Furnace Clean Out Door

The clean outdoor is designed to allow homeowners to remove ash from fireplaces at the exterior side of a wood-burning masonry fireplace. During the chimney sweep and cleaning process, our technicians DO NOT CLEAN or empty this debris-filled cavity.

This is the responsibility of the homeowner. What our cleaning process entails is the cleaning of the chimney liner, smoke chamber, damper shelf, and firebox debris. The material we remove during our cleaning is creosote which is highly flammable and is a fire hazard. The ash in the ash dump is burnt ash which is not flammable. Most chimney sweeps as a general practice do not clean these ash dumps. We only clean upon request and may be at an additional cost.

The clean out door for a furnace is designed to allow a chimney sweep to sweep the flue and remove the creosote deposits after cleaning. The furnace clean out for a furnace is always cleaned during service and is required by IRC building codes.

Both look alike but are two different uses.

Homes with masonry chimneys can have two doors near the base of the chimney that look very similar:

• Fireplace ash pit clean out. Below a fireplace with an ash dump door, this door lets you remove the ashes that were swept into the ash pit. Emptying it is normally the homeowner’s job.
• Flue clean out. At the bottom of a flue that serves a furnace, boiler, or wood stove, this door lets a chimney sweep remove the soot, creosote, and debris that fall to the base of the flue during cleaning. We clean this out whenever we service that flue.

If you’re not sure which door is which, we’ll show you during your visit.

When a flue is swept, the deposits brushed off the walls fall to the bottom. Debris also comes from a deteriorating liner, loose mortar, nesting material, or a damaged cap. If it builds up, it can reach the opening where the appliance connects to the chimney and block the exhaust path, which can force smoke and carbon monoxide back into the home. That’s why building codes generally call for a clean out opening near the base of each masonry flue.

• The door is rusted, bent, or won’t close tightly
• The door is missing or has been covered over
• Cold drafts, soot smells, or soot stains around the door
• A pile of debris at the base of the flue
• Water or rust at the bottom of the flue, which can point to a missing cap or a leak higher up

A clean out door that doesn’t close tightly lets air leak into the flue, which can weaken the draft for the appliance that flue serves.

During a sweep, we open the clean out, remove the debris, and look at what has collected. Large pieces of clay tile, mortar, or nesting material tell us something is wrong higher up. If the door or frame is damaged, we replace it with a tight-fitting metal door set in mortar. When the debris points to a flue problem, we check the liner and the top of the chimney, including the cap and the top flue tile.

• Keep the clean out door closed except when the flue is being serviced.
• Don’t store anything that can burn right next to the door.
• If you use your ash dump, empty the ash pit regularly and put the ashes in a covered metal container outdoors.
• If you find pieces of clay tile or an unusual amount of debris at the bottom, schedule a chimney inspection.