Heater

[Harley97]

I have a 2018 Thor 24HE. The Atwood heater does not want to work. When I turn on the heater the fan comes on and sometimes I can hear the heater attempt to fire. Other times it doesn't even try.

I have propane flowing. I have tried lighting the heater while the stove is running and after running the stove with no luck.

I checked the sail switch and it is as clean as a whistle.

Any other ideas?

 

[phalexander]

I have a 2018 Thor 24HE. The Atwood heater does not want to work. When I turn on the heater the fan comes on and sometimes I can hear the heater attempt to fire. Other times it doesn't even try.



I have propane flowing. I have tried lighting the heater while the stove is running and after running the stove with no luck.



I checked the sail switch and it is as clean as a whistle.



Any other ideas?

Bummer. Check that the igniter is in the proper position close to the burner. Also make sure the burner tube is clear.

 

[javelin-THOR]

I have a 2018 Thor 24HE. The Atwood heater does not want to work. When I turn on the heater the fan comes on and sometimes I can hear the heater attempt to fire. Other times it doesn't even try.

I have propane flowing. I have tried lighting the heater while the stove is running and after running the stove with no luck.

I checked the sail switch and it is as clean as a whistle.

Any other ideas?

Your description of spark attempts sometimes and not at other times sounds like a loose or poor electrical connection in the fan proving circuit of the furnace. Your guess at the sail switch is a good start. The fan starts when there is a call for heat, so the 12vdc is OK and the thermostat is calling for heat OK. The proving circuit “usually”consists of the sail switch in series with the high temp limit switch connecting to the control board. If the proving circuit fails (open/bad connection) no sparking attempt will occur initiated by the control board. Check your proving circuit wiring connections are clean and tight in the furnace. Worst case it might be something strange like a crack in the control board copper trace that opens/fails sometimes and works other times. A multimeter to test the various proving circuit components might come in handy if you visually can’t find the bad connection.

 

[16ACE27]

Or just a wet, or bad control board.

 

[javelin-THOR]

Just a followup comment. If your furnace is sparking several times and not lighting; then after attempting to light several times, but still not lighting; then won’t try sparking again; the control board may be locking out. That might also explain not hearing more sparking sometimes from your description. You need to turn off/down the thermostat below the call for heat threshold for a short time to reset the control board and then it should resume the sparking attempts again when you call for heat again. If this is your situation then you need to check further into the combustion procedure (gas, gas valve opening, smell gas? Spark not igniting gas; flame sensor mis-adjusted etc.). Check the manual for your furnace as it may also have LED trouble codes that will tell you what fault is occurring.