# rHEEM FURNACE GAS SHUTS OFF AFTER 3 SECONDS



## TERRY38121 (Dec 5, 2010)

I have a rheem furnace the gas comes on lights up then gas valve shuts off i measured voltage at the gas valve 24 volts no flashing led the gas shuts off then the 24 volts starts dropping off about 8 secononds later also the flame rod is good i had a new one and it didnt help and the pressure valve is opening and closing and i ran the flow chart on the panel inside i went thu each step it said to replace the ifc i guess that is the circuit board why does the gas valve shut off then the 24 volts drops 8 sec later also all of the limit switches are closed circuit they have a re set buttons on them i hope if i buy a $200.00 board it fixes it thanks for any input


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## hvactech126 (Nov 11, 2010)

try cleaning the flame sensor first.


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## TERRY38121 (Dec 5, 2010)

*Gas furnace shuts off*



hvactech126 said:


> try cleaning the flame sensor first.


 
i cleaned the flame rod the on that sits in front of the flame right i cleaned it with seteel whool i even replscet it with a known good one from a tankless water heater


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## kenmac (Feb 26, 2009)

make sure the unit has a good ground, make sure ps is staying closed, make sure flame sensor wire has good connection at the board, make sure your limit in the heat exchanger is staying closed.


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## Marty S. (Oct 31, 2009)

Sounds like a gas problem to me terry. Having 24 volts at the gas valve for 8 seconds after the flame dies isn't a board , flame sensor or pressure switch issue since they would all drop the 24 volts first, then the valve closes . Checking the incoming and manifold gas pressures would be my next step.


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## TERRY38121 (Dec 5, 2010)

Marty S. said:


> Sounds like a gas problem to me terry. Having 24 volts at the gas valve for 8 seconds after the flame dies isn't a board , flame sensor or pressure switch issue since they would all drop the 24 volts first, then the valve closes . Checking the incoming and manifold gas pressures would be my next step.


 

note this all started after the gas line was off for a month or two had it 
disconnected while repairing the tankless water heater which rheem sent out a gas valve then a burner then a door switch then a controller / thermostat and asking them to send a circuit board from the get go it finially fixed it with the new board but my rheem furnace had the gas line ryoff of it all this time now i hooked it back up with the same gas line but added a larger gas pipe and flex line to the water heater thinking it was the problem because the water heater never really worked right i think because the size of the gas line and pipe was 1/2 in needed 3/4 now the furnace does not work maybe needs a larger gas feed to it it has 1/2 but it always worked for the past 12 years thanks Terry why does the gas shut off if it has 24 volts to it should it stay open the gas valve if there is 24 volts to it but shuts off then the 24 volts goes away after 3 to 8 seconds i dont remember the exact seconds is there a way to re set the board what are the dip switches for


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## yuri (Nov 29, 2008)

Try use a few periods in your sentences. Our guys won't read novels or reply if it hurts their eyes.

If the line is undersized and it cannot maintain 4-5"WC to the valve when it is open it will drop out. Sounds like you need to upsize your line. We don't use anything less than 1" to feed the furnace, 3/4" for the drop to it and 1/2" inside it.


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## TERRY38121 (Dec 5, 2010)

yuri said:


> Try use a few periods in your sentences. Our guys won't read novels or reply if it hurts their eyes.
> 
> If the line is undersized and it cannot maintain 4-5"WC to the valve when it is open it will drop out. Sounds like you need to upsize your line. We don't use anything less than 1" to feed the furnace, 3/4" for the drop to it and 1/2" inside it.


 
ok cool i can upsize the line but this line has been on it for 11 years,
now i touched the heat rod and it fell apart , this is the ignitor. 
also i noticed years ago the ignitor would stay ignited all the time glowing activated , shouldnt it shut off after the burner is going or is it normal to stay activated while the burner is on seems like a waste of electricity to me but maybe for safety reasons


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## yuri (Nov 29, 2008)

It should shut off BUT it sits directly in the flame so the flame may cause it to glow red. Only way to know is to put a amp meter on the igniter wires to see if it is drawing current.


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## rditz (Jan 6, 2011)

*furnace shutting off after a few seconds*

This has happened to me under two situations..

1) we had a very icy winter and there was an icy/snowy build-up at the exhaust and intake for the furnace. I had called my furnace guy and he said he had dozens of complaints that week and it was as simple as cleaning the area.

2) progamable thermostat battery. the batteries were low.. thermostat would call for heat and then I guess it would drop off and the furnace would shut off. 

These were simple and inexpensive things that resolved my problems. 

good luck


rod


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## tvax1 (Jan 24, 2014)

*May help*

I had a similar problem with my Goodman GMP075-3 gas furnace and your problem could be flame sensor rather than the ignitor problem but my problem was different. Mine turned out to be a blocked exhaust pressure sensor. 

My Goodman would have the ignitor glow and then the gas ignite and burn for about 3 to 5 seconds and then shut off. No code showed at all. The unit is about 11 years old and twice in the past I got the exhaust sensor blink code. With no code showing this time, I first cleaned out the unit(both vacuum and then blow out with a canister vac) and brushed off the flame sensor with steel wool. When that didn't work, and just before I thought I couldn't wait to order/receive and then change out the control board, I thought why not also check the pressure switch exhaust sensor and the tubing. I blew through the rubber tube while connected to the sensor and it was open and you could hear a click of the sensor engaging in the plastic housing. Then I connected the hose to the exhaust nipple and was only able to bow out a little bit. When it was blocked the 2 prior times, it was completely blocked. I used a straightened paper clip and then a pipe cleaner to clean out the metal nipple and was able to get a free/open blow of air through. Reconnected everything and it fired and stayed on!!!!!!!!! I believe the sensor showed no code as it was able to work in the warm-up stage but then under full load, the limited flow then shut it all down. 

So clean out that exhaust air pressure switch including the fitting nipple to the duct that vents out the roof.


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## danpik (Sep 11, 2011)

tvax1 said:


> I had a similar problem with my Goodman GMP075-3 gas furnace and your problem could be flame sensor rather than the ignitor problem but my problem was different. Mine turned out to be a blocked exhaust pressure sensor.
> 
> My Goodman would have the ignitor glow and then the gas ignite and burn for about 3 to 5 seconds and then shut off. No code showed at all. The unit is about 11 years old and twice in the past I got the exhaust sensor blink code. With no code showing this time, I first cleaned out the unit(both vacuum and then blow out with a canister vac) and brushed off the flame sensor with steel wool. When that didn't work, and just before I thought I couldn't wait to order/receive and then change out the control board, I thought why not also check the pressure switch exhaust sensor and the tubing. I blew through the rubber tube while connected to the sensor and it was open and you could hear a click of the sensor engaging in the plastic housing. Then I connected the hose to the exhaust nipple and was only able to bow out a little bit. When it was blocked the 2 prior times, it was completely blocked. I used a straightened paper clip and then a pipe cleaner to clean out the metal nipple and was able to get a free/open blow of air through. Reconnected everything and it fired and stayed on!!!!!!!!! I believe the sensor showed no code as it was able to work in the warm-up stage but then under full load, the limited flow then shut it all down.
> 
> So clean out that exhaust air pressure switch including the fitting nipple to the duct that vents out the roof.


 Since it has been a little over three years, I am sure he has solved the problem by now.


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## Gene S. (Jan 24, 2014)

lol!! I damn near did the same thing!


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## tvax1 (Jan 24, 2014)

*Really?*



danpik said:


> Since it has been a little over three years, I am sure he has solved the problem by now.


Believe it or not, since I came upon this thread in troubeshooting my furnace this morning, I think others may come upon it the same way....EVEN THREE YEARS FROM NOW:laughing:

My purpose was to help anyone out who might need another angle at a solution.
Sorry to have bothered you and anyone else who is offended with someone looking to help out.
Any other feedback on where I can post this to assist others would be more appreciated. Otherwise 

Thanks danpik and Gene S


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