Gas valve problems...


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Old 03-02-03, 10:52 AM
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Question Gas valve problems...

Hello everyone. This is my first post here and I'm hoping you can help me out. I live in Alberta, Canada where the winters can get downright cold. Our furnace is acting up, let me explain the problem.

Firstly, this is a older Lennox furnace Model No. GH6-100T (1961, I believe) with a General Contorols gas valve. The valve and what I believe to be the controler attached to it have several numbers on it. Just let me know what reference numbers you need and I'll gladly provide them.

Most of the time, it operates properly. But lately, and more often all the time, the old girl won't ignite. The pilot is going all the time like it should, but I think the gas valve isn't opening to ignite the burners. There's a reset button on the valve, and when I press it, the furnace ignites as it should. Sometimes it will work properly for the rest of the day, but sometimes I have to press that reset button 3 or 4 times a day.

Right beside the reset button is a hardline going to a fixture right beside the pilot light, actually in the small flame. What's that lttle fixture called, a thermocouple? And could you give me a brief overview of how the gas valve and it's controls work? I'm sure that if I better knew the sequence of events, that I could troubleshoot this alot easier.

Thanks for your help,

Mike
 
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Old 03-02-03, 11:46 AM
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I found some information at http://www.achrnews.com/CDA/ArticleI...,12454,00.html that explained alot for me. The thermocouple has a gray sooty-looking material on it where the pilot flame hits it. I'm going to clean it up and see if that helps. I think it could be that the thermocouple isn't getting enough heat to keep the signal constant to the valve. Please let me know if you think I'm on the right track here.

Thanks again,
Mike
 
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Old 03-02-03, 01:50 PM
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mike,

if the pilot flame is staying lit, rule out the thermocouple. what is that red reset button? can you find info on it on the furnace label? whatever that resets (possibly flame rollout) is the problem. clean the burners if possible with a shop vac if needed.
 
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Old 03-02-03, 07:10 PM
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On the label it says;
1. Open Pilot Valve and Light Pilot.
2. Push Manual Reset Button after Pilot has been lighted for about one minute.
3. Open Main Valve.
4. Set Room Thermostat Indicator to desired temperature.

That's the only reference I can see to a button. I cleaned up what I believe to be the thermocouple this afternoon and it has worked good since. Got my fingers crossed. There are two things near the pilot flame. The one is right in the flame, the thermocouple I think. But what is the other one? It sits about an inch or so from the flame. I wish I had a digital cam so I could show you exactly what I mean.

Mike
 
 

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