Is It Important to Clean a Furnace Flue?

Though you likely don’t run your furnace too often, it’s still important to have your furnace flue cleaned and inspected from time to time. The flue allows potentially deadly combustion gases to escape your home safely, and if it is dirty or in disrepair, it may not be able to do this effectively. Here’s everything you need to know about the furnace flue.

Parts of a Furnace Flue

The flue itself is a pipe that runs from your furnace’s air handler through your roof. It’s much like a chimney on a fireplace in that it’s designed to allow combustion gases to escape safely. Inside the flue is a damper, which is a valve that opens and closes as needed to allow gases to escape. When your furnace kicks on, the damper opens. When the furnace isn’t running, the damper closes to keep out rain and other debris. Finally, there’s a flue cap on the portion of the flue that comes out of your roof. This is another feature designed to keep animals, moisture, and debris out of the flue itself.

Does It Matter Which Kind of Fuel I Use?

It’s vital to have your furnace flue cleaned and inspected regularly regardless of the fuel you use. Natural gas, oil, and LP gas all create combustion gases like carbon monoxide as they burn. The exception to this is an electric furnace; these do not require any ventilation as they produce heat that is safe and free from gases. It’s much like using electric heat strips, which do not require flue pipes.

Common Furnace Flue Problems

The most common issues with furnace flues are as follows:

  • Blockages – Debris falling into the flue from above, animal nests, or built-up soot can all block the flue pipe, which prevents dangerous gases from escaping.
  • Roof leaks – The flashing around the area where the flue comes through the roof may leak at some point.
  • Corrosion – If you live in an area prone to acid rainfall, the metal may corrode over time. This may hinder the proper operation of the flue cap.
  • Malfunctioning dampers – In some cases, the dampers installed inside the flue pipe may fail to open or close. Most newer furnaces have safety mechanisms built in that prevent the furnace from igniting in such a case.
  • Incorrect size – If your furnace is due for replacement, or if it has already been replaced, it’s vital to ensure that your furnace flue is the right size for your new furnace.

When to Schedule an Appointment

You should have your furnace flue inspected annually, even if you didn’t run your furnace all year. This is because the flue could be corroded or leaking, which can cause damage. You should also call for service if your carbon monoxide detector signals unusually high levels of CO2 at any point; this may indicate an issue with dampers, or it may mean your flue is not the proper size for your furnace.

Although you probably don’t use your furnace much thanks to the mild climate during the winter months, it’s still important to have the furnace flue inspected and serviced each year. This way, if you need to keep warm during a cold snap, you’ll be safe and comfortable.

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