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WillK 10-17-2010 05:45 PM

Crawl space gas leak
First off, the gas is off and has been off since before we bought our house. The gas leak was observed in our inspection and we requested the sellers to have the gas shut off.

So I'm about ready to deal with the leak, and with freezing temperatures coming I need to. It's not beyond my ability to completely replace the plumbing if I had to, but I'm considering hiring this out for the sake of getting it done sooner than I'd be able to...

My question is about whether my guess about the more probable location might be correct, and I know of course that any answers I get will be just that - guesses, but I'm hoping to just get an idea what to expect.

Here's what I know. From the meter outside, gas supply penetrates the crawlspace wall at 2 places near the meter. One is a flexible gas line which goes only to the heater, the other is rigid steel pipe which feeds the water tank, dryer and garage (disconnected)...

The rigid pipe enters the crawl space and goes to the back of the house where the water heater and dryer are in the utility room which is behind the crawl space on a slab. The garage is fed from there through (ugh) copper tube. I'm disconnecting that since I don't think the garage heater is safe and heating the garage is a futue project. At any rate, the leak was detected in the crawl space, not the utility room.

Today I made it to the area of the crawlspace where the gas comes into the house for the first time. I noticed that the steel pipe was very rusty after it entered the house. I didn't notice any obvious defects with the flex line to the heater.

The heater was installed some time in the mid-90's I think. It was definitely professionally installed, which is not always the case with this house so it bears emphasizing.

Obviously my suspicion is the rusty pipes is most likely to have the leak... I need fitting, and if I have them I can disconnect from the union near the meter and test for leaks with soapy water, but am I likely to find the leak with the pipe that is rusty or is it possible the flex hose might be the leaker?

My other question is if this is likely to be a repair that will be under or around $300 if I brought a plumber in to do it?

kenmac 10-17-2010 06:15 PM

Hard to say where the leak is . Could be more than 1 leak. Depends on what has to be done to know price. I get 200 to come out disconnect from GM & pressure test. then, time & material to locate & repair leak/ leaks, get inspection

downunder 10-17-2010 06:51 PM

Just a general maintenance suggestion:

Is it reasonably easy to isolate one section at a time, i.e. cap off at a union and turn it back on to check that section? In a similar sense, could you replace a section of the line from the meter into the crawlspace? I'm thinking that it might be easier to replace than try to test/confirm how good the pipe is where it passes through the foundation.

I suppose it depends on how far and complicated your line is, but just replacing might be simpler, cheaper, and most importantly, certain to be good.

Michael Thomas 10-17-2010 06:59 PM

First question, is the "flexible" gas line CSST, or one or more appliance connectors (identified by fixed flare nuts on the ends of flex connectors and either stamping on those nuts or a sliding ID ring.)

WillK 10-17-2010 09:35 PM

I can't be 100% certain, but I think the furnace supply line is CSST... I didn't know what CSST was before I looked it up after it was mentioned here, but it's yellow plastic covering over something that looks like flexible metal conduit, and outside the house the yellow plastic is removed.

BTW, the furnace is in the crawl space, I think on blocks. The house is on 'piers' (stacks of cinder blocks) so the pipes don't exactly go through foundation, they go through fake brick veneer.

The more I think about it, the more it makes sense to just take out all the connections for the water heater and redo them... I could inspect the pipes for reuse and probably resolve leaking joints just by virtue of disassembling and reassembling with teflon tape for gas (yellow). I think I mentioned I'm leaning towards a gas range, and regardless the permit will be the $70 minumum since I'll call it 2x appliance installation (water heater and stove) @ $28 each for the fees, which doesn't exceed the minimum.

Michael Thomas 10-18-2010 05:08 AM


I helps us to help you solve problems if you list your city and state in your profile.

I most locations the gas utility company will come out at no charge and use a combustible gas detector to accurately locate the source of leak(s).

WillK 10-18-2010 07:33 AM

Fixed, thought I had done that.

At this point the gas is shut off and the gas company had locked the shutoff valve, so I am already aware that I need to pay a charge to have it turned back on which would be necessary before any gas leak detector would work. The house has been airing out for over 2 months, so there isn't any sign of leaked gas to be detected.

I'm expecting rain 3 of 5 days this week so I've got time to work inside anyway.

Had I called anyone out before yesterday I'd have had to be shocked if they did go as far into the crawlspace as you have to go to get to the gas pipes without charging. I cleaned out a lot of loose debris - bricks, broken blocks, broken wood, fallen insulation.

rjniles 10-18-2010 07:46 AM

Open the lines coming into the house at the meter, shut off all the appliance gas cocks, pressurize with air and test for leaks. Shutting of the gas cocks before pressurizing the lines is very important as excess pressure will blow the diaphragms in the regulators.

10 PSI is plenty as natural gas pressure is less than1/2 PSI

Use soapy water or a gas leak detector spray;

braindead 10-18-2010 04:59 PM

Check your local regs., most do not allow flex lines thru walls:huh:

WillK 10-18-2010 09:06 PM

Suppose I have to replace that run, which I'd rather not unless the inspector says I have to or I have an easy to implement plan to do so... Can I put in some sort of flexible line, like a 3' appliance hose, so that I can accomodate the house shifting as I add the beams without carrying load in the gas pipe?

rjniles 10-18-2010 09:38 PM

From CSST literature:

Stainless steel gas piping is installed using specialty fittings and cutting tools. Connections can be made in minutes with the correct tools. Striker plates must be installed where the gas lines penetrate wall studs to protect lines from puncture during drywall installation.

CSST cannot be installed in direct contact with the ground. "

Since CSST can be run hidden in a wall, I doubt coming through an exterior wall or foundation wall would not be permitted.

Michael Thomas 10-19-2010 05:06 AM

You can run properly installed CSST though walls, including exterior and foundation walls. You cannot run "appliance connectors" through walls or ceilings, nor "chain" them together. My concern was that someone might have used one or more appliance connectors as permanent gas supply piping, with a resulting leak at a connection (often, the thread types at the various components do not match up when appliance connectors are used in this manner).


for an explanation of what you can and cannot do with these connectors.

Michael Thomas 10-19-2010 05:12 AM

Ideally (and to maintain compliance with many manufacturers' requirements), testing for gas leaks should be done with a noncorrosive leak detection leak fluid (LDF) such as:

LDFs are both noncorrosive and are engineered fluids, and are much more effective than "soap and water" in detecting leaks - the LDF manufacturers typically claim they will bubble visibly at leak rates as low as 1 cu/ft/year!

WillK 10-19-2010 09:58 AM

I've used dish soap to detect leaks under compressed air in the past, but I'll use this:

I figure if I'm not leaking at 100 psi with air, it's not going to leak at lower pressures of natural gas. And I've seen how it bubbles when you do have a leak, it makes it real obvious.

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