Furnace stopped lighting.

[jerry d]

My furnace worked fine all winter. Have towed 2000 miles, and now its not lighting. This is a Surban brand pilotless furnace. The blower comes on when I set the thermostat to heat, but it does not ignite. Anyone know what and how to check?

[6PackCharlie]

Did you turn off your propane? You may have air in the line to the heater. Are you hooked to shore power or are you trying to get the heater to light using the batteries?

[TG Twinkie]

It could be a number of things. Sail switch is a common problem. If it is pilotless it must have some sort of heating element to light the burner. If you know the model # you may be able to find a trouble shooting manual on line.

[Bigjohn59]

Just had a similar problem with the furnace in my 78, If you take the furnace out of the case and hook twelve volts to the power and thermostat wire you can check sail switch operation with a test light or you can test the sail switched with no power and a multi meter, if the sail switch tests good then you need to check your module board, out on the bench when you hook up power the blower should run and there should be power on the gas valve within 7 seconds, you should also get spark from a coil mounted on the module board, if the module board has power going to it and not out to the gas valve you probably need a board, that's what mine needed, just check within the seven seconds or the power will stop because it senses no flame, good luck!

[perryg114]

Mine was doing what yours was doing and it was the board. If there is power to the board then it is not the sail switch. So as I understand it the blower comes on when you raise the thermostat then the sail switch closes and then the control board opens the gas valve and a few seconds later it tries to ignite the furnance. You will hear a ticking noise when it is sparking. Usually, it will continue to spark for a while after it ignites. When the furnace heats up you will hear a click and that is the thermal switch for the blower relay that makes sure the blower stays on when the furnance is hot and the flame goes out. When the furnance is cool the blower turns off.
Perry

[jerry d]

Thanks to all.
Can the sail switch be reached without pulling the furnace?
Also, is there a exploded diagram of the entire furnace that anyone knows of?
I would like to make repairs with the unit in place if possible. Its under the range in the kitchen, with only front access. Dont really want to remove the range if it can be repaired in place. Thanks.

[perryg114]

I think the sail switch is at the back and it is not accessable from the front. Measure the voltage going to the control board. It there is no voltage there when the blower is running then it is the sail switch.

This might help a little.

http://bryantrv.com/docs2/docs/ntseries.pdf


Perry

[Alden Miller]

I had a similar problem with my furnace in our 1981 Excella.

I called the RV dealer and he told me the most common problem was an accumulation of junk in the burner. I took the access panel off the front of the furnace, removed the burner (it's just like one on a propane grill). I cleaned out the accumulated rust and dirt from the bottom of the burner and that fixed it.

I picked up a new gasket for the access panel and that was it...

-Alden

[arodriguez60]

Here is a service manual for the nt series with the OOps Perry already sent you the link. On mine it was the limiter. It now works great!