Q: I read your recent column about how to deal with old gas lines found in houses. My 100-year-old house has several. I have not yet found anyone who can tell me whether any of the pipes are still in use.
My assumption has been that the ones for the lights are neither hot nor connected to the gas lines for the water heater and stove.
Your article described how to remove such pipes, which clearly presupposes that the pipes are not connected to any gas source. I want to be absolutely sure that this is the case.
A: A wise attitude. Our reader stated in no uncertain terms in last month’s column that the lines for his gas-lit wall sconces were abandoned. We took him at his word and proceeded to tell him how to get rid of the old pipes in such a way that he could effectively patch his plaster walls.
You’re not sure whether your old gas lines are abandoned. Assuming they are would be foolhardy. Be safe. It’s better to verify that the lines are dead than charge ahead and risk disaster.
Readers Jim and Jayne Matthews told us this story, giving us pause and proving the point:
"We purchased our 1901 home in 1986. In opening a wall to do some minor remodeling, we discovered the old gas pipes. Our contractor took out the ones he could see and capped off the old pipe from the street.
"He installed a single new pipe from the street to our kitchen and heating system. The following month our gas bill dropped from about $15 to $2, with no change in usage. The pipes had still been live and had been leaking gas for a long time."
We’re not surprised. Fortunately, nothing bad happened. …CONTINUED
To find out whether the pipes to old gas lights are still live is relatively easy, but it will require some care. You’ll need a crescent wrench, two 14-inch pipe wrenches, a spray bottle and some dishwashing liquid.
First, as a safety precaution, on your gas meter you’ll notice a valve with a rectangular bar. The bar will be running the same direction as the riser pipe. This means the gas is flowing through the meter into the house lines. If something goes wrong and the pipe you are working on starts spewing gas, go to the meter and, using a crescent wrench, turn the rectangular bar perpendicular to the pipe. This shuts off the gas to the house lines.
Now back to your detective work.
Mix some dishwashing liquid with water in the spray bottle. Next loosen the cap that is installed on the pipe protruding from the wall or ceiling. Use one pipe wrench to twist the cap counterclockwise and place the other wrench on the pipe to stabilize it. It will probably take a bit of push-pull to bust the cap loose, but once it moves, stop. Spray the joint with the sudsy water.
If bubbles form, the pipe is live. If it doesn’t bubble up, turn the cap a little more and spritz it again. Repeat this process until you can remove the cap with your hand.
A word of caution here: If one pipe is abandoned, don’t assume the rest are. Repeat the sudsy water treatment with all the pipes you want to remove to make sure they’re dead.
We also suggest you go under the house and take a look at the gas line. You can trace it from the location where the line from the gas meter enters the house. If it appears old, spray each joint in a search for leaks.
Most likely your search will be negative. It’s just a little effort for a lot of peace of mind.
For you non-do-it-yourselfers, a licensed, bonded and insured plumber is the person you want for a job like this.
Your gas and electric company can also be helpful. The utility will relight pilot lights and inspect and adjust gas appliances at no charge.
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