When the heating maintenance technician makes an annual service call, they clean, service, and check your gas furnace to protect both the equipment and your family. Two important things your technician may check are the combustion gasses and flue draft. The results of these tests let the technician know if your furnace needs repairs. Here's how these tests are done.

1. Draft Check

The draft check is done using a gauge that measures pressure. When the measurement is in the right range, it lets the technician know combustion gases can flow out the flue and escape your house properly. If the reading is abnormal, the technician is alerted to a potentially dangerous situation. The combustion gases may not get pulled out of the flue, but they might collect in the furnace or leak out in your house instead.

Once the technician knows the flue isn't working properly, they have to pinpoint the cause. The problem might be something like a bird's nest in the flue that's causing a blockage. The problem might also be due to a vent fan elsewhere in the home that's interfering with the normal gas flow through the flue. The problem has to be tracked down to eliminate the risk of carbon monoxide being released into your home.

2. Combustion Gas Analysis 

A gas analysis is done with a meter that gives digital readings of carbon monoxide level, oxygen level, and temperature. If readings are in the right range, the technician knows there are no problems with the heat exchanger in the furnace and that combustion is working as it should.

If abnormal readings are found, they could indicate a crack in the heat exchanger that's letting carbon monoxide escape. If you have a carbon monoxide monitor near your furnace, it picks up on larger amounts of the gas when it's leaking out. A gas analysis meter is much more sensitive, and it can pick up on problems before they become serious.

Both of these tests are quick and easy to do as part of an annual heating maintenance check. Knowing the results of the tests gives you peace of mind your gas furnace is working properly and that there are no hidden problems with combustion gasses.

However, if one of these tests shows a potential problem with your furnace, the technician can make repairs or schedule them for later so your family will be safe and your furnace will be in good shape when it has to run every day during the winter.