CAZ (combustion area zone) Testing

If you have an atmospherically vented combustion appliance in your home, a CAZ test should be performed to ensure the appliance can safely function, even in the "worst-case" scenario. Because these appliances rely on the heat from the combustion gases to carry the toxic byproducts up and out the chimney (not electric fans), we like to make sure these gases are actually going to go up and out. Quite often, we find that they are spilling into the house, polluting the indoor living environment.

Should your appliance fail the CAZ test, corrective work must be completed prior to any other weatherization work taking place in the house. Notice how the water heater (photo to right) pipe insulation has melted away next to the draft hood. This is a tell-tale sign of gas spillage. Instead of going up the flue pipe, it spills out into the room, creating a fire hazard and polluting the living environment.