Gas Furnace Problems with Air in the Gas Line Symptoms

Sputtering in Furnace

• Air in the gas lines frequently results in improper combustion because the gas supply is being interrupted. As a result, the furnace may start making more noise than usual. Gas furnaces are usually fairly quiet during operation aside from the blower, but unusual popping sounds may indicate a problem with the gas flow. Louder noises such as squealing or banging are not associated with leaks or air in the lines, but they indicate a structural problem that should be inspected by a professional to prevent further damage.

Gas Smell

• If air is in the gas supply line, gas could also be escaping the line due to a breach in a gas hose or connection. Furnaces should have fail-safe devices that shut the system off if a leak is suspected, although these devices don't completely eliminate the risk. Natural gas has no smell of its own, but gas companies add a chemical to make it smell of sulfur or rotten eggs. If you detect a strong sulfur odor around the furnace or in the house, exit the home immediately and leave the door open to help ventilate the house. Call your gas company as soon as possible to investigate the cause of the odor.

Carbon Monoxide

• Air in the supply lines contributes to improper combustion, and a larger amount of carbon monoxide can result. Carbon monoxide is a natural byproduct produced in very low levels during the gas-burning process, but furnace malfunctions often cause the amount of carbon monoxide to increase. Inhalation of the gas in high doses results in lightheadedness, confusion, loss of consciousness and possible death. Install carbon monoxide detectors in your home near the furnace and near each bedroom for maximum protection, because carbon monoxide is undetectable by scent. Open all your doors and windows to ventilate the house and turn off the furnace if you suspect carbon monoxide exposure.

Hissing

• If air is entering the system through a leak, gas is also escaping, and a very small opening can allow gas to escape. The sound of gas exiting a narrow opening under pressure results frequently in a low hiss that is almost always indicative of a leak. Listen closely to the furnace whenever you inspect it, and request a professional inspection if you hear hissing that isn't normally present. Exit the house if this occurs and don't re-enter until a gas professional assures you it is safe to do so.