Reuben Saltzman

Where To Look For Gas Leaks

Edina House Explosion The one home inspection item that consistently causes home buyers to ‘freak out’ more than anything else is a gas leak.   Believe it or not, small gas leaks are actually quite common at old houses, and they’re usually simple for a plumber to fix.  Today I’ll share the most common locations for gas leaks, and I’ll share my home inspection techniques for finding gas leaks in old Minneapolis and Saint Paul homes.

The most common place for me to find gas leaks is at gas valves.  Older style gas valves that aren’t allowed any more today are often referred to as lube valves or plug valves.  If you have a Truth-in-Housing Evaluation performed in Minneapolis and the evaluator marks down “old gas valves” or “unapproved gas valves”, this is what they’re referring to.

Lube Valve

Lube valve

These valves are easily identified by a nut or spring on the valve across from the handle; newer gas valves don’t have these.  I would estimate that I find leaks at about one out of every five of these valves.  Gate valves, which should only be used for water, are also common offenders.

Gate Valve

The repair is always simple – replace the the valve.  In Minneapolis, if the appliance being served by an improper valve is replaced, the valve must be replaced at the same time.

The second most common location for gas leaks is at unions.  A gas union is a fitting that provides a disconnection point for a gas appliance.  If the union doesn’t get tightened enough, it will leak.  Notice the bubbles in the union below?  That’s a small gas leak.

Leaking Union

Flare fittings are the last common offender.  Here in Minnesota, soft copper gas tubing is allowed just about anywhere, but it takes a little more skill to properly install soft copper than other types of gas piping.  For a flare fitting, copper tubing gets flared out at the end and connected with a flare nut.  If this connection gets bent or isn’t tight enough, it will leak.  For the record, that nut pictured below isn’t the right type of nut for a gas line… but it’s what I had sitting in my parts drawer as I was writing this blog.

Flare Fitting 1 Flare Fitting 3 Flare Fitting 2

Combustible Gas Detector To find these gas leaks, you can usually rely on your nose.  If I smell a gas leak and nobody is around, I’ll run around the fittings with my nose right up the gas line.  This is a fast way of figuring out exactly where a leak is coming from.  The only problem with this method is that I look very silly doing it.  When I’m inspecting a house and my clients are with me, I use a combustible gas detector.

The only problem with using a combustible gas detector is that they’re ridiculously sensitive, and they’ll often give false positives.  For instance, if there is fresh pipe dope at a fitting, the gas detector will go off.  When one finds a leak with a combustible gas detector, it needs to be confirmed by using a gas leak detection solution; it’s a liquid that does about the same thing that dish soap would – it bubbles if there’s a leak.  To make it easier for the repair person coming in behind me, I also mark the location of the leak with orange electrical tape, and I write “Gas Leak” on the tape, along with an arrow showing exactly where the leak is.

Gas Leak

I’ve heard stories about appliance connectors leaking, but I’ve never found one that leaked. Next week I’ll talk about defects with appliance connector installations.

Reuben Saltzman, Structure Tech Home Inspections – Email – Minnesota Home Inspector



No responses to “Where To Look For Gas Leaks”

  1. Linda Merry
    March 17, 2010, 4:00 am


    Great article! Lots of good information. On average, what should it cost to have someone come in and check for leaks? My home is over 60 years old and would love to put my mind at ease. Shoot! I just had the house inspected for refinancing. Probably could have gotten some info then…



  2. Reuben Saltzman
    March 17, 2010, 4:53 am

    Hi Linda,

    Thanks for reading! If you’re going to hire someone to check for gas leaks, make sure it’s a licensed plumber that can also repair any potential leaks. I’m guessing this would be less than $100.

    Having said that, I don’t think you need to hire anyone to come in. If you have a gas leak, you should be able to smell it. You can buy the leak detection solution that I mentioned in my blog at Home Depot for about five bucks, and you can swab this on any suspicious areas.

    Good luck!

  3. alisa
    March 21, 2010, 5:12 pm

    There seems to have been an epidemic of explosions in Mass this past winter. I heard that it was because the regulators were inside the houses, and not performing correctly. whereas, if they are outside the home, and not performing correctly, the gas is let out into the atmosphere, instead of building up inside the home.
    thank you for your tips on this matter!

  4. Reuben Saltzman
    March 21, 2010, 6:08 pm

    No kidding? I wonder what was different about this winter that caused the explosions.

  5. Gas Appliance Connectors | Reuben's Home Inspection Blog
    March 30, 2010, 4:09 am

    […] weeks ago I wrote a blog about the most common places to find gas leaks, and I said I’d follow up with a blog about gas connectors – those short, flexible, […]

  6. Neil Elliott
    May 22, 2013, 8:45 am

    How do you find and fix a gas leak in the wall. My house has no basement and no attic.

  7. Reuben Saltzman
    May 22, 2013, 11:59 am

    Neil – you would probably need to open up the wall.

  8. Vickie White
    August 30, 2013, 1:02 pm

    Thanks for the article. The gas company found two gas leaks In my house, they shut the gas off and took the meter, which was fine with me. I have friend that does this type of work, my question is, will the gas company accept his work.

  9. Reuben Saltzman
    August 30, 2013, 1:06 pm

    @Vickie – why wouldn’t they?

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