1972 31' w/Propane Furnace "no heat all fan"

[FarHarley]

I have a 72 31' with the original Suburban Propane Furnace. The thermostat works, but no flame and no gas. The propane top burners work and I noticed there is what looks like some sort of tank in the middle of the furnace, I opened it up...tried to manually light pilot with the push pilot mech. no good. No gas present it seems. Any advice?

[Janet's Husband]

Originally Posted by FarHarley

I have a 72 31' with the original Suburban Propane Furnace. The thermostat works, but no flame and no gas. The propane top burners work and I noticed there is what looks like some sort of tank in the middle of the furnace, I opened it up...tried to manually light pilot with the push pilot mech. no good. No gas present it seems. Any advice?

Welcome to the forum from the far reaches of the Tri-Cities.
I would check a few things to start with.
1.) Take a look under the trailer and see if there is a shutoff valve on the furnace line. Make sure it is open.
2.) Try heating the thermal couple before you try and light the furnace.
3.) Make sure you have the thermostat in the on position before lighting.

[FarHarley]

Thanks Gary,
Happy Thanksgiving!
I will do that, Turkey Day morning. I'm new to all this, so where is the thermocoupler located?
Thanks again....

Originally Posted by Janet's Husband

Welcome to the forum from the far reaches of the Tri-Cities.
I would check a few things to start with.
1.) Take a look under the trailer and see if there is a shutoff valve on the furnace line. Make sure it is open.
2.) Try heating the thermal couple before you try and light the furnace.
3.) Make sure you have the thermostat in the on position before lighting.

[eubank]

These heaters have what's called a "sail switch," which basically gates the flow of propane to the burner. What you don't want is a situation in which propane is burning, but the fan quits. The switch is set right in front of the fan and has a little sail-like arm that effectively blows over if the fan works. If the switch is blown over, the propane is ON. If the switch is not blown over, then it assumes no fan, and the propane won't flow.

Now, sail switches are a darned good idea, but the sail-like arm must necessarily move easily (because mere movement of air must be able to move it). Alas, this is also a fairly dusty environment, so sometimes the sail switch gets bits of dust in it and won't blow over.

Last time ours went dead, I ordered a new switch (not that expensive). However, in the meantime I took out the old one and gave it a good blow-off with compressed air. Put it back in, and all has been well ever since. Now we have the old switch still installed (three years), and the new one still in its sealed package.

Anyway, it kind of sounds to me like you've got the symptoms of sail-switchitis: Fan works, no flame. As others have pointed out, check to make sure that the propane is on and making it to the heater. If it is, then maybe it's time to clean the switch with the air compressor.


Lynn

[john hd]

lynn and gary hit on some good points.

in addition, make sure your battery is fully charged or the trailer is plugged in with the univolt running. a low battery voltage will not spin the fan fast enough to trip the sail switch.

if you 73 is like my buddys 74, the gas valve for the furnace is inside, next to it on the right, getting a pilot lit can take a while. lighting the stove certainly helps purge the lines faster.

good luck and welcome to the forum!

john