Pilot on but no igntion


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Old 03-31-08, 08:02 AM
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Pilot on but no igntion

Hello all and thanks in advance for whatever advice you can offer.

I have a Rheem Furnace RGDA 10EC-EA that came with the house when I got it. It's equipped with HSI using a Honeywell S89G controller.

Here's the intermittent problem. Thermostat calls for heat and the igniter glows nice and hot. Typically, I hear the gas valve click on and the pilot bar gets lit, and the furnace fires up. But, every now and then (once a week more or less) I walk into a cold house or wake up in one.

The igniter will glow but the furnace wonít fire up. My fix is to shut the furnace breaker off, and thermostat. Let sit for 30-45 minutes and turn everything back on. I first thought maybe the pilot rail was dirty and I cleaned it. Iíve checked all the connections and they all seem fine. Any thoughts on a bad control unit or something else?
 
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Old 03-31-08, 07:27 PM
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Mkae sure the flame sensor is clean (use steel wool) and that the pilot flame strikes it squarely. If that doesn't help, I would suspect the S89.

Ken
 
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Old 03-31-08, 07:52 PM
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Heating Repair

Have you ever seen the unit fail (does it fire and then turn off or not fire at al then lock out) before you turn it off next time look for a flashing light that will geve you a helpful failure code the code legend will be on the wiring diagram.
 
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Old 04-01-08, 05:51 PM
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Originally Posted by KField View Post
Mkae sure the flame sensor is clean (use steel wool) and that the pilot flame strikes it squarely. If that doesn't help, I would suspect the S89.

Ken
Forgive my ignorance but can you tell me where the flame sensor is located?
 
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Old 04-01-08, 05:54 PM
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Look for the 'sense' terminal on the S89 and follow the wire back to the sensor.

Ken
 
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Old 04-01-08, 05:54 PM
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Originally Posted by mike n View Post
Have you ever seen the unit fail (does it fire and then turn off or not fire at al then lock out) before you turn it off next time look for a flashing light that will geve you a helpful failure code the code legend will be on the wiring diagram.
I've had it fire up only to shut off before getting to temp. Is that what you're talking about. I didn't notice any flashing lights anywhere though. No LEDs on the S89G.
 
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Old 04-01-08, 05:58 PM
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Originally Posted by KField View Post
Look for the 'sense' terminal on the S89 and follow the wire back to the sensor.

Ken
Thanks! I will give it a try.
 
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Old 04-04-08, 05:06 PM
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Originally Posted by RochesterGordon View Post
Thanks! I will give it a try.
Still experiencing the same symptoms. No "Sens" terminal on the S89G - a couple for the valve, ground, and a couple for the HSI. One of the HSI terms for the igniter says sensor but no other leads.

Igniter still stays on, no pilot gas. Will the igniter stay lit on lockout?
 

Last edited by RochesterGordon; 04-04-08 at 06:49 PM.
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Old 04-05-08, 04:36 AM
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No the ignitor will not stay lit after the control determines that there was flame failure. It will recycle depending on the model of the S89. It sounds liek the control is defective. Replace the ignitor also because they don't last forever and this would be a good time to change it.

Ken
 
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Old 04-05-08, 12:03 PM
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Originally Posted by RochesterGordon View Post
The igniter will glow but the furnace wonít fire up.
But then the thread title says: "Pilot on but no ignition".

When the furnace does NOT work, which is the real problem?
 
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Old 04-15-08, 08:07 AM
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Originally Posted by KField View Post
No the ignitor will not stay lit after the control determines that there was flame failure. It will recycle depending on the model of the S89. It sounds liek the control is defective. Replace the ignitor also because they don't last forever and this would be a good time to change it.

Ken
There is a new ignitor currently installed. I'm guessing the the box is bad.
 
 

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