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Randall, RVIA Certification
Category: RV
Satisfied Customers: 11644
Experience:  RVDA/RVIA Master Certified Technician with many years experience.
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Atwood..7 seconds, stays lit 10 seconds, then the flame goes..plenum

Customer Question

Furnace Problem (Atwood 8531-IV-DCLP)

The furnace lights after 7 seconds, stays lit 10 seconds, then the flame goes out. This repeats three cycles and then the furnace doesn't light off anymore until the power is turned off and on again.

If you repeatedly turn it off and on, so that the burner and plenum heat up, then it may stay on long enough to deliver heat.

I assume that there is some sort of flame-proving device in the valve that has failed. How can I be sure that a replacement valve is needed and not the associated relays or the electronics board?
Submitted: 7 years ago.
Category: RV
Expert:  Randall replied 7 years ago.
Hi: Thanks for coming to Just Answer with your question. My name is XXXXX XXXXX I believe I can assist you with this. The problem you describe is a classic problem we call "flame sense failure" and it occurs when the furnace actually ignites and yet the control board doesn't "see" that. Its job is to shut the gas valve off if no flame is detected. Most of the time this is going to cured by a new control board. If you get one, I'd go with one made by Dinasuar Electronics as they are far superior to the OEM boards. They have a terrific warranty should you ever need it. The other things that can cause this are a bad igniter or one that is not adjusted properly to stay in the flame. The flame conducts current and that is what sends the signal back to the board. This generally isn't a problem on the 8500 series furnaces. Another thing you need to check is the LP pressure at the regulator. This should be done at least once each year. Low LP pressure is responsible for many gas appliance issues. Gas valve failures are almost unheard of on this model. You could take a resistance reading on both of the coils of the valve and see if they are within 10% of each other. If one fails, the valve won't open or stay open. Be sure the contacts on the board are clean as well as the other connections. People that live in humid climates have more problems with this.
My money is on the control board. Please get back to me if you have any additional questions that you feel might be useful in resolving this issue for you. If you find this information helpful, please hit the "accept" tab so I get credit for assisting you. All the best, R.J.
Randall and other RV Specialists are ready to help you
Customer: replied 7 years ago.
Many thanks.
Expert:  Randall replied 7 years ago.
You are quite welcome! I hope you will tell your friends about our service. All the best, R.J.
Customer: replied 6 years ago.

This is in response to the follow-up emails I get concerning the question.

You were absolutely right, the controller was bad and the new Dinosaur controller fixed the problem. The model that RV America sold me was a universal type, and it was necessary to make new mounting holes for the PC board. As you said, the quality of the unit was much superior to the OEM product -- fiberglass PC board with plated through holes like you find in high-end computer products.

Thanks again for your advice.
Expert:  Randall replied 6 years ago.
Thanks for letting me know............and you do have to make an adjustment to the mounting bracket sometimes. They are a great product and double soldered and much higher quality components. I think I have only seen about 3 failures on these in over 7 years. Glad you got to fixed up.................don't forget to have the LP pressure checked on the regulator once a year. Low LP pressure can burn up the burner head and that isn't a cheap repair. All the best..............R.J.