Furnace Pilot Issues

[mattcmyers]

FA 7912 Issue with pilot light
Hi all, long time reader, first time poster...
I have a 1974 boler b-1300. It's got an FA 7912 furnace. The fan works, it's quiet enough, I already bent the blades for that, propane gets to the pilot light housing, as I took it apart and checked, but it's not getting through the pilot orifice (I think that's what its called). I cannot figure out how to remove it and clean it out. Perhaps I need a new one, but mine looks like the pic entitled "pilot." When I google the part I think I need, the picture entitled "New Pilot" comes up. My question is, can I clean the old one up somehow, or do I put in the new one and hook its new thermocoupler into my existing furnace?

[Friz]

I it's anything like the orifice jets on the fridge, is should be able to be cleaned, but do not drill it out or use a wire. There's a spiral thing inside the jet that shouldn't be damaged.

Use a spray can of carburetor cleaner. They usually come with a length of small tubing that allows access to a remote location. Should be able to see through it.

Note: Answer is for suggestion only, not responsible for singed eyebrows or any other fiery events. Let the solvent evaporate before lighting furnace.

[mattcmyers]

Thanks Friz, it's all apart, so I shouldn't have any trouble getting carb cleaner on it. There is certainly no light passing through...

[Darwin Maring]

Soak it in CLR to remove all the rust. The orfice is in Microns so it is really small. Do not enlarge it. Also, The gas control should have an adjustment. Look for it. If after cleaning it and it is the same you may be able to adjust for more pressure. Im Assuming you are holding down the PILOT lite lever.

[mattcmyers]

Yes, I am holding it down. I tried Carb Cleaner and I can now feel compressed air coming through it. The Pilot Adjust screw just above the red Pilot knob is the adjustment you're talking about, right? I have not put it back together yet, I iwll be trying tonight. Might be asking something again tomorrow! :-)

[Darwin Maring]

Havent done it in years but im sure you have an adjustment on the controller somewhere. If the hole is open they more than likely it will work. Good luck.

[Chilliwack Murray]

If you’ve gotten as far as getting air through it you should be able to clean it up the rest of the way. Soak it for another day and go at it with compressed air in the reverse direction and tapping it on the sides. The gas supply to it is extremely low pressure and can’t overcome any restriction. The orifice is small but not really micron small. It should be around .006” (which is about 160 microns I think).


Kind of goes without saying but make sure you clean the supply line to it as well or the rust will end up plugging it again.

[bigangelman]

I would look at a replacement furnace. The newer furnaces have the pilot/ combustion chamber isolated from the interior of the RV. Much safer! Many of them don't have a standing pilot, they light themselves each cycle. If you button up these little fiberglass trailers you risk carbon monoxide poisoning. I couldn't sleep comfortably knowing I didn't as much as I can to keep myself and loved ones safe.

[Chilliwack Murray]

That furnace has an isolated combustion chamber. If it’s thoroughly inspected and not damaged I don’t know why it needs replacing for the sake of a pilot orifice.

By all means have a gas detectors but I just don’t understand why step one in troubleshooting everything always seems to be “buy a newer one”.

[Glenn Baglo]

Originally Posted by Chilliwack Murray

By all means have a gas detectors but I just don’t understand why step one in troubleshooting everything always seems to be “buy a newer one”.

From my recollection of old threads, it's because no reputable gas fitter will work on them for fear of liability.

[bigangelman]

Do some research, I remember over the years that there have been people killed by caroin monoxide poisoning. It's the reason those improvements have been made. Try to buy a new one identical to your old one now. You won't find any. The old fiberglass trailer I fixed up had a gas oven that some sales brochures said could be used to heating! Sometimes improvements are made for the good of everyone.

[Chilliwack Murray]

Sometimes. And other times it’s just lawyers.

Many people are using brand new catalytic heaters that are not vented outside the shell which meet requirements under the right conditions but if something goes wrong there you are much closer to CO poisoning than with this old heater if it’s in good shape.

In the end, do what makes you feel safe after researching and understanding the risks but if new is always the first option a new trailer is probably in order.