Stove Pipe Elbows: Which Angle and Size You Need

In short: Match the elbow to your flue collar diameter, 6 inch or 8 inch, then pick 45 degrees to step around an obstruction and 90 degrees to turn flat into a wall.

Almost nobody plans to put a bend in a flue. You set the stove where you want it, look up, and there is a rafter, a purlin or a window head exactly where the pipe wants to go. That is when an elbow stops being an accessory and becomes the part that decides whether the install works. Get the angle and the diameter right and the job is an afternoon. Get them wrong and you are back at the counter.

Can you put an elbow in a wood stove pipe?

Yes. A bend in the connector pipe, the run between the stove and the chimney, is normal and every manufacturer supplies fittings for it. What you cannot do is bend the pipe itself or improvise a joint. You use a listed elbow made for that pipe, in the same diameter and the same wall type, and you keep the number of bends down. Each turn costs you a little draft, because smoke climbs a straight vertical flue better than a stepped one.

The types of elbow, and which angle to choose

Stove flues use four elbow angles: 15, 30, 45 and 90 degrees. The first two come as Class A offset kits for the insulated chimney above the ceiling; 45 and 90 degree fittings are the connector elbows you use in the room, in single wall or double wall to match your pipe. The angle follows what you are getting around. A 45 degree pair steps the pipe sideways and keeps it climbing, which protects your draft. A single 90 degree elbow turns the run flat into a wall, which is what a through the wall install needs. If you have a choice, choose the shallower angle.

• 45 degrees, used in pairs: shifts the flue sideways past a rafter or a ridge beam while the pipe keeps rising. The gentlest option for draft.
• 90 degrees, used singly: takes the connector horizontally into a wall thimble on a through the wall system.
• 15 and 30 degrees, on Class A pipe: supplied as offset kits for the insulated chimney above the ceiling, not for the connector in the room.

People often ask about the four classifications of pipe elbows. That taxonomy comes from industrial plumbing and it does not map onto a stove flue. Here the four things that actually decide which part you order are the angle, the wall type, the diameter, and whether the fitting is for connector pipe or for Class A chimney.

What size elbow do I need?

To know which elbow size you need, read one number: the diameter of the flue collar on your wood-burning stove. The elbow matches the pipe, and the pipe matches your stove. Read the diameter of the flue collar on the back or top of the appliance, and buy that size the whole way up. A 6 inch stove takes 6 inch pipe and 6 inch elbows. Reducing the diameter to squeeze past an obstruction chokes the draft and is not a repair for a clearance problem.

One compatibility point worth checking before you order: our connector elbows are made to fit our own pipe and are not listed as compatible with other chimney pipe brands. To know whether a fitting suits your existing setup, check two things: that the diameter matches, 6 inch or 8 inch, and that the rest of the run is our pipe. If half your system is already up and came from somewhere else, measure the actual crimp and call us on 888-834-0880 before you buy. We do not recommend specific competing brands; the safe rule is to stay with the system you already own, because listed fittings are tested as part of one manufacturer's assembly and not across brands.

Single-wall and double-wall elbows are not interchangeable

They look similar and they carry very different clearances, so this is the one place where guessing gets expensive.

Per NFPA 211, single-wall stove pipe (the connector pipe inside the room between the appliance and the Class A chimney) must maintain at least 18 inches of clearance from any combustible wall, ceiling, or framing.

Per NFPA 211, double-wall stove pipe is rated for reduced clearances typically 6 inches from combustible walls and 8 inches from ceilings (verify exact clearance with the specific UL-listed product).

There is no separate heat shield for elbows in our range: on a connector run the listed way to cut clearance is double wall pipe, not a shield added to single wall. So if the reason you need a bend is that a combustible surface is close, a double wall elbow may solve the problem that a single wall elbow created. Our double wall elbows carry a UL 103 HT listing; the single wall connector elbows are listed to ULC S641.

What stove pipe elbows cost

A single wall connector elbow costs between $65 and $84 depending on diameter and angle, and the 6 inch double wall 90 degree elbow is $133. Class A insulated offset kits are a different class of part and start at $417. Prices below are the live US store prices for the fittings themselves.

The gap between a connector elbow and a Class A elbow kit is not a markup. A connector elbow is a single black fitting for the room. A Class A kit is insulated chimney, built to run through a structure and hold a 1000°F (538°C) continuous rating, and it is sold as a kit rather than as a single fitting.

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How many elbows can you use?

Use the fewest bends the installation allows. Every elbow adds resistance and another place where deposits can collect. The permitted layout depends on the stove, connector system and manufacturer's installation instructions. If the route requires multiple offsets, have the proposed layout checked before ordering rather than assuming another fitting can be added safely.

For a bend in the insulated chimney above the ceiling, the measuring and the limits are set out in our guide on how to measure the offset for a chimney pipe, which covers rise, connector length and the offset chart for the 15 and 30 degree kits.

Not sure how many turns your layout really needs? Send us your measurements and we will put a flue design together for you at no charge through our Expert Advice service.

Does a bend change the chimney height rules?

The height rules govern where the chimney finishes, not where the connector bends, and an offset lower down does not relax them. What an offset does change is the geometry they are measured against: if your bend moves the chimney sideways to clear an eave, the clearance to nearby roof structure has to be measured again from the new position. Our page on chimney pipe building codes sets out the termination requirement in full, and our guide on how tall a chimney needs to be works through the measurement.

Installing an elbow correctly

The single detail people get backwards is the direction of the joint. Connector pipe assembles with the crimped end pointing down toward the stove, so any condensate or creosote that forms inside runs back into the appliance instead of seeping out of a seam onto your floor. An elbow follows the same logic as the straight sections around it.

• Dry fit the whole run before fastening anything, including the elbow, so you can still turn a section.
• Fasten each joint with sheet metal screws as the instructions supplied with the pipe specify.
• Support the weight. An offset in a vertical run pulls sideways, and an elbow strap ties it back to structure so the joint below is not carrying the load.
• Recheck clearance after the bend, not just before it. The pipe is in a new place now.
• Keep the bend reachable. None of our connector elbows include a cleanout door, so leave yourself room to get a brush in.

Our cover runs on the instructions, not on who holds the screwdriver. The limited warranty applies when the product is installed in accordance with the instructions supplied with it, whether you fit it yourself or a contractor does, and the terms for each product class are set out on our warranty page.

What are stove pipe elbows made from?

Connector elbows are black finished steel stove pipe fittings, listed to ULC S641, which is the standard for the pipe between a solid fuel appliance and the chimney. The double wall version is listed to UL 103 HT and carries a second skin with an air gap, which is what buys the reduced clearance. Class A offset kits are insulated chimney sections listed to UL 103 HT and rated for 1000°F (538°C) continuous use.

Common elbow problems, and how often to check

Elbows fail in four predictable ways, and all four are visible from the floor with a flashlight.

• Creosote build-up on the outside of the turn, where the gas slows down. A hard shiny glaze means the flue is running too cool.
• A sagging offset, where nothing carries the sideways load and the joint below the bend has crept open.
• A joint fitted the wrong way round, which lets condensate weep out of the seam and stain the pipe below it.
• Rust or a soft patch in the steel, usually at the low point of the bend, which means the fitting is done and should be replaced rather than patched.

Check the elbows every time the flue is swept, and at least once at the start of each heating season. A connector elbow that is clean, sound and firmly strapped stays in service; one that has gone soft or perforated is replaced, not repaired.

Can I use one on a fireplace?

Not in the same way. Connector elbows are made for a freestanding stove or an insert that vents into a chimney. An open masonry fireplace being brought back into service is a lining job, and the right part is a chimney liner kit sized to the appliance rather than a stove pipe elbow.

Cleaning and checking the bends

Elbows are where a flue tells you how it is doing. Creosote gathers on the outside of a turn, so when you sweep, brush through the bend rather than past it and look at what comes down. Soft brown flakes are normal deposit. A hard shiny black glaze means the flue is running too cool or too slow, and a bend too many is one of the reasons that happens. Check the elbow strap and the screws at the same visit, because a joint that has crept open is easier to see with the pipe cold and the stove out.

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Need more information?

• Frequently asked questions
• Wood stove pipe installation guides
• Free flue design service through our Expert Advice team

Or call the team on 888-834-0880, 9am to 9pm, seven days a week.