Furnace

[jsb5717]

Originally Posted by GreG L.

I had a similar issue, it turned out to be the black 15 amp fuse that trips and resets itself, mine was tripping soon after ignition and than resetting right away. Swapping it with a regular blue 15 amp fuse solved the issue.

This is a very good thing to check…regardless of the current state of the furnace. Make sure to have a standard blue 15a fuse in place.

That said, if the current issue is that we’re getting open propane valve but no ignition attempt then I would suspect the main board. Maybe it’s been glitchy and has now completely failed.

[pitman44]

Originally Posted by Jamric

Tried furnace this morning after getting it to work with bypassing heat limit switch, now the fan just runs and no ignition! Sail switch or what?

FWIW, I have about 30 years experience in residential HVAC. Much less with RV furnaces. If your ignitor sparks, it's not the sail switch, high limit switch, fuse or many other things. If the ignitor sparks and there's no flame and you're smelling propane out the exhaust, the high probability issue is the ignitor. Take it out and clean it as well as the area the spark strikes. I won't swear to it, but I believe the gap should be about 1/8".

Observe the spark to see if it's a strong or wimpy spark. If wimpy it could be the control board or the cable that that connects the board to the ignitor.

If you get flame that goes out after about 3-4 seconds and the system tries again (usually 3 tries) before locking out, the control board isn't sensing the flame. Clean the ignitor and ground area as above first. If the issue continues with a good flame that surrounds the ignitor, you likely have a failed control board. I don't believe there is a way to test the flame rectification on an RV furnace which is how you'd determine if it's a bad board.

[catch up with the zzzz]

the fouled smell is where I think the problem lies. an exhaust problem does the same symptons. If the gasket is torn or worn this can happen. Assuming the is clear. and not to baddly carboned up, replaced gaskey and the smell persists You may have to pull out furnace and service it.

[jeepman71]

As stated earlier if everything you checked on the electrical side is coming up good check the regulator. You can have enough pressure to run stove top burners and fridge but not the furnace. I ran into this with a previous RV. A lot of frustration, finally called an RV tech. He checked pressure and sure enough it was low.

[Daryles]

Regarding propane regulator pressure.
Does your water heater work in Propane mode?
It is also a high Propane demand device just like your furnace. If it works with the cooktop and oven on AND the fridge (in Propane mode) all on at the same time your regulator is likely good.
Remember, you have two regulators. One on each Propane tank. If you suspect one is bad switch to the other one by turning off the suspect Propane tank.

[pitman44]

Originally Posted by Daryles

Regarding propane regulator pressure.
Does your water heater work in Propane mode?
It is also a high Propane demand device just like your furnace. If it works with the cooktop and oven on AND the fridge (in Propane mode) all on at the same time your regulator is likely good.
Remember, you have two regulators. One on each Propane tank. If you suspect one is bad switch to the other one by turning off the suspect Propane tank.

The water heater consumes at most 10,000 btuh assuming it's not tankless. The furnace consumes at least 30,000 btuh. The advice recommending checking with all the other gas appliances running, assuming you don't have a monometer, is spot on.

The regulator on the door side is a high pressure regulator. It feeds gas to the low pressure on the off door side. If the high pressure regulator is bad, it will only impact things when pulling off that tank. If the low pressure regulator is bad, it will impact things regardless which tank it's pulling from.

FWIW a monometer is a great tool to diagnose problems with gas pressure. A water filled U tube manometer is the least expensive, but still accurate. A digital is more accurate and somewhat more convenient to use. When you test the gas pressure check static pressure first. That's with nothing on. Then turn on everything and check again. It should be between 11"-14"WC in either case.