replacement gas pilot line and thermocouple

[Kevinski]

Hello all,

I've tried a bit of searching on the forums but couldn't find anything relevant.

Basically I'm trying to answer the question, can I use any 1/8 inch gas pilot line and any universal thermocouple to repair my furnace, as long as they have the correct fittings/ferrulesfor where they thread into the gas valve and pilot assembly mounting plate?


Backstory - I have an older Hydroflame 8012 P furnace in my truck camper. A previous owner broke the pilot gas line and removed the thermocouple. Likely while trying to diagnose a problem. I didn't receive either of the old broken parts so can't say for sure what they looked like. I do however still have the mounting plate with the pilot end thinamajig, the igniter electrode, and the pilot orifice which is a start. I would just buy a new complete pilot assembly but the part isn't made anymore, and doesn't seem available anywhere. I'm keeping my eyes open for a used donor furnace but no luck so far. So

Any and all opinions welcome 🙂

[ernie1]

That yellow goop you see on the gas line is a gas line thread sealant like a product called Rector seal. Becomes flexible when warmed up. I would try a six point flare nut wrench and a hammer to strike the end of the wrench on both nuts that you are trying to loosen. A little bit of heat would probably help loosen the larger gas line nut but I wouldn't overdo it.

[Kevinski]

I'd also like to remove the pilot line from the pilot assembly plate so I can clean up the orifice, etc., and if nothing else have it in a better state so that I could easily remove and clean while on the road in the future. But, that brass nut and threads look like this... any thoughts about loosening it other than waiting for the Kroil to take more time? it's a tiny 8mm bolt, and this pilot line and assembly are basically Unobtainium, so I need to be pretty careful not to bung anything up...

[Kevinski]

This is the "new" old furnace. You can see the dried sealant where the main propane line fitting is screwed into the gas valve. My other, current/not working furnace doesn't have this.

The brass fitting at the 1/8" aluminum pilot line is the one I'd need to loosen to be able to move the whole pilot assembly to the other furnace.

[Kevinski]

Okay, a small update. With luck I managed to find another furnace, the exact same model as my current one, with an intact pilot assembly and thermocouple. yahoo!
I'm now in the process of combining parts from this new used furnace into my old/non functional one. But I'm stumped getting connections at the gas valve loosened. Any tips? the connections look like they have some kind of goop holding them together, which is now quite hard. I have used a bit of Kroil on the thread to no avail (if you're familiar with Kroil, if it doesn't do the trick, I don't know what will). I'm pretty loathe to just reef on the small connector nuts for obvious reasons. Is this a place where a bitnof heat might be used, once I make sure all residual propane is gone? I'll include a photo of the sealing material if I can figure out how to post an image.

[C_Schomer]

You might even be able to find that 1/8” pilot gas line on an old residential water heater or luckily you can find that kit that is shown. LP pilot orifices are usually .013 inch.Plain Jane thermal couples are normally 30 mV open circuit. The 250, 500 and 750s were called pilot generators and they would operate the millivolt gas valves directly, for the very old buildings that didn’t have electricity yet. I used to work on a lot of that old stuff.
All the 30 mV thermal couples I saw had the same electrical end and if you look closely it’s a very odd double thread. Craig

[Kevinski]

Thanks Gdetrailer,

lots of good info here. I do have a universal thermocouple on hand that came with the camper, but the little threaded adapter doesn't fit the assembly mounting plate - the thread size and pitch doesn't match. Doesn't seem like any of the thermocouples I can find online actually say what the adapter thread pitches are, you just have to guess. I did find "new old stock" Jade thermocouples on canadian ebay, so maybe those threads would match.

And as long as the various gas pilot line kits all use the same standard ferrule threads, might be able to lick this.

[Kevinski]

larry cad wrote:

Kevinski wrote:
Hi BurbMan, you either have the HF8012 D (D stands for direct ignition), or the newer HF8012-II. Mine is the older HF8012-P and it definitely has a pilot. It was tough to even find a parts diagram for it.

Did you find a parts diagram??

yes, I found and printed a copy the original manual complete with parts list and exploded parts diagram. Of course the part descriptions aren't super useful, but the diagrams have helped.

[larry_cad]

Kevinski wrote:
Hi BurbMan, you either have the HF8012 D (D stands for direct ignition), or the newer HF8012-II. Mine is the older HF8012-P and it definitely has a pilot. It was tough to even find a parts diagram for it.

Did you find a parts diagram??

[Gdetrailer]

Sorry, dreaded double post 😞

[Gdetrailer]

BurbMan wrote:
Ah OK, mine was from a 2002, that furnace looked like it was from Fred Flintstone's house, I didn't realize they made an older version with a pilot light...

That should work, I would think getting the right specs on the thermocouple would be more critical.

Clicky for the above link.

Thermocouples are pretty ubiquitous.. Output typically 750mv.

Problem you might run into is too long or too short of wire and possible different mounting configurations.

Typically you should be able to buy a thermocouple replacement kit, the kit contains several mounting adapters which should handle issues you may encounter with mounting the Thermocouple properly.

For lengths too long, OP will need to gently roll the excess wire up outside the burner chamber.

Typically available in 18", 24" and 36" lengths.

The only concern I have is if the gas valve they have on the furnace uses a non standard electrical connector size or configuration..

I did find a complete universal thermocouple AND pilot tubing assembly kit HERE for $19..



The length is 24" so if it is too long, OP will need to roll not only the thermocouple wire in a roll but the pilot tubing also. Not sure if that will be a issue for the pilot tubing or not, just don't want to kink the tubing so care needs to be taken.

[BurbMan]

Ah OK, mine was from a 2002, that furnace looked like it was from Fred Flintstone's house, I didn't realize they made an older version with a pilot light...

That should work, I would think getting the right specs on the thermocouple would be more critical.

Clicky for the above link.

[Kevinski]

Yes the furnace is pretty old, it dates from 1989. But it appears in good shape, very little corrosion visible. I bench tested the fan and it runs smoothly and quietly, which is good as it sounds like the motors in these don't have a great track record for longevity.

Anyway, would a new pilot line be as simple as just picking up something like this and installing it? obviously I'd try to find something shorter than 5 feet!
https://www.rsl.ca/Catalog/hvacr-supplies/pipe-and-fittings/pilot-tubing-and-fittings/robertshaw-aluminum-pilot-tubing-with-fittings-1-8-x-5-11-291-rsw

[Gdetrailer]

BurbMan wrote:
I had the same furnace, and there's no pilot. According to the parts diagram it's electronic ignition. Are you looking for the igniter?

The one you had, may not be the same as the OPs.

Hydroflame 8012 "P" is not the same as Hydroflame II..

"P" is for Pilot..

The II is DSI..

I had a 1980s TT which had a 12K BTU Hydroflame, don't remember the exact model, but it indeed had a pilot light that had to be manually lit.

I suspect as long as the pilot tube is correct dimension and has the correct fittings it should work. Just need a means of transporting the pilot light gas to the pilot lite at the burner..

A universal Thermocouple as long as you have one with the correct electrical end fitting probably would work and if you can find one that isn't too short or too long of wire.

I would be much more concerned about the condition of the heat exchanger as you are dealing with a 40+ yr old furnace..

[Kevinski]

Hi BurbMan, you either have the HF8012 D (D stands for direct ignition), or the newer HF8012-II. Mine is the older HF8012-P and it definitely has a pilot. It was tough to even find a parts diagram for it.

[BurbMan]

I had the same furnace, and there's no pilot. According to the parts diagram it's electronic ignition. Are you looking for the igniter?