Heater Help

[Joe Mielke]

I have been having problems with my heater for a long time. Normally we just use an electric heater but I have been doing a lot of boon-docking and I need to get the propane heater working.

I am able to light the heater just fine. I turn on the thermostat, turn the temp up, wait for the fan to come on and light the pilot. I then turn the switch to ON and the heater comes on fine. The thermostate is set to the normal temp and everything gets warm and the fan shuts off. Before the next cycle of heat the pilot goes out! I check the pilot several times over a half hour or so but I can't "catch" it failing.

I have replace the thermocouple a couple times and even repositioned to get it in the flame.

I am stumped. Do I ned a new heater? Could it be the fan sensor (how do you test? This is a 91 Bigfoot so is it just to old to fix?

Any ideas or should I just go to Camping World and let them fix it?

[Doug Mager]

here might be a slight kink in the line to that 'couple (it COULD happen)!! Quite often in instances like this, one might suspect the thermocouple but if you have replaced it, you need to look elsewhere!!!

[peterh]

I have replace the thermocouple a couple times and even repositioned to get it in the flame.

If you've replaced the thermocouple the problem is most likely your gas valve control box.

The thermocouple system has two parts: the thermocouple which makes electricity when it gets hot, and a solenoid gas valve which opens the valve that supplies gas to the pilot light when it has electricity.

The most problem-prone part of this system is the thermocouple, which wears out after it's been through a number of heating & cooling cycles. So it's a good bet that, if you're having problems keeping the pilot lit, that's the thermocouple's burned out, but the solenoid can go bad too. If the solonoid burns out or gets sticky the pilot light goes out even when the thermocouple's good.

SInce you've replaced the thermocouple it appears you need to replace the gas valve control box or whole furnace unit. Gas valve units are $100-150, where a whole furnace with electronic ignition (no pilot light or wasted gas) runs $400-450. Either way you go please make sure you understand how to fit, pressure check, and purge a gas line before you muck around with your trailer's gas lines or have the repair done by an RV service place.

--Peter

[Gerry]

I just had big problems with my furnace this year but of a different sort.
My pilot stayed lit but the furnace would not light.
I learned a few things that may help.
1) make sure the valve on your tank is FULL OPEN.
2) the thermo couplin has nothing to do with pilot (mine was the problem but pilot stil stays lit)
3) an oily residue can build up in gas lines - I disconected my lines and blew out with compressed air and all gas appliance work much better the flame on stove top is about an inch higher then before.
4)It takes a lot of power to open gas valve

These are the things learned this spring and yes I got mine working.
Gerry the canoebuilder

[Joe Mielke]

Thanks for the great advice! I will try to clean out the lines and if that doesn't work I will probably have it replaced.

I think I would rather get a newer unit and get rid of the pilot anyway.

- Joe

[Kurt & Ann K.]

Joe,
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.
Do NOT 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 explosion.

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,
Kurt & Ann K.

[Gerry]

All great Points by Kurt and I did fail to mention that I did adjust the pilot screw (not under any chrome cover on my gas valve) to see if it wasn't my problem.
Another easy check is if it has an emergancy valve shut off link that I have infront of my DuoFlame furnace frome the late 70's.
This is a fusable link that is normaly closed and in case of fire it will open cutting all gas to unit so with a multi tester set on OHMS see if this lets power t hourgh.
Good luck and be safe.
Gerry the canoebuilder

[Joe Mielke]

Ok, OK. I believe that Kurt is correct is identifying the issue!

I am very mechanical and I am not at all intimidated but I believe that there is a major issue with the pilot and with this furnace. I am not seeing a nice blue flame and instead see this major puffy fireball (lots of air and no "squirt" of gas).

I have decided to replace the whole furnace. I can get a drop in replacement and the new one will not have a pilot. This should make it easier to use and a whole lot safer.

I also am upgrading to a carbon monoxide alarm.

Thanks for the great advice!

- Joe

[Gina D.]

Kurt knows gas.

[Kurt & Ann K.]

Joe,
That should fix the problem for sure. Actually, I was hoping to hear how you repaired the old one.

Gina,
Was that a compliment or an insult

Kurt & Ann K.

[Joe Mielke]

Final report,

I purchased an new furnace and it was a nice drop in for the one I had. The new one used the same thermostat and after a cold weekend in Northern Minnesota it worked great. It does not have a pilot so you just turn it on and set the temp and it heats. It worked great!!!

I also put in a CO alarm just in case.

After taking out the old furnace I beleive the problem was that the pilot nozzle was damaged and it was to "open". I believe the previous owner messed with this and that it never worked right.

As a side note this was the first time we used the fridge on propane and it woked great!

Thanks for the good advice.

- Joe

[Gerry]

Thanks for the good advice.

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Joe, Good to hear all is working now and is safe!
It is worrysome when one is working on a gas problem and they suddenly drop all Forum communications
Gerry the Canoebuilder