oven pilot won't stay lit


  #1  
Old 08-06-05, 12:43 PM
kalocsa
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oven pilot won't stay lit

I have an old Tappan stove (1950). The burners work fine, but the oven pilot light won't light. I have the original manual. It says to hold in the red button on the safety valve while holding a match to the oven pilot and make sure the flame strikes the thermocouple tube. When I do this I get a nice blue flame that strikes the thermocouple, but as soon as I release the red button, it goes out. I'm not sure I understand the safety valve mechanism. It's supposed to stop the gas if the pilot light goes goes out, but what makes the pilot light stay on? The heat from the flame on the thermocouple? I've held in the button for over a minute, and it still goes out as soon as I release it. Is my safety valve defective? It was working when I got the stove, a few months ago, but it has been moved around a bit since then.
 
  #2  
Old 08-06-05, 04:32 PM
M
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The thermocouple produces electricity when heated. The "red button" you are depressing is an electro magnet safety. Either the t'couple has failed or the safety has high resistance or an open. If you are able to take millivolt reads do so and post reads. If you are unable, you may want to replace t'couple since it is the most common part to fail. Does the t'couple screw into the safety or 2 wire terminals?
 
  #3  
Old 08-06-05, 05:33 PM
kalocsa
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Wow, interesting physics. Maybe you can also explain how the "Oven On" light on the stove console is activated "directly by the burner flame" according to the manual.

The thermocouple loops around in a big coil and screws into the back of the safety. How do I take millivolt reads? With a regular voltage meter? Where do I take the reading?
 
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Old 08-06-05, 06:52 PM
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Oven On light? I can't explain at this time. Are you sure there are no wires and a switch off the thermostat. Yes a volt meter with a dc setting. Normally you would remove t'couple from safety, install an adapter, reinstall t'coupe into adapter, clip meter lead on t'couple itself and other lead on adapter. Now light pilot and watch meter. Normally in an operating system you would see a read of 12-16 m.v under load and that is the procedure I have outlined. IF the pilot stays on than blow out pilot and watch meter. When you hear the safety dropout or click as it closes record that read. A good safety will dropout at 2-3 mv. If the read is high around 20 or so than you have an open safety. In the absence of an adapter try an open read. This is done buy removing t'couple from safety, clipping one lead to t'couple and the other lead to the tip you have just removed from safety. Light pilot and check read. Now this is called an open read and is not a definitive way to test. You could have a read of say 24mv and have a t'couple that under load produces 0. So if you get a very low read you know t'couple is bad. WHEW sorry for length
 
  #5  
Old 08-08-05, 06:22 AM
kalocsa
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I think the 'oven on' light is part of a separate electrical system. There are wires going into the back of the thermostat.

I'm starting to understand how this works, and I think it's cool. What does an 'open safety' mean? Does it mean that gas could be leaking out?
 
  #6  
Old 08-08-05, 02:07 PM
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Open safety simply means there is an electrical open. Broken wire. No gas leak
 
  #7  
Old 09-27-05, 11:52 AM
kalocsa
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Yep. The safety was shot. I sent it away for a rebuild and a new thermocouple and the oven is working again. Here's to 50 more years of service...

Thanks.
 
 

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