Posted by & filed under furnace, gas leak, maintenance.

Poorly installed, poorly maintained, and old natural gas furnaces can do more than break down and inconvenience you. They can explode. If they have a big enough natural gas leak and the gas is sufficiently concentrated, it only takes an ignition source such as a spark to cause an explosion.

When you smell gas, you must take it seriously and get yourself and your family out of the house. Call 911 and the gas company, and shut off the gas main to your house. Gas contains an odorous chemical that has a rotten egg smell. The chemical is intentionally placed in the gas to warn you of a leak.

How to Turn off Your Gas Main

Don’t wait until an emergency before learning how to shut off your gas main. Gas main shut-off valves are usually near your gas meter on a pipe that comes out of the ground. The valve will have a rectangular projection or “handle” that you can only turn with a wrench. When the handle is parallel to the pipe, the valve is open. Close the valve by using an adjustable wrench to turn the handle until it is crosswise to the pipe.

How Gas Can Leak from Your Furnace

Although gas can leak from other sources such as a gas stove or oven, your furnace is also a likely suspect. Some of the ways your furnace can leak gas include:

  • A cracked heat exchanger. Hot combustion gases from the furnace flow inside the heat exchanger, which heats fan-blown air across the heat exchanger’s outer surface. This heated air flows into and warms your home. A cracked heat exchanger allows combustion gases into the same air that warms your home. When the furnace initially starts up, unburned natural gas can enter your home through the cracked heat exchanger along with combustion gases. Note that this situation potentially exposes you to carbon monoxide as well.
  • A back drafting furnace. When furnace exhaust gases flow into your home instead of up the flue, it’s called back drafting. Back drafting can be caused by a clogged flue or by running too many exhaust fans in an airtight house. Unburned natural gas and possibly carbon monoxide will also back draft into your home.
  • A gas line or valve leak. Gas lines may corrode or their fittings can become leaky. The furnace gas valve is another potential leak source. Leaks from fittings or the gas valve may be caused by age, improper installation, or accidental damage.

The above aren’t the only reasons your furnace may leak gas. Sometimes the reasons are more complex. However, the best way to insure gas leaks never happen to your heating system is to have your furnace repair work, installation, and maintenance done by certified professionals. We’re furnace repair professionals in Schertz, TX – we’d be happy to help! Call us today at (210) 659-5801.


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