Cleaning a Wood Stove and Its Pipe

Start with your stove's manual

Every stove is built a little differently. Baffles come out in different ways, catalytic combustors sit in different places, and gasket sizes and cements are model-specific. The manual that came with your stove, or the one on the manufacturer's website for your model, is the instruction sheet for everything below. Where this guide quotes a manual, it is an example of what manufacturers say, not a rule for your stove.

All of the routine tasks have one thing in common: they are done with the stove completely cold. Cast iron and steel hold heat for hours, and ash can hide live embers long after the fire looks out.

The glass

Dirty glass is a symptom first and a cleaning job second. Blaze King's owner's manual notes that the best way to keep the glass clean is to run the stove on a high burn for a while after each reload. Glass that blackens quickly usually means the fire is spending too much time burning cool, often with wet wood or the air turned down too far.

When it does need cleaning:

• Wait until the stove and glass are cool. Blaze King's manual says in capital letters not to clean the glass while it is hot.
• Use a non-abrasive cleaner. Jøtul's manual for its F 400 calls for a cleaner made for this purpose and warns that abrasives will damage the glass and leave it frosted.
• Rinse off any residue the cleaner leaves, if the manual says to, and dry it.
• Look at the glass edges and gasket while you are there. Cracked glass means the stove should not be used until the glass is replaced with the manufacturer's part.

The ash

A thin layer of ash helps a wood fire. Blaze King's manual says wood burns best on an ash bed about 1/2 inch deep and calls for removing ashes when they come within an inch of the door opening, after the stove has cooled.

Where the ash goes matters as much as when. Jøtul and Blaze King both specify a metal container with a tight-fitting lid, set on a noncombustible floor or on the ground, away from anything that can burn. Blaze King adds that hot ashes should not be stored in a garage or basement. EPA's Burn Wise guidance says the same in short form: remove ashes into a covered metal container and store it outdoors on a nonflammable surface. Our guide to ash disposal has more on this.

Door and glass gaskets

Gaskets are the woven rope seals around the door and glass. They let the stove control its air supply. A leaking gasket lets in extra air the controls cannot regulate, which can make the stove burn faster and hotter than intended, and can let smoke out when the draft is weak.

Jøtul's manual notes that door and glass gaskets harden and compress over time and should be inspected and replaced when needed. Blaze King describes a simple test: with the stove cold, close and latch the door on a strip of paper, such as a dollar bill, and pull it out; you should feel obvious resistance, and the check is repeated at several points around the door. Frayed, broken, missing or hard gasket material is due for replacement.

Replacement is often a homeowner job using the manufacturer's gasket kit and cement, done exactly as the manual describes. If the door itself is warped or the latch will not draw it tight, the problem is more than the gasket.

Firebrick, baffle and burn tubes

Above the fire in most modern non-catalytic stoves is a baffle, a plate or board that lengthens the path the hot gases take before leaving the stove. EPA's Burn Wise page on choosing stoves describes non-catalytic stoves as relying on firebox insulation, a large baffle and preheated combustion air, and notes that the baffle and some other internal parts will need replacement from time to time as they deteriorate from the heat.

Fly ash and soot collect on top of the baffle, and that is a common place for a stove to clog. Many manuals explain how to lower or remove the baffle for cleaning; some baffle boards are fragile. Inspect firebrick for cracks and crumbling, and baffles and burn tubes for warping, sagging or holes, and replace damaged parts with the manufacturer's components.

Catalytic combustors

A catalytic stove passes its smoke through a coated ceramic honeycomb where, as EPA explains, the smoke gases and particles ignite and burn. EPA notes that the combustor degrades over time and must be replaced, and that it can last more than six seasons with proper use but may fail within two years if the stove is over-fired, the wrong fuel is burned or maintenance is neglected.

Blaze King's manual describes gentle cleaning only: a soft-bristle paint brush, or a plastic vacuum wand passed near the face of the combustor, never a hard tool or brush, and only on the face of the catalyst. It also lists chemical cleaners and artificial logs among things not to burn, partly because they can damage the catalyst. If the stove starts producing visible smoke from the chimney after the combustor should be active, or the catalyst gauge stays low with a hot fire, the manual's troubleshooting section is the next step, and a worn combustor is replaced as a part.

The connector pipe and chimney

This is where creosote collects, because smoke cools as it moves away from the stove. Stove manuals ask owners to keep an eye on it during the season. Jøtul's F 400 manual calls for inspecting the chimney and connector at least every two months during the heating season and cleaning when deposits exceed 1/4 inch in any part of the system. Blaze King's manual also calls for regular inspection of the connector and chimney during the season and warns that failing to inspect and clean them can lead to a serious fire. CSIA's FAQ, summarizing NFPA 211, calls for chimneys, fireplaces and vents to be inspected at least once a year.

Looking is something an owner can do with the stove cold: some connectors have a cleanout tee or removable section, and a flashlight through the stove's flue collar, with the baffle out, may show the first part of the pipe. Taking the connector down, sweeping a liner from the roof and reassembling the system so every joint is tight are better left to a sweep. A professional stove cleaning covers the stove, connector and chimney together, with photos of what was found; see fireplace and wood stove cleaning.

When to stop and call

• Creosote that is shiny, tar-like or dripping from pipe joints.
• A roaring sound, very hot pipe, or flakes of puffed creosote after a fire, which can be signs of a chimney fire (more in the chimney fire signs guide).
• Smoke coming into the room with the door closed.
• Cracked glass, a cracked stove body, or a door that will not seal.
• Rusted, dented or separated connector pipe.

Questions homeowners ask

Sources

1. Jøtul F 400 Castine wood stove installation and operation manual (PDF)
2. Blaze King Chinook CK24 catalytic wood stove owner's manual (PDF)
3. U.S. EPA Burn Wise: Choosing the Right Wood-Burning Stove
4. U.S. EPA Burn Wise: Best Wood-Burning Practices
5. CSIA: Frequently Asked Questions

This guide is general information. It can't diagnose a specific chimney; an inspection can.