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 🙂

[StirCrazy]

I don't know which places you tried in town, but did no one have a replacement that cross reference to it?

oh, and did you replace the blower motor and clean it up good while it was out. I have a 7912 in my 91 camper and when the motor goes it goes fast. Mine started chirping on initial startup and was gone when it warmed up. A few uses later that chirp turned into a squeal that would last a short while it came up to temp. then about 3 weekends later it decided it would never stop squealing

[Kevinski]

I will probably assemble a list of the small parts I need to build up an entire spare pilot line and fittings assembly, and order them and have them all sent to one of the cross border shipping places for the next time I come down into the US, since Canadian sources for these individual parts seem rare.

[Kevinski]

Hey MarineBob,

yeah I really don't know if you could substitute a more typical two piece with nut ferrule connected for the breakaway fitting. I would imagine if it all fits and doesn't leak, it would be fine.

I since found a listing on the Robertshaw website for 1/8" brass breakaway ferrule fittings (4590-065 is the fitting number), that I'm guessing would be the exact ferrule for my furnace, as the original gas valve is a Robertshaw. And get this, they come in bags of 15 pieces. Robertshaw listing: https://www.robertshaw.com/Products/Heating/Breakaway-Ferrules/4590-065/?cat=2147484294
I searched by that part number and found several sellers online but they mostly seem to only ship to the US. Cost comes out to only about 2 bucks each but the trick would be to find a supplier who would sell you just one or two
Bob, you might very well find the breakaway fitting for your needs somewhere else in the Robertshaw 4590 series of breakaway ferrules:
https://www.robertshaw.com/Products/Listing/?filter=2147484252&categories=2147484294

Oh, and I did notice in the ferrule part description the words "One Breakaway ferrule part replaces the need for an additional nut". So it may be an instance of reducing the number of separate parts hence the number of connections, each one of which is, I suppose, a potential leak point.

[MarineBob]

Good summary of a quest. I have a couple comments and questions I hope someone can help with. My fitting issue was with a pilot on a fireplace insert. I ended up buying a generic replacement assembly for about 1/3 the OEM cost of a single part for my application. My comment is if you need parts, search for a generic to see if it will work….way cheaper and just as good in many instances. Heres my question. Why are breakaway fittings used? Seems like only for pilot applications. And…..are more typical two piece ferule and compression nuts OK to use for these applications on a pilot? Seems to me such fittings would seal without any problems but with gas you need to be sure. The breakaway fittings also seem to be a bit harder to get hold of and more costly compared to 2 piece fittings that seem to do the same thing

[Kevinski]

larry cad wrote:
" and I hope that this thread helps someone else at some point."


Well, that "thread" helped you for sure!

Thanks for the update.

It certainly did!

[larry_cad]

" and I hope that this thread helps someone else at some point."


Well, that "thread" helped you for sure!

Thanks for the update.

[Kevinski]

Just an update, I have the furnace up and running! In case anyone in the future runs into this same problem and finds this thread, here's an update about how I made a replacement pilot gas line with correct fittings.

My solution:

I pirated the gas pilot line from this Dometic pilot assembly I bought from Amazon: Dometic pilot assembly with some but not all correct parts

It was an unknown and a gamble of 40 bucks. The fitting for the Robertshaw gas valve end fit correctly, but the smaller, pilot burner end fitting didn't. So, I had to figure out how to solve that issue next.

The small fitting at the pilot burner end of the gas pilot line, it turns out is a special fitting called a breakaway compression fitting. This might help when searching for a replacement fitting. I figured that out by stumbling across this excellent video: gas pilot line break away fitting installation

The video shows the larger fitting at the gas valve end, but it would be the same for the smaller fitting at the pilot burner end (the fitting is just smaller).

I visited the fantastic, old-school RV shop that is unfortunately about 1-1/2 hours away from me, and was given one of these fittings by the helpful dude there. I unfortunately neglected to take a photo or any measurements of it, but it looked more or less like one of these in these links:

breakaway compression fitting link 1

breakaway compression fitting link 2

Notice on the Resideo site that they can be had in a few different lengths. Not sure what length the one I got from the RV shop was, didn’t measure it but it was just a little longer than the factory one. It did work, though. If you have your old fitting sitting there in your hand, you could measure that.

Once I was back home, I cut off the end of the new Dometic gas pilot line that didn't fit, and installed the new-to-me correct fitting on in it's place. You have to be really careful and slow cutting this tubing with a small pipe cutter, because it's so soft - you'll easily crush it or even bend it out of round. I inserted a small finishing nail into the open end of the tubing to help support it's shape while cutting - another awesome suggestion from the helpful dude at the old RV shop. Seriously, these kind of places are like gold mines for those of us with old stuff.

I have since found a product listing that *might* have the correct fittings on each end, but since the description is poor it's hard to say for sure: AO Smith pilot tubing with fittings

Anyway, once I had the pilot tubing built up, I carefully bent it into shape, installed it into the furnace using a very sparing amount of gas line pipe dope (the oil referenced in the video above didn't work for me, to seal the fittings fully - remember to leak test at pressure!) and voila, it lives.



Thanks for all the help, and I hope that this thread helps someone else at some point.

[larry_cad]

Kevinski wrote:

larry cad wrote:
Two different kinds of ferrules. Also, I believe the one on the left is aluminum and the "ferrule" is actually formed into the aluminum tube with a tool.

yeah they definitely are. Any idea where I could source a ferrule like the one on the right?

Typically the ferrule comes with the fitting and is the ferrule that is required for that fitting. I think the ones shown are suitable for propane, but defer to others to confirm.

I also agree with others that you should heat the hardened goop to free up the fittings.

[Kevinski]

larry cad wrote:
Two different kinds of ferrules. Also, I believe the one on the left is aluminum and the "ferrule" is actually formed into the aluminum tube with a tool.

yeah they definitely are. Any idea where I could source a ferrule like the one on the right?

[larry_cad]

Two different kinds of ferrules. Also, I believe the one on the left is aluminum and the "ferrule" is actually formed into the aluminum tube with a tool.

[Kevinski]

I did manage to get the pilot assembly out to move it over to my existing furnace.
But... the aluminum pilot line sheared off right where it goes into the coupling nut at the gas valve end. I have an extra pilot line with fittings that I managed to find, but I have an issue with the end where it goes into the pilot.
Can anyone tell me what the little ferrule compression ring is called on the end of the gas line? it appears to be only one sided. I need to cut the new line short, and get another one of these little compression rings, and set it on there so the same amount of line extends past it to match what is on the stock assembly. But I don't know what that little compression ring is called to search for one online. It also appears I need one with a different taper. Photo is the new pilot line on the left, end of the old pilot line on the right.

Grrrr, this stuff all seems almost standardized, but not quite....

Edit: or, is the brass compression ferrule on the old pilot line on the right, just a regular olive type compression ring and do they just compress down to look one sided after tightening them down? See second pic for what I mean.

[Kevinski]

ernie1 wrote:
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.

Thanks Ernie, I'll try that if I end up needing to remove that fitting.

[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...