Picture your furnace as being a tin can with a vent to the outside and a fire inside it. When the thermostat calls for heat, the blower starts, the fan's flag switch verifies air movement, then the gas control valve opens and the burner will ignite if enough electricity is being supplied by the thermocouple. The hot air around the outside
of the tin can (firebox, heat exchanger) is then blown into the TT. Air movement from the blower is supposed to be sealed from the combustion area.
There is one very dangerous possible problem.
If the can (heat exchanger, firebox) has ruptured due to rust or simply cracking, the blower will distribute carbon monoxide throughout your TT. People DO NOT WAKE UP DEAD
If there is a rupture in the can, air pressure from the blower is not sufficient to blow out the main burner but probably will
blow out the pilot. Your next job is to verify the integrity of the "can". If you are absolutely positive there is no way for the by-products of combustion (carbon monoxide is one of them) to leak inside, then continue trying to find a cure.
The problem is likely to simply be a weak pilot flame. This might be cured by adjusting it if your gas valve has an adjusting screw. It is usually found under a chrome cap or under a gasketted screw with about a 3/8" diam. wide head. Chrome caps are also used to cover a vent location on gas valves. Your wisest choice
would be to try cleaning the pilot orifice before
attempting adjustment.. Remove it and flush it by sloshing it in a container of warm soapy water. Rinse, dry and reinstall. If you try to use water or air pressure you stand a chance of blowing the orifice out of your fingers and losing it.
attempt to use a sewing needle or pin to clean it. The tiny size of the orifice hole meters the amount of gas and will be destroyed. You can use a soft bristle from a paint
brush if your eye sight is good enough and hands are steady enough to avoid dropping the orifice. The soapy water method is usually sufficient and safest.
If there is a weak pilot flame, it may get blown out when the main burner shuts down.
Take care when reinstalling the pilot, that the gas connection does not leak. All your gas connections should be checked with a soapy leak detector solution. Eliminate the blowing bubbles before lighting
the flame. We would rather not read about Joe creating a rocket ship. Fiberglass is tough, but not enough to withstand a propane
If you feel at all intimidated by attempting this repair, have a professional assume the liability, after making sure they will check the integrity of the heat exchanger. Just because they will attempt fixing it doesn't mean they have been trained by the manufacturer to do the job correctly.
Wishing you a successful cure,
& Ann K.