Combustion appliances can affect home air quality

Some appliances are potentially hazardous to your health, but combustion appliances pose particular problems. This type of equipment — which includes furnaces, water heaters, ovens, and appliances that burn oil, gas or other fuels — can produce a variety of pollutants, including carbon monoxide and particles suspended in the air.

The combustion concerns

Some of the riskier appliances are water heaters and furnaces that use atmospheric combustion by drawing air from the space around the appliance. A furnace, for example, pulls air into the combustion chamber, usually through a grill on the front, while a water heater induces air at the pilot light opening. The intake air mixes with gas to create a burn, and the exhaust is vented through the flue.

But, with water heaters, problems can arise because of the flue, which draws air in to boost the natural draft of the water heater. (Because warm air rises, combustion gases naturally rise, particularly when aided by an opening in the flue). The opening, though, also allows air to come down the flue. If the water heater is back-drafting — when exhaust gases spill into the room, instead of going out the flue — the flame may be starved for oxygen. This can cause an incomplete combustion process and result in a significantly higher level of carbon monoxide entering the home.

Reducing your exposure

All homes with fuel-burning appliances should have a carbon monoxide monitor. To reduce carbon monoxide risk at the source, use a sealed combustion furnace and direct vent, power-vented, or sealed combustion water heater, or convert from a fuel source to electricity. If you have a wood stove, open the damper when adding wood, allowing more air in to the stove, which helps the wood burn properly and blocks pollutants from being drawn back into the house. To reduce airborne particles, you can use a smart air purifier, like Airmega. While it does not affect the carbon monoxide, it can help reduce 99.97% of particulate matter.