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Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 22039
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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My name is ***** *****. I am
, I am having trouble

Customer Question

Customer: Hi my name is ***** *****. I am
JA: Thanks. Can you give me any more details about your issue?
Customer: I am having trouble
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Customer: My rheem 80 gas furnace fires up for about 10 seconds then shuts the flame down for about a minute then repeats the cycle
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Submitted: 2 years ago.
Category: HVAC
Expert:  Rick replied 2 years ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can

continue our conversation.

What is the model number of your furnace? it on the furnace rating tag

Customer: replied 2 years ago.
cant find model number. it is a rheem 80 imperial.gas fired forced air
Expert:  Rick replied 2 years ago.

Ok, I can't give you model specific info with knowing what model you have. What you describe sounds like a flame sensing problem.

Customer: replied 2 years ago.
What "flame sensing" part should I replace?
Expert:  Rick replied 2 years ago.

I can't tell you that because I don't have the model number. What I can tell you is that most of the flame sensors look similar to the one in the attached pic. It's positioned in the burner flame. You can try cleaning off the metal rod with steel wool or an aggressive scotch brite pad. Many times that's all that's needed. Turn the power off to the furnace before you try cleaning it.

Customer: replied 2 years ago.
ok I looked for that rod earlier and didn't find it. ill check again. a friend told me blower motor but the blower seems to be working fine. he said it "the blower motor" wasn't sensing the flame and needed to be replaced. your thoughts?
Expert:  Rick replied 2 years ago.

Some older models don't have a separate flame sensor. The ignitor is the flame sensor and these can become problematic as they age. The fix is to install a kit that adds a flame sensor. Your friends theory is not credible. If the draft fan (the blower has nothing to do with the burner staying lit) wasn't working right the burner wouldn't fire up at all.

Customer: replied 2 years ago.
If the igniter is the thing that glows hot and starts the flame, I replaced that last year and it starts the flame good but then 3 seconds later the flame shuts down.
Expert:  Rick replied 2 years ago.

Ok, that doesn't change anything I've said so far.

Customer: replied 2 years ago.
should I replace it again?
Expert:  Rick replied 2 years ago.

That's not likely to fix this. If you have the type that uses the ignitor to sense the flame you need to add a flame sensor. If you have a flame sensor you need to clean it

Customer: replied 2 years ago.
I cant see adding a part that didn't come with the furnace that's been in my basement since 1992.and their is no type of rod in any of the 3 flame tubes to clean.
Expert:  Rick replied 2 years ago.

Ok, if it's that old it's likely that it's one of the units that uses the ignitor as the flame sensor. This was a bad idea and every model since has a separate flame sensor. The flame sensing issue gets worse with age. The fix is to install the retrofit kit that was developed to overcome this design flaw. You're lucky it lasted this long. I've diagnosed your problem and gave you the solution. I'd appreciate a favorable rating.

Customer: replied 2 years ago.
I wont know if you gave me the correct diagnoses till I try and fix it tomorrow. If your diagnoses is correct, ill be happy to give you a positive rating. ill log on then. Thx. Mike.
Expert:  Rick replied 2 years ago.


Customer: replied 2 years ago.
Rick your diagnoses was incorrect. you said it was a flame sensor that caused my furnace to repeatedly shut down. The actual problem was a "stay sensor". This is operated by a vacuum that is connected to the exhaust blower and when it detects resistance it shuts the flame down.
I will leave your rating blank instead of giving you a negative one.
Expert:  Rick replied 2 years ago.