Original message
| jasonM
 |  "Ignitor turns off early + gas doesn't light"
, posted Sun 13 Jun 20:42  
Hi,
I have Rheem Model 10EQAGS residential gas furnace, circa 1989.
It stopped blowing warm air 2 weeks ago, so I opened up the thing and cycled power. Fans come on (both) as appropriate, but no ignitor so I pulled it out. Sure enough, it was burned through visibly, so I ordered a replacement.
In installing the replacement I managed to pull a hey stupid and short the thing to ground, testing my circuit breaker. It works. I mounted the thing correctly, then reset breaker and re tested. I set the thermostat setpoint to 78 deg, current inside temp is 71 (per thermostat). I powered on the furnace.
The main blower starts, the ignitor heats up (and doesn't short), and the gas starts flowing. 2 seconds after the gas starts, the ignitor powers down. The gas does not ignite.
Just to test the burners, I hit it briefly with a plumbers soldering torch as an ignition source,and the burners will light. The flame looks nice and blue and relatively uniform on all burners. The furnace appeared to run OK this way, but it will still not start with the ignitor the correct way.
Any suggestions.
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Replies:
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| xenos
Webmaster 
|  "Re(1):Ignitor turns off early + gas doesn't l"
, posted Sun 13 Jun 20:56
Either the ignitor is installed incorectly or something is bent and not allowing the gas to touch it. It's also possbile for the gas pressure not be at 3.5" however logic would state it just happened.
Xenos.
The best way to escape a problem is to solve it.
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| | jasonm
| "Re(2):Ignitor turns off early + gas doesn't l" , posted Mon 14 Jun 00:28
It seems that the ignitor doesn't stay on very long though. It really is only on for 3 seconds max, while the gas is flowing.
Will the gas light normally if the ignitor is cooling off and it is already a dull red color, not bright at all?
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| | xenos
Webmaster
| "Re(3):Ignitor turns off early + gas doesn't l" , posted Mon 14 Jun 17:26
No, is the pressure switch opening?
Xenos.
The best way to escape a problem is to solve it.
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| | jasonM
| "Re(4):Ignitor turns off early + gas doesn't l" , posted Mon 14 Jun 18:33
I'll check with a voltmeter tonight. I assume this is 24VDC logic ?
I can't see why the pressure switch would all of a sudden be popping off if the blower has been running for at least 30 seconds before it even tries to fire the ignitor.
Sorry for the trouble. It is such an old clunker furnace, that I had intended to replace it late this summer anyway.
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