Boiler Flue Cleaning

Boiler system
  • 2-6 hours
  • Intermediate
  • 0-500
What You'll Need
Protective goggles
Protective gloves
Work overalls/disposable clothing
Protective mask
Chimney flue brushes
Extension poles
Drop cloth/tarp
Work boots
Flue cleaner

A boiler flue is the avenue that combustible gasses follow when exiting your home. Your boiler flue may very well be located within the chimney in your home or is a standalone pipe exiting through the roof. Most boiler flues are galvanized steel—these pipes vary in size. A flue cleaning twice a year is advisable. The process is much more manageable if the buildup is minimal. There are a few things to consider before attempting the cleaning of your boiler flue.

Step 1 - Measure

The boiler exhaust flue will extend from the roof or chimney. From the roof extension, measure the circumference of the flue pipe. This will tell you the size of chimney flue brush you need. Measure the height of the boiler flue pipe by measuring the building height to determine the length and number of extensions you require.

Step 2 - Inspect the Pipe

Use a powerful flashlight to look down the flue. Depending on how long the flue has gone without a cleaning some things you may see stuck to the inside of the flue are rodent or bird droppings, dead insects, or accumulated debris. This is a sure sign you need to clean the flue.

Step 3 - Purchase Supplies

man on a roof at dusk

Most of the supplies necessary to clean the boiler flue can be purchased at a local hardware store. The larger a chimney/flue brush is the more expensive. Make sure you purchase the correct size flue brush. If necessary enlist the help of a store employee to guide you to the correct equipment. If your brush is too small it will not get the job done.

Step 4 - Prepare the Work Area

Before beginning any work, turn off the power to the boiler at the circuit breaker, gas/water source. Make sure all the pipes are cooled. Protect any areas with drop cloths or plastic tarps where dust or debris may flow.

Clean the Boiler Flue

steel chimney protruding from a roof

Follow all the manufacturer's instructions for using the flue solvent. Remove or open the roof damper. Use the flashlight to get an accurate view of the inside of the flue. With the flue brush and extensions, lower the flue brush into the flue pipe, brush the inside of the pipe in a clockwise motion, then a counterclockwise motion, from the bottom up. When you have completed the brushing, close or reattach the damper. Turn the boiler and all the power back on.

Professional Cleaning

In some cases you will need to hire a professional to clean your boiler flue. In most situations the flue has a simple straight up design which allows you to follow the above instructions handily. However, some boiler flue designs may follow curves or bends that you cannot safely clean. The chimney may have more than one flue; in this case you would want to have all the flues professionally cleaned.