How a Wood Stove Should Be Vented

Chimney Academy · How it works · Updated October 2026

Following the smoke: stove, connector, chimney, cap

Think of the system as a chain. Heat from the fire pushes smoke upward, and the chimney’s height and temperature create the draft that keeps it moving. EPA’s Burn Wise page calls the venting system the engine that drives the burning process. Good draft means less wood burned for the same heat, and less maintenance caused by smoldering fires.

1. The flue collar is the round or oval outlet on the stove. The pipe size at the collar sets the minimum size for what follows.
2. The connector is the stove pipe running from the collar into the chimney. It can be single-wall or double-wall, depending on the manual and the clearances.
3. The chimney is either a factory-built system listed for solid fuel, or a masonry chimney with a flue liner suited to the stove.
4. The cap and termination keep rain and animals out and set the height above the roof.

Our overview of fireplace, insert and wood stove ventilation shows how these differ from an open fireplace.

The connector pipe

The connector is where most homeowner mistakes happen because it is visible, easy to alter, and tempting to improvise. Two stove manuals show how specific the rules can be.

• Size and material. The Jøtul F 400 manual calls for 6-inch single-wall pipe of black iron or stainless steel, at least 24 gauge, or listed 6-inch double-wall pipe. Aluminum and galvanized pipe are not permitted. The Osburn manual also sets a 6-inch minimum diameter and 24-gauge steel.
• Joints. Both manuals call for at least three sheet metal screws at each joint, and each specifies which way the crimped end must face, so follow yours.
• Short and direct. Both limit elbows, advising that more than two 90-degree turns be avoided. Every turn slows the draft and gives creosote a place to collect.
• Accessible. The Jøtul manual says the connector cannot pass through an attic, roof space, closet, concealed space, floor or ceiling, and every section must be reachable for cleaning. DuraVent’s double-wall connector instructions also say not to enclose the pipe or pass it through walls, ceilings, attics or closets.

Single-wall and double-wall pipe are not interchangeable in clearance terms. Our guide on single-wall, double-wall and Class A pipe explains the differences. For one double-wall product, DuraVent lists 6 inches to walls and 8 inches to ceilings, which shows that these figures are product-specific. Never carry a number from one manual to another stove.

The rising run: why the connector should climb

Hot gas wants to rise. A connector that slopes up from the stove toward the chimney works with that tendency, while a level or downward run lets smoke stall and deposits build up. Jøtul puts a number on it: the maximum horizontal run is 3 feet, and it must rise a quarter inch per foot. Its maximum vertical run of single-wall pipe is 10 feet.

The Osburn manual takes a slightly different tack, with no stated slope figure. It recommends a minimum connector length of 4 feet and, for an exterior chimney, running the connector straight up off the stove to the highest practical point before turning horizontal.

Both approaches share the same logic. Keep horizontal sections short, lift the pipe early, and avoid long flat runs. Whether your system meets that standard depends on the numbers in your manual and on the local code.

Chimney options

The two manuals name the same two choices for the chimney itself.

• A listed factory-built chimney. Jøtul specifies a prefabricated chimney rated Type HT (2,100 degrees Fahrenheit) under UL 103. Osburn names a UL 103 HT system. Installers often call this type of insulated, double or triple-wall chimney “Class A.” It must be installed as a complete system from the manufacturer, with matching components, not mixed from different brands.
• A masonry chimney with a suitable liner. Jøtul accepts a code-approved masonry chimney with a ceramic tile or listed steel liner. Osburn requires the liner to be listed for the purpose, giving UL 1777 for US installations. Our chimney liner installation service covers relining an existing chimney.

CSIA adds a practical point about masonry flues: liners serving solid-fuel appliances need insulation, and it recommends insulating every liner that serves a wood-burning appliance. An insulated liner keeps flue gases hotter, which helps draft and slows creosote formation.

Both manuals set minimum heights, but they are not identical. Jøtul states 15 feet overall, and Osburn 12 feet from the base of the appliance. Both say the chimney must extend at least 3 feet above where it exits the roof and at least 2 feet above anything within 10 feet horizontally. Because these figures differ by stove, rely on the one for your model.

One stove, one flue

A wood stove should not share a flue with another appliance. Osburn’s manual states the rule directly: do not connect the unit to a chimney system serving another appliance. Jøtul says no other appliance may be vented into the same flue. DuraVent’s instructions likewise say all wood-burning appliances require their own separate connector pipe and chimney system.

The reasons are practical. A shared flue can pull smoke from the stove into a room served by another appliance, make draft unpredictable, and let creosote reach a second appliance. A flue serving both a fireplace and a stove is a case that needs a professional’s opinion.

Chimneys with more than one flue, such as those with a separate flue for a fireplace and another for a furnace, do not violate this rule if each appliance has its own. Confirm which flue is which with a professional before connecting anything.

Flue size and why a bigger flue is not better

The Jøtul manual requires the flue area to be no smaller than the stove’s flue collar and no more than three times its area, or twice for a masonry chimney with exposed outside walls below the roofline. In plain terms, a stove with a small collar attached to a very large old masonry flue may not draw well, because the smoke cools and slows in the oversized space. That can be a reason an older chimney is relined for a stove.

Poor draft shows up as smoke in the room when the door opens, fast creosote buildup, blackened glass, or a stove that is hard to start. Our guide on wood stove smoke when the door opens goes through those symptoms.

Get the manual, then get it inspected

Every number above comes from one manufacturer’s printed instructions. The most useful thing you can do is get the manual for your model. If you do not have it, the manufacturer’s website or a dealer can supply a copy. The certification label on the stove also gives the model.

EPA warns that installation errors by non-professionals may not be visible and may only surface as a house fire. It points readers to credentialed professionals, including the National Fireplace Institute for installers and CSIA for sweeps. The New Jersey Division of Fire Safety notes that fireplaces need local building permits and inspections, and your municipality’s code office can tell you what applies to a stove installation. Our guide on permits and contractor documents explains what paperwork to expect.

Warning signs on an existing stove include a connector that is level or sagging, pipe passing through a wall or ceiling, loose joints, rust or heavy creosote in the connector, a stove sharing a chimney with another appliance, or a missing cap. Any of these is reason to stop burning and have the setup checked.

Frequently asked questions

Related reading

• Single-wall, double-wall and Class A stove pipe
• Thimbles and connector pipes
• Clearances to combustibles around fireplaces and stoves
• Chimney liner sizing basics