air test - gas lines leaking

[Robert D.]

I have a 3br single family with no basement. The gas lines are leaking somewhere. I need to connect compressor and do the air pressure test. The furnace and water heater is connected. Where would be an ideal place to connect the compressor ? outside, by the water heater etc ? and what size of compressor I need. Would 5-6 gallon compressor be enough ? are there any no-no’s while doing the job ? I definitely do not want to damage the lines pumping to much air.

[Paul Sandhu]

Do it yourself.  It is easy peasy.  First you will need a $10 pressure gauge that will screw right on to your gas pipe.  It also will have a nipple on it exactly like an automobile tire, to put pressure in the system.  Any hardware store will have it.  

1. Shut off gas supply.  Disconnect the gas outlet line from the meter and plug it.  When there is excess pressure from the house side of the gas meter, the meter will vent off the gas.

2. Attach your gauge that you bought from the first paragraph.  I usually disconnect my water heater or stove, then attach the gauge to the gas line.  

3. Shut the supply valve off to every gas appliance you have.  Each appliance should have its own valve.  90 degree turn should be all it needs.

4. Use an air compressor and bring it up to 10 psi.  Normal pressure is 3 or 4 ounces per square inch.  In this state, a house has to hold 10 psi for 10 minutes to pass the inspection.  A business is 15 psi for 15 minutes.

5. Windex or soapy water in a spray bottle.  Spray every joint, fitting, valve, connection, etc in the system.  I have also seen old pipes that had pinhole cracks in them from rust.  You will see bubbles where it is leaking.

6. If there is no leak, open up a supply valve to an appliance and check the line that just got pressure.  Repeat.