Small wood stoves have increased in popularity over the last few years, but flue parts in smaller sizes remain difficult to find.
In this article, we'll cover the North American vendors for small size chimney systems, options for adapting to larger chimney systems, and basics for safe flue system design.
tl;dr: skip to 3" Flue, 4" Flue, 5" Flue, 6" Flue
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Building Codes and Tiny Stove Flue Systems
If your installation is going to be subject to building codes, you will most likely need to use UL Listed Class A chimney pipe. Specifically, wood stove chimney systems should be certified to the standard UL 103-HT.
Some of the vendors listed in this article offer pipe that is not UL Listed. Since structures like RVs, buses, vans, and Tiny Homes on Wheels don't tend to be subject to building codes, unlisted pipe isn't necessarily a problem.
But if you need to pass inspection, or if your insurance company requires it, you may need to use more expensive UL listed pipe, or adapt your stove to a larger size.
Using a 5" or 6" Chimney with a Small Wood Stove
Increasing the size of your flue system will generally have a negative effect on your stove's draft. However, if you're replacing a larger stove, you can save a lot of money by using the existing flue system. And if you're installing a small stove in a structure subject to building codes, you may not be allowed to use the smaller unlisted sizes.
As long as your flue system is well designed, you can generally connect:
- 3" stove to a 4" or 5" roof exit
- 4" stove to a 5" or 6" roof exit, or a 5" wall exit
- 5" stove to a 6" or 8" roof exit, or a 6" wall exit
Learn more about connecting a small stove to a larger flue system.
3" Flue Systems
Tiny Wood Stove
Tiny Wood Stove carries complete flue systems in 3 inch, including Tiny House and RV/Bus roof exit kits, single-wall and insulated Class A pipe, elbows for offsets, and tees for rear exits. Try their Flue System Builder to build your complete flue system.
Cubic Mini
Cubic Mini carries 3 inch flue parts that match their Grizzly and Cub stoves, which use a flue size slightly smaller than a standard 3 inch. Since Cubic Mini doesn't recommend any elbows or wall exits, they only offer straight roof exit options.
It's possible to adapt the Cubic Mini pipe to standard 3 inch stoves with top exits, but you'll need to cut the outer wall off the bottom of the pipe and use some stove cement to fill in the gap inside of the flue flange.
Dickinson Marine
Dickinson Marine offers complete 3 inch flue systems in stainless single-wall only including a marine style through-the-deck fitting.
4" Flue Systems
Tiny Wood Stove
Tiny Wood Stove carries complete flue systems in 4 inch including roof exits, wall exits, specific kits for RVs/Buses, Tiny Houses, and Yurts, single-wall and insulated Class A pipe, elbows for offsets, and tees for rear exits. Try their Flue System Builder to build your complete flue system.
509 Stoves
509 Stoves in Post Falls, Idaho offers 4 inch UL listed (UL103-HT) insulated chimney pipe to support their new "Mini Me" stove line. This is the only place we're aware of in North America offering UL Listed Class A pipe in 4 inch.
Dickinson Marine
Dickinson Marine offers complete 4 inch flue systems in stainless single-wall only including a marine style through-the-deck fitting.
Navigator Stove Works
Navigator Stove Works offers complete 4 inch flue systems, but only to support Navigator stoves. If you're installing a Sardine, Cod, or Halibut stove, you can get your flue parts through Navigator
SmallWoodStoves.com
SmallWoodStoves.com offers a selection of 4" single-wall and 4" double-wall insulated Class A chimney components in 4", including 15-, 30-, and 45-degree double-wall insulated elbows.
5" Flue Systems
Tiny Wood Stove
Tiny Wood Stove carries complete flue systems in 5 inch including roof exits, wall exits, specific kits for RVs/Buses, Tiny Houses, and Yurts, single-wall and insulated Class A pipe, elbows for offsets, and tees for rear exits. Try their Flue System Builder to build your complete flue system.
If you need UL Listed Class A chimney pipe for a code compliant installation, Tiny Wood Stove also carries 5 inch Ventis Chimney Systems, which are certified UL 103-HT. They also carry adapters to connect to 5 inch flue systems to smaller stoves.
Northline Express
Northline Express carries two brands of 5 inch UL Listed (UL 103-HT) chimney systems suitable for wood stoves. Selkirk SuperPro, available in various lengths, with elbows and accessories appropriate for a roof or wall exit. DuraTech class A pipe (also UL 103-HT certified) is also available with similar options.
Dickinson Marine
Dickinson Marine offers complete 5 inch flue systems in stainless single-wall only including a marine style through-the-deck fitting.
6" Flue Systems
Amazon
Amazon.com offers several UL-103HT Certified chimney systems. Products are available from Rainbow Chimney, Ecovent USA, and Duravent, individually or in kits.
Northline Express
Northline Express offers UL 103-HT certified DuraTech Shasta Vent, and Selkirk chimney systems in 6 inch. Try their automated chimney pipe system builder to build your complete flue system.
How to Build a Safe Wood Stove Flue System
A properly installed and maintained wood stove is a very safe appliance. However, using the wrong materials or assembling them incorrectly can be a dangerous fire hazard. In addition to following the instructions that come with your stove, a few design considerations will ensure a safe installation.
For more information on safe installation, see the industry standard for residential wood stoves, NFPA-211.
Proper Materials
Your flue system should be labeled for use with solid fuel or "multi-fuel" stoves. Don't use pellet pipe, B-vent, or galvanized furnace or dryer vent, since those products not rated to withstand the temperatures a wood stove will produce.
Single-wall and non-insulated double-wall pipe can be used as connector pipe between the stove and the chimney system, but you should use Class A pipe to penetrate your ceiling/roof or wall, and for everything outside. Class A pipe is either double-wall with insulation between the layers, or air-cooled triple wall pipe.
Safe Clearances
Since stovepipe gets hot during normal operation, you must provide adequate clearances between the pipe and any combustible materials. This is especially true where the pipe passes through your roof or wall, since you won't be able to see a problem until it's too late.
In general, Class A pipe requires 2" clearance to combustibles, double-wall connector pipe requires 9" clearance, and single-wall pipe requires 18" clearance. Some pipes have different rated clearances, and you can sometimes reduce safe clearances with heat shields, so consult your stove or flue system manual for information on proper installation.
Good Chimney Design
Natural draft wood stoves need a properly designed flue system, or they won't function. The rising smoke in the chimney creates a "draft," which pulls air through the stove's intakes, and smoke out through the flue collar. If your chimney is poorly designed, your stove may leak smoke into your living space.
Height Above the Roof
Sufficient chimney height above the roof is a helpful for a few reasons:
- Keeping the chimney opening away from the roof can prevent creosote from condensing on the roof. Creosote is messy, and in severe cases could be ignited by sparks from the chimney.
- A sufficiently tall chimney helps prevent backdrafts. Wind passing over a structure can push down on a too-short chimney, causing smoke to back up into the living space. If the chimney is tall enough, any wind should hit it laterally instead of downward.
- A taller chimney increases the overall height of the flue system, which tends to create a stronger draft.
For stick built tiny homes, you generally want to follow the 3-2-10 rule. The chimney opening should be 3 feet above the point where the pipe passes the roof line, or 2 feet above the highest point within 10 feet, whichever is higher.
There's currently no industry standard for chimney height above the roof for RVs, buses, and vans. Chimneys on boats need only terminate above the deck. On these structures, shorter, stubby chimneys are sometimes used. However, for ideal draft in less than ideal conditions, having a detachable chimney option for extra height is ideal. Learn more about building a detachable chimney.
Side wall vents, where the chimney terminates horizontally through a wall below the roof line, are never allowed for wood stoves. Even if it was able to produce enough draft to drive the stove, a side wall vent would cover the side of the structure in creosote, and would back-draft any time wind blew against that side of the structure.
Overall Height
In general, the taller your chimney, the stronger the draft. Most household stoves expect to have 15 feet or more of height between the fire and the chimney opening.
Most tiny structures aren't tall enough to support 15 feet of chimney, and that's OK. Small stoves can function well with shorter chimneys. But the shorter the chimney, the weaker the draft. If you have an especially short structure, check with the stove manufacturer about the minimum chimney height for your stove to ensure it will draft reliably.
Straight and Vertical
A straight roof exit will draft better than any other flue configuration, though it's not always possible. Sometimes a couple of 45 degree elbows or a wall exit is the best option for a flue system.
Less than ideal configurations can work well. But keep your flue system as straight and vertical as possible to ensure strong draft.
