Nat. Gas Furnace issues (pics)

IHC Red · Mar 9, 2012

The furnace is Rheeme Criterion II

First image shows the furnace in the off state.

Second image shows the igniter "lit" just before the gas gets turned on.

Third image shows the gas and igniter on.

The gas stays on for 1-2 seconds and then shuts off.

What's going on here ? I've got some electrical experience and I can test things for proper resitance, etc. Where should I start ?

Thanks in advance.

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Gerry....WI · Mar 9, 2012

When I've experienced this its been because of a failed thermal coupling. I'm thinking about a $20.00 part. Probably a specific type or configuration to your furnace.

Lloyd In South Carolina · Mar 9, 2012

My guess,,, somewhere there in the flame there isa thermocoupler or sensor that controls the gas valve. The valve is electric, easy to spot as the gas line passes through it.

If the furnance lights, then goes out the thermocoupler or sensor is not detecting the heat, so it closes the valve to prevent filling the area with gas.

The sensor has gone bad.

L.

teletech · Mar 9, 2012

It's been a few years since I've done any furnace work but you may need to check and or replace the HSI (hot surface ignition) it acts the same as a thermo-couple. It looks like it's in the flame but may not be sensing or generating the proper signal to energize the small magnet that holds the main gas valve open. I could be way off but it's an idea. Chris

David G · Mar 9, 2012

I would agree with the others, the sensor is not detecting the flame. The newer furnace typically have 2 interlocks. The first is draft, the second is flame. The draft sensor failed on mine last week.

IHC Red · Mar 9, 2012

Thanks guys. I believe you were all correct.

Since posting, I saw the "flame sensor", removed it, shined it with some fine sand paper, reinstalled, and now it's working like a charm.

Thanks again. It's always a little scary messing with something for the first time, but it's sure is reassuring when one's efforts pay off.

WGM · Mar 10, 2012

Call a professional.

Anonymous-0 · Mar 10, 2012

(quoted from post at 12:58:12 03/10/12) Call a professional.

GM, responses such as yours are absolutely a waste of internet bandwidth! Go back to sleep! As for me being helpful, I would mark the flame sensors in his pictures, had he not already found & fixed the problem.
If you are always going to "call a professional", why do you hang out with the do it yourself crowd here? Oh, I know, just to heckle! :evil:

Lesformore · Mar 10, 2012

I've had a similar problem with my furnace. I suggest you replace the flame sensor. Cleaning it is only a temporary fix. The factory puts a special coating on them and cleaning takes it off. I will only work for a few months.

Nat. Gas Furnace issues (pics)

IHC Red

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Gerry....WI

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Lloyd In South Carolina

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teletech

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David G

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IHC Red

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WGM

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Anonymous-0

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Lesformore

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