Fixing Small Leak in Gas Line Connection

Bearsbeets

New Member
Dec 29, 2020
11
Detroit
Hi, I'm hoping to get some advice on how to seal up and stop the gas leak found on one connection location under my gas fireplace.

I smelled a faint gas smell which led me to use soapy water on the gas line connectors. One spot generated bubbles, the connection of the gas line into the metal housing under the fireplace. See attached image as I'm sure I'm describing this poorly. The leak isn't at a simple bolt to screw connection but seems to be at the connection of the threads to the metal housing which is surrounded by a yellowish caulk/sealant.

One image shows a red arrow indicating the leak source. The other two are zoomed out to show the fireplace setup for reference.

Do I need to apply more caulk/sealant or something similar around the seal? Would I need to disassemble anything?

20201229_181851.jpg 20201229_182033.jpg 20201229_182042.jpg
 

DAKSY

Patriot Guard Ride Captain PGRNY R5
Staff member
Looks like it's the brass fitting in the gas valve.
Turn the gas flow off at the RED handle, by turning it
to perpendicular to the gas flow. Loosen the brass fitting
on the short flexible hose where it connects to that fitting.
See if you can get a box wrench or a socket on the fitting &
try to tighten it. Then retighten the fitting on the hose,
& turn the gas flow back on.
Should be a 3/4" fitting. Good luck, & let us know how
you make out.
 
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Bearsbeets

New Member
Dec 29, 2020
11
Detroit
Thanks for the reply. The bubble formed at the connection point of the threads to the metal housing. The brass fittings before that point came out okay on the bubble test. The bubble basically popped up from the bottom of that yellow sealant material.
 

DAKSY

Patriot Guard Ride Captain PGRNY R5
Staff member
The metal housing is the gas valve. In order to tighten that fitting,
You need to disconnect the corrugated tubing BEFORE you tighten
the fitting in the valve, or you may damage it.
Once it's tight, reconnect the gas line & check it again
 
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Bearsbeets

New Member
Dec 29, 2020
11
Detroit
The metal housing is the gas valve. In order to tighten that fitting,
You need to disconnect the corrugated tubing BEFORE you tighten
the fitting in the valve, or you may damage it.
Once it's tight, reconnect the gas line & check it again
Got it, will give this a try tomorrow and post back!
 
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Bearsbeets

New Member
Dec 29, 2020
11
Detroit
Ok, update: one problem fixed, but overall issue of gas smell remains albeit very much less than before.

I tightened the brass fitting into the gas valve about a 1/2 full turn after removing the corrugated tubing. Reattached tubing to the fitting, turned the gas back on, did the bubble test, no issues at all. Yay! Also no gas smell under the fireplace at all as well. Also yay.

However, a gas smell remains out of the top of the fireplace. Very faint and only noticeable when standing directly in front of the fireplace and when the main burner is off. No smell at all out of the bottom or when the fire is on, however I'm able to hear the sound of gas flowing at all times. I know there's a small pilot light but wouldn't think that pulls enough gas to enable a sound to be heard.

Could this faint gas smell above the fireplace be due to the fact that it's freezing outside and cold air pushes into the vent, causing gas and other odors to dissipate elsewhere instead of out the vent due to pressure issues with the cold?

And is actually hearing gas flowing even when it's just the pilot light a bad sign?
 

DAKSY

Patriot Guard Ride Captain PGRNY R5
Staff member
Have you checked all possible seams/connections for gas leaks using the soapy water on the OTHER side of the valve?
If you can smell gas when the pilot is burning, I would concentrate on that line.
Also check the two gas pressure ports on the upper right of the face of the valve.
There are recessed brass screws that need to be seated tightly.
Can you hear gas when the pilot is NOT burning?
 
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Bearsbeets

New Member
Dec 29, 2020
11
Detroit
Can you hear gas when the pilot is NOT burning?
When the pilot is off (turned heat valve knob to "Off" from "On"), the gas sound and gas smell both go away completely.

I had done the bubble test to the entirety of the contraptions and connections below the fireplace itself after securing the brass fitting into the gas valve and noted no air bubbles.

I recently replaced (someone else did the work unfortunately) the thermopile as this fireplace is about 20 years old and had started to shut off. I don't recall if the gas smell was an issue before, but I doubt it was. I'm assuming this gas smell while the pilot is on must be related to the thermopile replacement?
 

DAKSY

Patriot Guard Ride Captain PGRNY R5
Staff member
The pilot tube may have been damaged when the t-pile was replaced.
It's pretty thin-walled & can be easily compromised if the pilot assembly
was moved too far when the service was done.
 
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Millbilly

Member
Dec 13, 2015
211
02648
I use several diagnostic tools to identify gas leaks. To be honest most people's gas leaks are not gas leaks. Dirty fireplaces create other odors than gas leaks, most commonly lots of dust, sheet rock, wood dust, nerf gun bullets, greeting cards, dog fur, on top of the firebox. These odors are commonly misidentified as gas leaks. I would follow Daksy's advise but also thoroughly clean the unit.
 
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Jan 9, 2017
63
Phelps NY
When the pilot is off (turned heat valve knob to "Off" from "On"), the gas sound and gas smell both go away completely.

I had done the bubble test to the entirety of the contraptions and connections below the fireplace itself after securing the brass fitting into the gas valve and noted no air bubbles.

I recently replaced (someone else did the work unfortunately) the thermopile as this fireplace is about 20 years old and had started to shut off. I don't recall if the gas smell was an issue before, but I doubt it was. I'm assuming this gas smell while the pilot is on must be related to the thermopile replacement?
Have the contractor come back that replaced the thermopile.
Very likely he rotated the tubing in the pilot assembly coming from the gas valve. I have seen many leaks in this location, and tightening the fitting usually doesn't fix it. I believe the expansion and contraction,(from the heat) of this compression fitting makes it susceptible to leaks. On some fireplaces, it is almost impossible to bubble test. Not sure how yours is. And of course you have the heat of the pilot flame to deal with.
 

Bearsbeets

New Member
Dec 29, 2020
11
Detroit
It's pretty thin-walled & can be easily compromised if the pilot assembly
was moved too far when the service was done

Very likely he rotated the tubing in the pilot assembly coming from the gas valve.
Thank you for the replies. I very much think this is the culprit. And unfortunately the work wasnt done by a contractor but by my father. He only replaced the TP and admitted he had to twist everything around given it was a tight space to work with.

Would a replacement of the full pilot assembly (TP again included) resolve this issue? (Link: https://www.woodstoves-fireplaces.com/sit/pilot/assembly/?gclid=Cj0KCQiA0MD_BRCTARIsADXoopYJD6jFpY8Ci63HtcU-uNmjuL8NtWG3BvJXXspzUYt8ZcztETA5TocaAh7yEALw_wcB)
 

Bearsbeets

New Member
Dec 29, 2020
11
Detroit
Update: my local fireplace repair shop ordered the pilot assembly for me for about 1/2 of the price listed at the above link, so I went for it. Will update here once I receive and install, hopefully by this time next week.

Side question: would you recommend I leave the pilot on or off over the next week or so while I wait for the part to come in? If on, it only emits a small gas smell when I go right up to the fireplace. If off, I worry about spiders nesting around gas lines that may result in more damage?
 
Last edited:

DAKSY

Patriot Guard Ride Captain PGRNY R5
Staff member
Your call. NG is not toxic until it's burned.
CO is the deadly byproduct of combustion.
If you get spiders at this time of year, I'd be surprised.
 
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Bearsbeets

New Member
Dec 29, 2020
11
Detroit
Update: Replaced the full pilot assembly, issue 90% fixed.

When I pulled out the old pilot assembly, the pilot gas line was slightly loose at the connection to the brass nut, and easily snapped off completely when I touched it. Likely the culprit of the gas leak/smell.

Now only a faint NG smell remains when I stick my nose up against the top grate of the fireplace. No smell below the fireplace. I used to be able to smell the NG while just standing in front of the fireplace before the pilot assembly replacement.

Question: is this faint NG smell something that needs to be addressed? My next step would be the replace the full gas valve, which I'm hoping to avoid.
 

DAKSY

Patriot Guard Ride Captain PGRNY R5
Staff member
All gas should be INSIDE the fire box.
Did you seal the hole in the bottom of the firebox
with RTV after you replaced the pilot assembly?
If you did, then if you can still smell gas from the fireplace itself,
the only way that can happen is if the seal on the glass is compromised.
 
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Bearsbeets

New Member
Dec 29, 2020
11
Detroit
Did you seal the hole in the bottom of the firebox
with RTV after you replaced the pilot assembly?
This I did not do. There wasn't any sealant under the old pilot assembly when I replaced it, so it didn't cross my mind. Will add this tomorrow and hopefully this fixes it! Will post back - thanks.
 
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Bearsbeets

New Member
Dec 29, 2020
11
Detroit
the only way that can happen is if the seal on the glass is compromised.
Update: small NG odor remains. Again, this odor is only noticeable when I go right up to the top grate of the fireplace and the two feet of air space above. No odors in front or below the fireplace.

The RTV sealant was a good call regardless. There was a sizeable hole for the pilot assembly which I've closed off now.

Given the persistent odor, it seems like the next step is to check the glass door seal. Everything looks in order with the seal, no obvious gaps and no areas where I can hear or specifically smell the NG in excess. Is there a recommended way to check the seal?

I'm losing steam on this troubleshooting given other house projects going on and the odor isn't noticeable unless I get right up in there, so it may take some time for me to attempt any additional fixes. I would call out a professional but I don't know what they would do that I haven't already.
 

DAKSY

Patriot Guard Ride Captain PGRNY R5
Staff member
You can try the "dollar bill" test,
but it will take some time to complete
because of the amount of gasketing.
Make sure the unit is cool.
Undo the latches & place a dollar bill on
the frame, 1/2 INSIDE & 1/2 OUTSIDE of the unit
& relatch the front.
Grab the dollar & pull it out.
If it comes out with minimal effort & there
is NO drag on the bill, the gasket in the area isn't sealing.
Repeat all the way around the front.

Just for grins, try your bubble test on the REST of the gas line
under the unit & everywhere there is a connection.
Make sure everything is tight.
 
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Bearsbeets

New Member
Dec 29, 2020
11
Detroit
You can try the "dollar bill" test,
but it will take some time to complete
because of the amount of gasketing.
Make sure the unit is cool.
Undo the latches & place a dollar bill on
the frame, 1/2 INSIDE & 1/2 OUTSIDE of the unit
& relatch the front.
Grab the dollar & pull it out.
If it comes out with minimal effort & there
is NO drag on the bill, the gasket in the area isn't sealing.
Repeat all the way around the front.

Just for grins, try your bubble test on the REST of the gas line
under the unit & everywhere there is a connection.
Make sure everything is tight.
Very much appreciated - thanks. Will give the dollar bill test a try & again the bubble test and report back