Gas and Oil Home Heating Furnaces - Pilot too small ?

Hey Folks...

Is there any way to regulate the pilot light 'pressure' on a propane furnace?

I have a older 'Dayton' propane wall furnace in my work shop, and lately the pilot light won't stay on. Initially the pilot would light, but somewhere along the heating cycle the pilot would go out and the furnace then would quit heating.

I've replace the thermocouple on the very off chance that was the problem, but as I look through the pilot light 'hole' I can see that the pilot flame is very small, hence not heating the thermocouple enough (my guess).

When I compare it to my propane space heater in the house, the space heater has almost a 'blow torch' pilot, and the end of thermocouple is glowing red.

I've looked all around the gas control valve and see nothing that might regulate the pilot pressure.

The pilot is pure blue, but only ~1/4" long (out from the directional 'flanges'). It now is barely touching the thermocouple, neither of which (pilot or thermocouple) can be moved because they are swaged into the holding bracket. I thought perhaps the pilot might have a 'restriction' hole to regulate the size of the pilot, but I can't get it out to look.

Any suggestions or ideas? I'm not up in the northern states, but still 20 deg is too cold for me.
Regards
Charlie

since it's in your shop, I am guessing it needs cleaning.. There is no screw/bolts holding the pilot assemblly in place by the burner?

Yes, but without a 90 deg phillips, it looks to be difficult (I won't say impossible) to get at the screws. But of course as a last resort I will attempt that, ad try to clean/ream it.

I was just hoping for a pilot pressure regulator.

I've already blown the pilot gas line itself with 100 psi air (after removing it), and also blowing upward through gas line and the pilot orifice.

Do NOT, again DO NOT ream out the pilot orfice!

If you already blown into the pilot tube, then the pressure may need to be adj.

What model of gas valve do you have?

I'll have to go down and find the model number and gas valve id (if there is one)...
By 'ream' I didn't mean make larger so much as find a sewing needle, etc. that would already fit in the orifice and move it around/up-down to clear anything blocking the orifice.

I blew through the disconnected pilot gas line up to/through the pilot orifice, not toward the gas line connection.

Sorry, folks, we've probably at a dead end. The Dayton furnace (I believe that's Grainger's brand) data plate says Model 3E471, but the paper tag on the gas valve has long since faded to all white.

In using an inspection mirror to search the entire valve, the control says 'RobertShaw' all over, but no other numbers or model indicators. The pilot fusible link 'area' says Unitrol, and that's the extent of information except for the basic wiring diagram sticker.

Do you see any kind of cap screw that is flush with the surface of the gas valve. If you do, the pilot adjustment screw is down inside, once you take off that cap screw. If not, back to square one of making sure that the pilot orifice hole is completely clear. The pilot on a propane will even be more miniscule than natural gas. You may want to extract a thin wire out of a fine wire brush to try to ream out the orifice hole. (I have an orifice reaming kit a worker from the gas company let me have, years ago, that is numbered...but that won't do YOU any good.)

I'll look for the cap screw this AM. I have been/am very careful about messing with the valve itself (a replacement would cost 3-4 times what the furnace is worth...) . The number reamer set may corresponded to a numbered drill set, which I have, and boy are some of those drills tiny.
Thanks.

charlie

I'll look for the cap screw this AM. I have been/am very careful about messing with the valve itself (a replacement would cost 3-4 times what the furnace is worth...) . The number reamer set may corresponded to a numbered drill set, which I have, and boy are some of those drills tiny.
Thanks.

charlie


Yes. They need to be tiny due to the pressure. Tinier than even tiny pins, usually.

Let us know how you make out.

Jay, why wouldn't you ream the pilot orifice slightly? I have done this on probably a hundred units( Mostly gas w/h due to the matchhead-sized pilot flames)
I was just wondering where your feeling comes from, bad past experience, etc.

As for the gas valve, a normal standing pilot gas valve could probably be used. I've retrofited a few of the standing wall furnaces in the past. Not alot of fun but possible.

I would do it if the right tools was used.. I just didn't want him to take a 1/2" drill bit and drill the hole bigger.. That's why I went pretty bold on it.

I've heard it happen when a home owner made the pilot bigger and made a bigger mess than good.

I've already blown the pilot gas line itself with 100 psi air (after removing it), and also blowing upward through gas line and the pilot orifice.
Yes but did you blow out and clean the pilot venturi. Pull the pilot orifice and look at the holes in it?? No steel pin but a toothpick works some times.

Is there any way to regulate the pilot light 'pressure' on a propane furnace?

NO because the regulator is not there in the valve or it is blocked out for LP.. Check and see what the W/C is on your line there to the unit. You need 11" W/C. Line size ok? Any traps in the line to it?? Some times when it gets cold the gas can go back to a liquid in a trap

Thanks. That answers my basic question, "Is there a pressure adjustment to the pilot". It is a standing flame pilot, but is now a more lazy, small flame than it used to be, tho pure blue.

I can't remove the pilot orifice/venturi because it's in a bracket that the screws, over time, have become seriously unremoveble short of using an impact driver.

As for the propane line pressure, I didn't measure it. I'm guessing that's one tool I don't have. I have an auto fuel pump pressure gauge, but using that might be tricky :)

The furnace obviously worked successfully for years before I bought it (3 yrs ago), and worked fine for the first 1 1/2 yrs or so. Then it began to exhibit the problem of the pilot going out every third or fourth cyle of heating.

When I first posted this, it wouldn't heat the thermocouple enuf to stay lit, hence my question.

BUT, as of last night, after moving the thormcouple down to the point that the pilot heats just the tip of the thermocouple, the pilot is again staying lit. (The flame has previously had been heating the middle of the thermocouple. Now I don't know if moving it had any effect, or I'm just lucky that it has reverted to staying lit.

My only thought is reaming the orifice slightly larger was to make a larger, lazy flame that would envelope the thermocouple more than now. I have always thought that the lazy flame was a result of too low a pressure to the pilot, and therfore hoped the was a way to increase the pressure.

But as it is now, it's working again, and the forecast high for Thursday is 58, so hopefully this will become a problem to be solved next winter.

Thanks for all the help, advice and assistance. I sincerely appreciate it.

charlie