Once the fire heats the water in your boiler, the excess gases have to go somewhere and that somewhere is up your boiler's flue. Only coal, wood or pellet boiler flues need cleaning, since they build up ash and creosote over years of use. A dirty boiler flue is a fire hazard and keeps the smoke from exiting your house properly. Clean your boiler flue at least once a year before winter.
Turn off the power on your boiler and place sheets around the boiler and on the floor around it.
Put on the gloves, face mask and goggles and climb the ladder to your boiler's flue. Remove the flue cap.
Push the flue brush into the flue and extend it all the way until it reaches the boiler's firebox. Scrub the inside of your boiler's flue with the flue brush by pulling the brush up and down. Start at the bottom of the flue and work up.
Remove the brush from the flue and place the cap back on the flue. Climb down the ladder.
Remove the tarps from the boiler and take up the boiler's ash pan. Dispose of the ash and other debris by burying it.