How a Wood Stove Should Be Vented

The two parts of the system

The connector (also called stovepipe or chimney connector) is the pipe from the stove's flue collar to the chimney. It is usually visible in the room.

The chimney carries the smoke the rest of the way out. It is either a factory-built chimney listed for high-temperature solid fuel use, or a masonry chimney with a liner.

The connector is not a chimney. Codes and manuals do not allow connector pipe to pass through walls, ceilings or attics as if it were one, except with listed pass-through components.

Connector pipe basics

Stove manuals set detailed connector rules. As an example, one manufacturer's manual we reviewed calls for:

• A connector diameter of at least the stove's flue collar size.
• Steel of at least 24 gauge.
• At least three sheet metal screws at each joint.
• Crimped ends pointing down, toward the stove, so condensed creosote runs back into the stove instead of leaking out of joints.

Your stove's manual may have different specifics. Follow it rather than a general rule.

Clearances to combustibles

Single-wall connector pipe radiates a lot of heat. Building codes and manufacturer instructions generally require generous clearance between single-wall connector pipe and unprotected combustible walls or ceilings. Stove manuals list their own clearances for the stove body and the connector, often with reduced distances when double-wall pipe or listed heat shields are used. Wood framing, drywall over wood studs, trim and furniture all count as combustible.

Floor protection is part of the clearance picture too. Stove manuals specify a noncombustible hearth pad of a minimum size in front of and around the stove when it sits on a combustible floor.

Chimney options

In masonry chimneys, stainless liners serving solid fuel must be insulated, according to CSIA. A liner sized to the stove gives better draft than a large old flue and reduces creosote buildup. See liner options.

One stove, one flue

Stove manuals commonly state that the stove must not be connected to a chimney that serves another appliance. Sharing a flue with a furnace or a fireplace can upset draft for both and push smoke or gases into the house. If your chimney has one flue and it already serves a boiler or furnace, the stove needs another route.

Chimney height and draft

Draft depends partly on chimney height. A widely used rule, repeated in stove manuals, is that the chimney should extend at least 3 feet above the roof where it passes through and at least 2 feet higher than any part of the roof within 10 feet. Manuals also set minimum overall heights for good draft. A chimney that is too short, or one sheltered by a taller roof section, can smoke on start-up or when the wind shifts.

Signs the venting is not working well

• Smoke rolls into the room when the stove door is opened.
• The fire is hard to start or keep going with dry wood.
• Black, tarry deposits run from connector joints.
• Heavy creosote builds up quickly between cleanings.

These are clues, not a diagnosis. Causes range from a chimney that is too short or oversized to a blocked cap, a cold exterior chimney, or a house that is short on make-up air. See why smoke comes into the room. If you see smoke in the room, stop using the stove. If a carbon monoxide alarm sounds, leave the house and call 911.

Venting a stove into a fireplace

Some homeowners want to place a stove on the hearth in front of an existing fireplace. Building codes and stove manuals generally do not accept sealing the fireplace opening and ending the connector inside the firebox. Your town's construction office can confirm what applies. Accepted methods connect the stove directly to a liner running up the flue, or to the original liner with a sealed connection. An insert, designed to sit inside the opening, is another route. See fireplace inserts explained.

Permits, inspection and upkeep

Stove manuals tell owners to check with their municipal building or fire officials about permits and requirements. In New Jersey, the chimney verification form used for replacement fuel-fired equipment includes a section for solid fuel appliances confirming the chimney is in good repair, clear, and appropriately sized. Before a new stove is installed, CSIA calls for a Level 2 inspection when an appliance is added or replaced.

Once in use, inspect often. One stove manual calls for checking for creosote at least every two months during the heating season. Annual inspection and cleaning as needed follow NFPA 211 as summarized by CSIA.

Next step

Planning a stove or rethinking an old installation? Request an assessment. See our wood stove installation and service and chimney liners pages.

Questions homeowners ask

Sources

1. Osburn 1800 wood stove installation and owner's manual
2. CSIA: Homeowner Resources and FAQ
3. CSIA: The Three Levels of Chimney Inspections
4. NJ DCA Form F370: Chimney Verification for Replacement of Fuel-Fired Equipment
5. US EPA Burn Wise: Choosing Wood-Burning Appliances

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