good Luck
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