Pilot tubing replacement

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  #1  
Old 07-28-20, 11:35 AM
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Pilot tubing replacement

I have a sight gas leak right before the hardline connects to the nut. This is an easy replacement but is any sealant or thread tape needed?
 
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Old 07-28-20, 05:51 PM
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Would that be a slight gas leak ?

A thermocouple sits in the flame and generates a small voltage to hold a gas valve open.
It connects to a gas valve with a small nut but there is no gas in it.
Can you post a pic of it....... How-to-insert-pictures.


Generic thermocouple.
 
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Old 07-28-20, 06:43 PM
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I can't update the thread. The leak is inside of the pilot flame just inside of the nut. We tested with a meter. The replacement tube has threaded nut on both ends that need to be replaced. Do I need thread tape on that or any sealant?
 
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Old 07-28-20, 07:03 PM
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Gotcha. Pilot supply tubing leak.Title corrected.

Does it look similar to the picture ? Maybe a little fatter but the nuts spin loose ?
That is a flare fitting and doesn't usually require any sealant. The nose is shaped to do the sealing.

You could put a small amount of pipe sealant on the threads but usually the gas leaks between the fitting and the tube and there isn't a way to seal that. In a pinch..... if tightening slightly doesn't stop the leak.... you could put a very small amount of sealant on the beveled end but it cannot get into the pipe.

Pipe thread sealant


 
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Old 07-28-20, 07:48 PM
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100% match. Thank you sir.
 
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Old 08-07-20, 02:05 PM
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I lied. The end that connects to the main gas housing is male but the gas valve near the thermocouple is female. I searched Home Depot and couldn't find it. Is there a technical name for it?

EDIT: No clue how old the pilot assembly is. Does it make sense to just buy a new one? $14 bucks for both vs like $8 or so for the line. The one below is for a hot water heater but it looks identical to mine.

https://www.amazon.com/Heater-Assemb...36&s=hi&sr=1-2
 

Last edited by sagosto63; 08-07-20 at 02:20 PM.
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Old 08-07-20, 09:01 PM
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Sometimes your better off replacing the entire assembly.
One good thing is you'll be starting with a clean pilot orifice
 
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Old 08-07-20, 09:03 PM
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Is that universal? It says hot water heater.
 
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Old 08-07-20, 09:09 PM
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It says universal but I doubt it will fit all water heaters.
 
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Old 08-07-20, 09:11 PM
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Fire place ?

As long as it fits the gas valve, Iím good right ?
 
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Old 08-07-20, 09:38 PM
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It's not sized to your burner. You may have to adjust the pilot flame.
Doesn't your fireplace have a thermopile too that sits in the flame ?
 
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Old 08-07-20, 09:41 PM
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Mine looks identical to the one in the replacement. How do I tell if the flame is too high or low ?
 
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Old 08-07-20, 09:52 PM
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Give it a try. If the pilot stays lit reliably.... it's big enough.
Check the burner after installation to make sure it ignites cleanly.
 
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Old 08-10-20, 09:07 AM
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The pilot light appears quite a bit smaller than the old flame. I didn't measure the old but the new flame is about 1/2" and a bit "noisier" but it lights right up without any issues and the flame in the logs look identical. It's also behind closed glass door so I doubt I will ever hear it. Any concerns?

PSEG (gas company) will test it today for leaks.
 
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Old 08-10-20, 01:58 PM
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PSEG detected a gas leak right at the gas valve. I guess it's possible PSEG misdiagnosed it or got readings near the gas valve tubing which is 2-3" away from the gas valve output line. Or, I cross threaded and ruined either the valve or the new line? I am not sure how given how easy it was to tighten down the grommet/nut. Are we sure I don't need any sealant? I didn't notice any on the old tube connections.
 
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Old 08-10-20, 06:12 PM
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You could use a tiny bit on the threads and a tiny bit on the flared end but it's normally not required.
Make sure you don't get it into the tubing.
 
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Old 08-10-20, 06:58 PM
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The gauge has 400-900 ppm reading at the outlet of the gas valve. It doesnít seem that sealant would fix that given itís normally required. Is it possible thereís a crack in the valve ? I guess the new pilot could have a crack or be leaking.
 
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Old 08-10-20, 07:52 PM
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I guess the valve could be leaking. It's normally a connection point leaking versus an actual valve problem.
 
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Old 08-10-20, 09:50 PM
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Hmm. I'll replace the pilot with a new one to rule it out.
 
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Old 08-12-20, 10:53 AM
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I made no changes and did a quick soap test. No bubbles ANYWHERE with pilot light on and fireplace turned on. No gas smell either. Is it possible their unit got some sort of reside? After install, I light the flame for a few seconds to a minute max and shut it all down. I see a SLIGHT leak where the control knob that turns pilot on/off in the front but nothing where the gas company identified a leak. Should I tighten down further? Finger tight or tight with wrench?

Cliff Notes:

Gas company identifies leak at the gas valve's nut. I replaced entire pilot assembly and now they find a slight leak where the gas tubing meets the control valve. I BELIEVE I saw 400-8XX going up and down. PPM? Unclear what the unit of measure is.
 

Last edited by sagosto63; 08-12-20 at 11:12 AM.
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Old 08-14-20, 08:42 PM
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Update. Still no visible leak using a soap test. I've read NUMEROUS sources that you should not use teflon tape (white or yellow) but some sources say it's OK. I need to stop the leak and I am running out of ideas other than tighten it a bit more or replace the entire pilot assembly.
 
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Old 08-22-20, 07:36 PM
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I contacted a HVAC and he told me to contact a local fireplace store and that the control valve is unique to the fireplace? The fireplace store said they need to know the manufacturer to replace it. It could be a 20+ year old unit and there's no markings as to the manufacturer. I can't just replace the control valve with any generic?
 
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Old 08-22-20, 10:58 PM
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Is there a make and model ID tag on the fireplace ?
No.... the valves are not universal.
 
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Old 08-24-20, 08:41 PM
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Sorry -- I missed this. The control valve connects to a generic gas line. I am confused about why that would not be generic especially since the gas valve and thermocouple is generic? It's a Marco and I put the info on the label below. Oddly, I don't see a 'blower' but I do see a green line that goes down into the vents below the pit. I suspect it is very inefficient without a blower. The dampner doesn't appear to be working as you cannot close it. There's a bolt or something that prevents the dampner from completely closing the opening to the chimney. Appears to be a safety? There's a level on the right that appears to be for fresh air but unclear if that works either.

Marco
Model 792864B
Door kit 793412
Grate 498859
Blower kit 793623
 

Last edited by sagosto63; 08-24-20 at 09:29 PM.
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Old 08-25-20, 09:47 AM
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I spoke with a fireplace store and they said Marco went out of business like 20 years ago and said that the gas control valve is generic and the manual one like the one I have is $155 and the remote operated is $395. I didn't get model #s but he was clear when he said it was generic.
 
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