Furnace Failure

[Jaytalk]

Originally Posted by baehrelw

We had the same problem. We were traveling with 2 other couples both with Jayco and they did not have the problem. We contacted our dealer in Michigan and they never heard of the issue. We contacted a local rv and they were not cooperative. We contacted the furnace mfg and they advised that the unit has a altitude limit of 6000ft. We messed around and adjusted the igniter closer to the gas and the problem was resolved.

It wasn't that the heater didn't ignite. It ignited, but it would only stay on for a second or two, three seconds at the most before going out. Given this fact, what do you think the problem was?

[jd99336]

Originally Posted by Jaytalk

It wasn't that the heater didn't ignite. It ignited, but it would only stay on for a second or two, three seconds at the most before going out. Given this fact, what do you think the problem was?

I still think it may be your thermocouple. If you read my prior post you would see that it would light, burn for a second or two, then go out. The furnace will ignite with gas going to the thermocouple burner which heats the thermocouple, which provides micro-voltage to a fail/safe type of switch. If the thermocouple does not reach operating temp to provide necessary voltage, the valve will close and your furnace burner will go off. It will try this over and over repeating the process. In my case the small pilot flame to the thermocouple was not adjusted correctly, so the thermocouple was not fully in the flame from the burner. This caused it to fault and shut down.

Obviously I can't guarantee that is the situation, I am only saying that your symptoms sound similar, so it is an easy and cheap place to start.

[Sunflake]

The furnace doesn’t have a thermocouple. If it did it would be like your water heater at home that has a standing pilot light, which uses a thermocouple. Your furnace has a flame sensor. Which uses flame rectification to prove that the burners did light. If you have poor flame quality the flame sensor doesn’t complete the safety circuit telling the board that the furnace did in fact light. The fact that you did hear at least something light the fact that it was only for 3 seconds is a classic symptom of the flame sensor not seeing flame and turning the gas valve off.

[Sunflake]

I found this wiring diagram for an Atwood furnace. There are 2 electrodes, one is the spark igniter the other is the flame sensor, the one with the red line. Hope this helps. It would be a huge PITA if furnaces had a standing pilot.

[jd99336]

Ok...I messed up the nomenclature, however they accomplish or fail to, the same thing. Here is a link with a rendering that may or may not be accurate. Flame Sensor

Not sure what it looks like in our units, but the sensor needs to be in or near the flame

[Sunflake]

Needs to be in the flame jd