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Combustion spillage is a term used to describe the unwanted flow of combustion gases into your home. The quantities involved are usually small; however, combustion spillage is a serious health hazard and should be dealt with as soon as possible.

If your home has any of these combustion appliances you may have risk of combustion spillage:

  • Gas-fired furnace, boiler, or water heater
  • Oil-fired furnace, boiler or water heater
  • Wood stove or fireplace
  • Portable propane, natural gas or kerosene heaters
  • Other fuel-burning devices (e.g. gas range)

Normally, these combustion products – which can include both visible smoke and various invisible gases – are vented to the outdoors through a chimney or vent pipe. Unfortunately, in some circumstances they may instead escape into your home, which can cause a variety of health concerns.

How is combustion spillage tested?

If you have any of the combustion appliances mentioned above, an exhaust devices depressurization test (also known as a combustion spillage test) can be performed to test your risk for combustion spillage. The test can be performed by an energy advisor,and involves running all of the exhaust fans to test  whether combustion gases can be pulled into your home by the exhaust systems. This test is a routine part of every EnerGuide home evaluation for homes with combustion appliances. If you are at risk, the energy advisor will let you know, and provide guidance on who you can contact to address the problem.

Please note, if a building inspector requests a combustion spillage test after you’ve completed a kitchen upgrade, you will need to have a combustion spillage test performed by a professional with heating, ventilation, and air conditioning (HVAC) or Thermal Environmental Comfort Association (TECA) certification. Not all energy advisors are qualified to perform this specific combustion spillage test, unless they have HVAC and TECA certifications.

For more information about combustion spillage, its causes and how to prevent it, visit Natural Resources Canada.

Did you see a building science or energy efficiency term you did not understand? Check out our glossary.