I recently purchased a home and once utilities were turned on I've been having issues with certain gas appliances. Some appliances required a normal amount of time to get the gas flowing after being off for some time. One water heater was finally able to light, as well as one furnace and the stove. However, a second water heater, second furnace, and the gas-log fireplace will not light. The individual gas valves to each appliance are in the on position but I never smell any gas. Is it possible for there to be restrictions in the gas supply lines that would affect all of these appliances? How can I troubleshoot this issue?

  • Is this a single family home or a converted 2 unit apartment? You won't smell gas from the water heater or furnace but you should from the fireplace. There may be an additional valve somewhere that you need to open. Commented Mar 28, 2019 at 19:23
  • Are these older appliances that use pilot lights or newer ones that have igniters? Older versions with pilot lights will not allow gas to flow until the pilot light is lit and it can heat up the thermocouple.
    – JRaef
    Commented Mar 28, 2019 at 19:29

2 Answers 2


It sounds like the gas system was never purged after a nitrogen test. The appliances in question are probably farther down the line and still have non-combustables in them. It will take a very long time to purge through a pilot tube. You need to close the gas line valve on one of the appliances, remove the drip leg, open the valve to vent non-combustables and close it when the sound changes or you smell gas. Replace the drip leg, open the valve and start the appliance.

Do not do this alone. Someone needs to be with you in case you pass out, have a stroke, faint etc. It's very unlikely but if you are rendered incapable of closing the valve a second person can. This is important. Explosions happen because of this.


There may be other valves in the piping. When my house was built , they forgot to run gas for the dryer ( It also had an electric supply). They added a valve in the attic for the pipe run to the dryer. Later , I added another valve in the attic for gas line to a outside grill.

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