The lingering odor of sewage is NEVER a good sign for your heating system! As you can guess, locating the source as soon as possible is essential in avoiding hazardous health concerns and dangerous toxins! Sewer gas contains methane, which can make it explosive if enough is gathered in an area.
As the source of the odor is sewer gas, it’s a no-brainer that it’s coming from your septic tank or sewer system. Sewage gas can get into your home through pipes, especially when a p-trap under a sink, tub or toilet is dry. A p-trap can dry out if there is a long period of non-use. When a heater is blowing sewer odor through the vents, a few scenarios can point out the cause and effect.
Air Intake Nearby
Air is pulled through an intake when the heater turns on; it’s typically where the air filter is installed. This air is heated and the fans circulate the air through the ducts to the vents. But if you have a dry p-trap near the central heat intake, the odor could be sucked in as well. The filter only handles dirt and debris; it won’t do anything for the smell. Unfortunately, the sewer odor will be circulated throughout the house.
Often times, the ductwork for your heating system and plumbing pipes are installed beneath the floors. With a rupture or leak in a main sewer or septic line, the odor will spread underneath the house. The septic tank can be located near an air vent and with the addition of a duct leak, the odor will nonetheless get into your home.
A/C Condensate Lines
If the sewer odor is coming from the condensate drain line in your outside heating unit, this signifies that the condensate drain line could have been tied into your home’s main drainage line. If the line is not properly vented or trapped, the gas from the sewer or septic tank can travel back to the A/C unit and pumped into the duct system. A trap will need to be installed on the line to prevent this from occurring.