Check Your Furnace Flue Each Heating Season
In the icy cold winters of the Chicago area, your furnace is indispensable, burning gas or oil to keep your home comfortable. During this combustion process, dangerous gases are produced, such as sulfur dioxide, nitrogen dioxide, and carbon monoxide. These gases must be vented outside to keep your home safe.
This is the job of the flue, a large metal pipe that extends from the furnace to a chimney liner or an independent flue pipe. This pipe brings combustion gases safely through your home and up through the roof, expelling them above the roof line. Any blockages, leaks, or damage to the flue could allow combustion gases to enter your home, with dangerous or even deadly health consequences.
What Causes Flue Problems?
Combustion gases can enter your home from the flue when there is a leak in the pipe, a blockage due to a foreign object, or when backdrafting occurs. Backdrafting happens when the furnace cannot draw sufficient air from the interior of your home to fuel the combustion process, and instead must draw it through the flue itself, carrying the combustion gases with it. Flue problems can occur due to:
- Corrosion – Combustion gases contain significant amounts of moisture and acidic compounds, which can corrode the steel flue pipe over time, creating leaks.
- Loose joints – Loose joints can occur as the flue expands and contracts with temperature changes over time, causing leaks.
- Damaged flue pipe – If the flue pipe is damaged due to an accident or poor installation, it can restrict airflow and cause backdrafting.
- Insufficient airflow – If your furnace cannot access enough air for combustion it will backdraft. This can be due to a powerful exhaust fan creating negative pressure, too many fuel-burning appliances in a small mechanical room, or an HVAC system that is not properly balanced, creating negative pressure that draws combustion gases inside.
- Chimney damage – If your flue connects to a chimney liner or runs through the existing chimney, things like broken tiles, bricks, or other debris can fall into the flue and block it.
- Missing flue cap – If the cap is missing where the flue pipe exits the roof, debris can fall into the flue, or animals like birds can build nests in the pipe during the summer.
How To Find Your Furnace Flue
The furnace flue will usually be located on the top or the rear of the furnace, and it will be connected directly to a chimney or to a metal flue pipe that extends vertically to the roof. Most of the remaining pipe will be hidden as it passes through your home, though it may be visible in the attic.
How To Check Your Furnace Flue
As a homeowner, checking your flue pipe consists mainly of a visual inspection. Before each heating season, check the flue pipe for signs of damage, such as:
- Loose joints
- Water stains or white streaks
- Sooty deposits on the pipe or furnace
From the ground, you may also be able to spot a missing flue cap or chimney damage. For a thorough flue inspection, however, it is best to call a professional HVAC service. They can make sure the flue is in good condition, free of blockages, and drafting properly.
Furnace Maintenance in Chicagoland
As part of our furnace maintenance services, our expert technicians at ABC Plumbing, Sewer, Heating, Cooling and Electric can provide a full flue inspection, including checking the condition of the pipe, measuring flue gases, and more.
Call 888-868-6667 or contact us online to schedule furnace maintenance in Chicago!
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