Installing a wood-burning stove isn’t too difficult. Many homeowners DIY the entire process with great success. Unfortunately, not the venting part. Whether for a wood-burning or gas stove, venting stoves is a complex process, further compounded by the inherent safety risks. It takes just one misstep to put the entire house under a fire hazard.
We’ve prepared this guide to help you learn everything you need to know about wood stove venting, so you’re prepared when duty calls.
Let’s begin with the obvious – a definition. Furnace venting refers to the process of creating a path for exhaust fumes from your wood stove (or any other fossil fuel heating system) to exit the stove or furnace.
The term “venting” also refers to the structure through which exhaust gases exit the stove or furnace. Of note is that venting systems can address only the exit of exhaust fumes or both the exhaust process and air inlet process.
Can You Vent a Wood Burning Stove Through the Wall?
Yes, you can vent wood-burning stoves through the wall. However, it’s not recommended given the many challenges wall venting presents. The main reason roof venting works best for wood stoves and other low-efficiency fossil fuel heating systems is that it reduces backdrafts and odors in the home. Why? Because roof installation complements the stack effect.
The stack effect refers to the property of warm air inside buildings to rise to the ceiling due to buoyancy. This usually creates a neutral pressure plane when the pressure inside the house equals the pressure outside.
Roof venting takes advantage of the stack effect to force hot exhaust fumes outside the house. Moreover, since the exhaust pipe, if installed to code, is taller than your home, the exhaust gases will dissipate into the outside atmosphere without backdraft unless it encounters strong winds.
Unfortunately, wall vent systems attempt to ignore the stack effect. By venting your stove below the roof level, you’re asking for stack effect resistance that often results in a strong backdraft.
The backdraft of exhaust gases into your home is a safety hazard and can also cause foul odors in the home. Even worse, wall venting can result in a cold hearth, resulting in less efficient wood-burning.
For the above reasons, wall venting is considered a last resort for wood stove installations. You should only consider it when faced with structural limitations.
Choosing Pipe Type for Wood Stove Wall Venting
So, we will assume that you have no otherwise but to install your wood stove vent through the wall. In that case, the first step is to choose a suitable pipe. You need to prioritize two things;
Double vs. Single-Walled Wood Stove Pipe
Choosing between double and single-walled woodstove pipes shouldn’t be too big a problem. However, you first need to know the main difference between the two. As the name suggests, double-walled stovepipes have two walls, while the single-wall pipe only has one wall. The extra wall creates a ¼ inch airspace between the inner and outer walls, vastly enhancing insulation.
Additionally, double-walled vent pipes are better than their single-walled counterparts in the following ways;
- Reduced moisture buildup
- Reduced soot buildup within the vent
- Reduced creosote buildup
- Less stove “smoking” at startup
The improved performance means you don’t need as much clearance for double-walled stove vents as single-wall vents. While you need at least 18 inches of clearance for single-wall vents, you only need a 6-inch clearance for double-walled vents.
However, single-wall vent pipes also come with several advantages. For one, they’re way more affordable. Additionally, they radiate much more heat into the home and are easier to install.
What Kind of Pipe Do I Need for My Wood Stove?
You need to consider many factors here, including the material, size, length, diameter, and so forth. However, we recommend prioritizing five things;
- Single-wall pipes are the standard: 24-gauge single-walled vent pipes with 18-inch clearance are what most people use.
- Consider double-walled pipes for close clearances: Use Class-A double-walled vent pipes if you don’t have much clearance.
- Match the collar diameter: The stovepipe diameter should match the collar. Most stoves collars are 6-8 inches in diameter.
- Match parts with the same diameter: Woodstove venting systems comprise many other parts, including the collar adapter, thimble, and sleeve. Make sure these parts match the pipe diameter.
Other Considerations Before Installation
Does a Wood Stove Pipe Have to Go Straight Up?
Not necessarily. However, the pipe should be installed as straight as possible, considering that horizontal and diagonal sections slow down the exhaust process. A slowed-down process means the exhaust gases will lose their heat, accelerating wear and tear. Corners also increase the risk of backdraft and the rate of soot deposit.
How Far Does a Wood Burning Stove Need to Be from the Wall?
The National Fire Protection Agency (NFPA) recommends 36 inches. You can place it further from the wall if you wish, though you must also keep the vent piping length in mind. You should always strive to keep the piping length to a minimum.
How Close Can a Wood Stove Be to a Wall with a Heat Shield?
You can place a stove with a heat shield up to one inch or even 7/8 inches from the wall. However, make sure to check what the manufacturer says, as some stoves require at least a 2-inch clearance from the wall with a heat shield.
How to Vent a Wood Burning Stove Through the Wall
Now, we can discuss how to install a wood-burning stove through a wall. Let’s begin with the requirements then discuss how to install the stove and finish by discussing how to run the piping.
Requirements for Running Wood Stove Pipe Through a Concrete Wall
- Angle grinder
- Electric saw
- Screwdriver set
- Spirit level
- A Class A chimney pipe
- Single/double-walled stove pipe
- A through-the-wall furnace vent kit
- Chimney pipe wall straps
*A through-the-wall furnace vent kit typically includes a chimney tee connector with supporting brackets, pipe wall straps, thimble, adapter, and the chimney pipe to run through the wall.
How to Install a Wood Burning Stove Through a Wall – Step-by-Step
The following is a step-by-step process to install a Class A wood stove venting system through the wall. Take note that this doesn’t apply to stove pipes or chimney connectors.
Step 1: Choose a location
The first step is to choose a location on the exterior wall through which the flue pipe will exit. The most important thing here is clearance, which is dictated by the type of pipe chosen.
As we saw earlier, you can either work with single-walled or double-walled flue pipes as triple-walled pipes are no longer fashionable. You need at least 18 inches of clearance for single-walled flue pipes and at least six inches for double-walled pipes. Additionally, you need at least 12 inches of clearance between the pipe and the ceiling or floor.
Step 2: Measure and mark
Next, measure the required clearance and mark the pipe exit location so you can out that part of the wall. We recommend using a pencil to mark the location as you can erase pencil marks more easily if you make a mistake.
We strongly recommend using your wall flashing and thimble as a template. Place the flashing and thimble on the identified location, mark the circle, and place a dot in the center. Then use a tape measure to determine whether you have enough clearance by measuring from the edges of the marking.
Step 3: Cut and remove the wall
If you have enough clearance, the next step is to cut and remove the wall from the selected location. You’ll need three tools for this process – an angle driver, a saw, and your protective gear.
Use the angle grinder to cut through the concrete, the saw to cut through wood pieces, and your PPE to protect yourself throughout the process. Be careful not to cut electrical wires and plumbing pipes.
Removing the wall after cutting is easy. Use a drill to drive a long screw into the cut section of the wall. You can drive it into the dot we mentioned earlier. Then, pull out the cut section using the screw. It will come out without much fuss.
Step 4: Install the flashing and chimney to the exterior wall
This is where real work begins. You’ll need a second pair of hands to help you connect the different pieces and the spirit level to check that the level is right for each component.
Begin by attaching the flashing to the wall. Then install the tee support and the galvanized tee. The tee is the bottom segment of the chimney pipe stack.
Then, add chimney pipe segments one by one until you reach the roof’s eaves. Don’t forget to add wall straps every 4-5 inches to hold the chimney segments firmly to avoid sagging. Also, don’t forget to maintain the mandatory clearance.
Step 5: Connect the tee to the wall thimble
This step involves installing the chimney pipe that runs through the wall then connecting the pipe’s tee to the internal wall thimble that goes into the interior wall. Ensure the thimble is matched to the diameter of the chimney pipe as we mentioned under the “what type of pipe do I need for chimney” section.
Step 6: Finish up and install the stove pipe
Attach the chimney pipe to the internal wall thimble. The thimble is mounted and screwed onto the wall just as we did with the exterior chimney pipe tee bracket. Once done, the final step is to transition from the high-temperature chimney pipe to the single or double-walled stove pipe.
The easiest way to do this is to use an adapter. First, attach the stove pipe to the wall pipe using the adapter, then attach the setup to the top of the stove using a stovetop adapter.
How Do You Install a Double Wall Pipe Through a Wall?
The easiest way to install a double-wall flue pipe through the wall is to place it through the wall of the room in which the stove is located. Run the flue straight up the side of the house, ensuring minimal obstacles along the way. When passing it through the wall, you can only use a 45° slant or less.
The law requires using a metal sleeve around the flue when passing a double-walled flue pipe through the wall to prevent damage from heat expansion. Above all, you’re only allowed four bends throughout the pipe length.
How Do I Install Wood Stove Pipe Through Metal Wall?
It’s strongly prohibited. However, if you must install a wood stove pipe through a metal wall or any other combustible wall, you must work within the following guidelines as per the NFPA;
- Build a 3.5-inch-thick brick masonry wall framed into the wall, maintaining a 12-inch clearance between the clay liner and the wall.
- Use a solid, insulated, L-listed factory-built chimney for venting while maintaining a 9-inch clearance to the wall.
- Make sure to use a 24-gauge sheet-steel chimney connector with a ventilated thimble. You must also apply at least six inches of fiber insulation.
Additionally, your connectors must maintain a ¼ inch pitch pe foot from the wood stove to the chimney. Also, avoid sharp turns and secure the flue pipe system firmly to prevent dangerous sagging.
Can You Install a Wood-Burning Stove in the Basement?
Yes, you can install a heat-efficient wood stove in the basement as long as you work with existing code and safety guidelines. Begin by checking the local authorities to determine if basement wood stove installations are allowed in your area. If so, peruse the codes to find out restrictions on the same. Typically, the flue pipe must vent into a chimney that vents three feet or more above the roofline.
From there, you can begin the installation. Ensure the stove is positioned at least three feet from the closet wall to create a safe zone.
Installing a wood-burning stove through the wall isn’t too difficult. However, the existing codes and legislations make it a daunting task. Make sure to purchase the correct materials (stovepipes, chimney pipe, and everything else) per your local codes and install the unit according to the same codes. Alternatively, let an HVAC professional handle the entire process for your peace of mind.