Chimney Pipe / Venting Pipe

How to Determine the Right Elbow Angle for Your Woodstove Pipe

Selecting the correct elbow angle for your 6-inch double wall stove pipe is all about matching the elbow to the offset you need in your installation. The degree of the elbow - whether 45°, 90°, or something in between - should be chosen based on the change in direction required to navigate around obstructions or align with venting points.

Here's a quick way to approach it:

• Measure the Offset: Determine how far you need the pipe to shift horizontally from its original path.
• Consider Your Space Constraints: Tight spaces might require sharper angles, while gradual direction changes can use lower-degree elbows.
• Use Manufacturer Specifications: Most brands, like Vortex or DuraVent, provide charts to help you match your offset distance to the correct elbow angle.

By mapping out your layout and measuring carefully, you can select the elbow that ensures a safe, efficient, and tidy installation.

Offsetting Chimney Pipes Around Obstacles

When you need to route a chimney pipe around an obstruction - say, a roof beam that refuses to budge or an oddly placed rafter - elbows come to the rescue. These handy pipe fittings allow your chimney system to change direction smoothly, helping you get from point A to point B without launching into a home remodel.

Choosing the Right Elbow

• Many systems offer elbows at either 45° or 90°. However, with Class A chimney pipe, you'll typically work with 30° elbows. (Sorry, daredevils, that's the max angle allowed for safety and airflow.)
• For Class A, you'll need two elbows: one to start the offset, another to get you back on track vertically. Manufacturers like DuraVent and Selkirk usually package them as a kit - complete with an elbow strap for support.
• Offsetting rules are strict: most setups allow a maximum offset of just over 3 feet between elbows for Class A pipe.

Offset Distances by Pipe Type

• Stove Pipe: Can offset nearly 60 inches to skirt tricky beams or other obstructions.
• Direct Vent Pipe: Offers flexibility with offsets up to around 40 inches.
• Pellet Vent Pipe: The workhorse here, tackling almost 80 inches if needed.

These measurements are general guidelines - always double-check your stove's manual and specific pipe manufacturer's instructions. Safe installation is all about following those specs to maintain proper draft and efficient flow.

Support Straps and Their Role

• Elbow Straps & Wall Straps: When installing a chimney system with any directional changes - like using a 45° elbow - a sturdy support is key. Elbow straps are designed to bear the weight of offset sections, securing everything neatly in place. Meanwhile, wall straps come into play for vertical runs, especially when your pipe hugs a wall or climbs inside a chase. Spacing these about every 4 to 5 feet helps maintain proper alignment and keeps your setup safe and steady, no matter how long the vertical rise.

How to Transition from Stove Pipe to Chimney Pipe

When it's time to connect your stove pipe to your insulated chimney pipe, the right parts - and a bit of planning - will save you a world of hassle (and head scratching).

There are two main ways this transition typically happens, each with its own special hardware:

• Through-the-Ceiling:
  If your venting runs straight up through the ceiling, a ceiling support box or a round ceiling support is your go-to. Simply attach the stove pipe to the bottom opening, then connect the insulated Class A chimney pipe above. The support box holds everything in place, while an attic insulation shield or roof flashing ensures a safe path through any attic or roof. For chimneys built inside a wooden chase, you'll want to cap things off with chase top flashing for extra weather protection.

• Through-the-Wall:
  Running the pipe horizontally through a wall? You'll need a wall thimble. This piece acts as a safe conduit for the chimney pipe, allowing it to pass through the wall and connect on the inside to your stove pipe. Keep in mind, double-wall stove pipe needs the chimney pipe to extend at least six inches into the room for a proper connection (single-wall pipes need 18 inches).

A few pro tips:

• Most modern wood stoves have the flue collar on top. Always include at least 12 inches of vertical rise - using straight stovepipe - before installing any elbows or horizontal runs. This helps with both draw and safety.
• Rear-vented stoves work best with a tee at the collar for future cleanout. They also need a short vertical section before making the turn toward the wall.
• Always refer to your stove's manual and stick to UL listed pipes - Selkirk, Simpson Duravent, and similar brands are your friends here.

Making these connections with the right adapters and supports means you'll have a safer, smoother-running installation.

Anchor Plates & Flue Adaptors: Essential Connection Hardware

To safely and securely connect your fireplace or stove to the chimney system, you'll typically need either an anchor plate or a flue adaptor.

• Anchor plates are most often used with zero-clearance and masonry fireplaces. They serve as the crucial base, fastening directly to the appliance and providing a stable connection point for the chimney pipe above.
• Flue adaptors are commonly used with wood stoves and some direct vent fireplaces. These adaptors ensure that the flue outlet of your appliance mates perfectly with your chosen stovepipe or chimney type, especially if the sizing or connection style differs.

Whether you're installing a zero-clearance wood-burning fireplace with an 8" flue and connecting to DuraVent's DuraTech system, or a wood stove with a 6" vent using DuraVent DVL double-wall pipe, matching the correct anchor plate or adaptor is key. This not only streamlines your installation, but also ensures a safe, gas-tight transition from appliance to venting system.

Can You Use a 6" to 5" Adapter with a Stainless Steel Liner?

If you're considering reducing your 6-inch stainless steel liner to 5 inches somewhere along your masonry chimney, here's what you need to keep in mind:

• Most wood-burning appliances, especially inserts, are specifically designed and tested to vent with a 6-inch diameter liner from top to bottom.
• Dropping down to a 5-inch liner, even with an adapter, generally isn't allowed - and can lead to draft issues, decreased performance, or even violate local codes and manufacturer warranties.
• Always check the installation manual for your specific stove or insert. The recommended flue size is there for a reason, and reducing the diameter can cause safety or operational problems.

In short, for nearly all wood inserts, you'll need to stick with a consistent 6-inch liner throughout the chimney - no reductions along the way. If you're in doubt or have a non-standard setup, consult a certified chimney professional to review your installation before proceeding.

Which Pipe Do You Need for Your Fireplace Insert?

If you're planning to install a fireplace insert into a brick fireplace with a 16" square chimney and a 6" outlet on the insert, you'll want to use a 6-inch diameter stainless steel chimney liner. This type of liner is designed to connect directly to your insert's 6" flue collar and then run all the way up through the existing masonry chimney to the top.

Why stainless steel? It's highly durable, resists corrosion from exhaust gases, and ensures your fireplace insert vents safely and efficiently. Flexible stainless steel liners are the most popular choice, as they can navigate angles or offsets within older brick chimneys, but rigid liners can also work if the chimney is straight.

When installing, you'll typically need the following components:

• 6" Stainless steel chimney liner (flex or rigid)
• Connector/adaptor for the stove's flue collar
• Chimney cap and top plate to secure and weatherproof the liner
• Insulation wrap (if local code or manufacturer specs require it)

Properly sizing and installing your liner not only improves draft and performance, but also reduces creosote buildup and enhances safety. If you're tackling the install yourself, be sure to check local code and your stove manufacturer's requirements. When in doubt, consult with a qualified chimney professional.

Can You Use an Adapter from 6" to 8" Stove Pipe?

Absolutely - a 6" to 8" stove pipe adapter is available and commonly used for exactly this situation. If you're upgrading to a new stove with a 6" outlet but your existing venting is 8" all the way out, you don't have to gut your roof setup just yet.

Here's how it works:

• Simply install a 6" to 8" adapter right at the stove's collar.
• Attach 6" pipe directly to your stove, then use the adapter to connect to the existing 8" chimney connector or Class A chimney transition.
• This lets you make the transition neatly, without replacing your upper chimney or poking new holes in the roof.

Just be sure to:

• Double-check your stove manufacturer's guidelines - most stoves want a direct 6" run for proper draft, and some get picky if you upsell the size too quickly.
• A properly made adapter ensures a snug fit and a smooth transition, especially if you stick with trusted brands like Vortex, DuraVent, or Selkirk.

If you're unsure, check local code or chat with a professional installer - safe venting is key for efficient burning and peace of mind.

Flashing & Storm Collar
A flashing and storm collar combo is a must-have for weatherproofing your chimney system. The flashing covers the roof penetration, ensuring a snug fit where your pipe passes through, while the storm collar wraps around the pipe just above the flashing. This dynamic duo keeps out rain and snow, sealing any tiny gaps between the pipe and flashing for solid protection against the elements.

When selecting your flashing, make sure it matches your roof pitch. Roof pitch is the amount your roof rises vertically for every 12 inches it runs horizontally. For example, a 3-inch rise over a 12-inch run means you have a 3/12 pitch. Choosing the right flashing for your specific pitch ensures a secure, weather-tight installation.

What Are Flashing and Storm Collars?

When it comes to keeping your chimney system protected from the wrath of Mother Nature, flashing and storm collars are the unsung heroes.

Flashing is a metal component that creates a weatherproof seal where your vent or pipe pops through the roof. Essentially, it covers and shields that vulnerable opening, helping to prevent rain, snow, and debris from sneaking inside your home. The type of flashing you need is determined by your roof's pitch - so be sure to check whether you have, say, a 3/12 or a 5/12 pitch before picking one up. (For the uninitiated, roof pitch refers to how many inches your roof rises vertically for every 12 inches of horizontal run.)

The storm collar works in tandem with flashing. It wraps snugly around the pipe, sitting just above the flashing, and acts as an extra barrier to direct water away from the penetration point. Think of the storm collar as the trusty sidekick - helping ensure even wind-driven rain won't find its way into the seams.

Together, these two pieces help keep your chimney installation dry and robust, no matter what the weather forecast may conjure up.

Important Considerations

If you're repairing or updating an existing system, it's crucial to match your new pipe to your current make and model. Codes and manufacturers usually don't allow adapters to connect different brands (unless a manufacturer provides one for a discontinued model). If your existing pipe is obsolete, you may have to rebuild your chimney system - there's no shortcut around the rules here.

In summary:
Any wood-burning stove or fireplace will require Class A chimney pipe for safe operation. For gas appliances and certain other systems, other venting options might suffice, but when in doubt, consult your local codes or a pro - and always put safety first.

Double-Wall Pipe Installation Tip

One common question: when connecting your double-wall pipe from the top of your woodstove to the flue extension under a square support box, should the stovepipe fit inside or outside the collar at the bottom?

For proper installation, the double-wall pipe should fit on the outside of the flue collar at the base of the support box. This ensures a safe and secure connection, while allowing any condensation or creosote to flow down inside the pipe where it belongs. This approach is standard for DuraVent, Selkirk, and similar venting systems.

Clearance Requirements for Stove Pipe

When installing stove pipe, it's important to observe the minimum clearance distances to keep things safe and up to code. The required distance depends on which type of pipe you're working with:

• Single-wall stove pipe: This variety demands more breathing room, so you'll need to leave at least 18 inches of space between the pipe and any combustible wall or ceiling.
• Double-wall stove pipe: These are a bit more forgiving. For double-wall, you'd only need to maintain 6 inches from the wall and 8 inches from the ceiling.

Always double-check the manufacturer's instructions for your specific product, but these guidelines from leading brands like Selkirk and DuraVent will keep you well on your way to a safe installation.

What Is Stove Pipe and How Does It Compare to Class A Chimney Pipe?

If you're putting together a wood stove setup, you'll want a handle on the essential difference between stove pipe and Class A chimney pipe - two terms that tend to cause more confusion than a squirrel in a bird feeder.

Stove pipe (often called a chimney connector) is the section of venting you see running from your wood stove to the point where the venting leaves the room - either up to the ceiling or out the wall. It's designed for use only within the same room as your stove. Once your run hits the ceiling or wall, it's time to switch over to Class A chimney pipe, which is built to manage higher temperatures and safely pass through walls, ceilings, or attics.

Stove Pipe at a Glance

• Location: For interior use only; think of it as the first leg of your stove's journey to the great outdoors.
• Types: Comes as single-wall or double-wall. Single-wall requires more space from combustibles (usually 18"), while double-wall allows for snugger clearances (as little as 6-8", depending on the direction).
• Duty: Its job is to carry smoke and hot gases safely across the room - but not through any barriers.

Why Not Use Stove Pipe Everywhere?

It's tempting to let your stove pipe do all the work, but here's the catch: it's not engineered for passage through walls or ceilings, no matter how many inches of clearance you manage to rustle up. Even with double-wall versions, stove pipe simply doesn't provide the safety features needed for installation through structures. It can't maintain the necessary flue temperatures outdoors, either, which risks creosote buildup and a potential fire hazard.

Enter Class A Chimney Pipe

• Role: This heavy-duty pipe is designed for venting smoke through any part of your house's structure - attics, walls, and roofs all included.
• Construction: Built with insulation and multiple walls (hence "Class A"), it eats high temperatures for breakfast and only needs about 2" of clearance from combustibles.
• When to Use: The moment your venting leaves the room the stove lives in, it's time to upgrade to Class A chimney pipe to comply with codes and keep everyone safe.

Bottom line: Stove pipe gets the smoke out of the room. Class A chimney pipe takes it the rest of the way - through your house to fresh air, all while managing the heat and hazards along the way. Both are must-haves, and knowing when to use which saves you from headaches (and potential house fires) down the line.

Mixing Double Wall and Triple Wall Chimney Pipe

If you're hoping to switch between double wall (double insulated) and triple wall (triple insulated) chimney piping in the middle of your venting run, unfortunately, it's a no-go. These systems are engineered to work as one continuous type - from start to finish. This means that once you pick a style and manufacturer (think brands like Selkirk, DuraVent, or Metal-Fab), you're locked in for both type and size all the way up. There are no adapters available for transitioning between double wall and triple wall chimney pipes from any major manufacturer, and mixing systems can lead to significant safety risks - not to mention voided warranties and code violations.

Adapters do exist for connecting black stove pipe (the part visible in your living space) to your chimney system, but once you get to your chimney pipe, you must stick with your chosen configuration throughout the entire install. So, choose carefully at the start and double-check compatibility for a hassle-free, safe installation.

Can I Use Double-Wall Stainless Pipe All the Way Through My Shop Roof?

If you're planning to vent your stove through your shop roof using double-wall stainless pipe, you're on the right track for good performance and durability - but there's an important detail to consider. Inside your shop, double-wall stainless pipe is fine for connecting the stove to the ceiling or wall where the chimney system begins. However, once the venting passes through any part of the building structure (like the roof or wall), building codes require that you transition to a Class A chimney system (sometimes called "all-fuel" chimney). This kind of pipe is designed and rated specifically to safely vent high temperatures through combustibles.

In short:

• Inside: Double-wall stainless pipe is great from stove to ceiling/wall support.
• Through Roof/Wall & Outside: Switch to a UL103 HT-listed Class A chimney system.
• Finish: Top it with a compatible rain cap to protect your system and keep critters at bay.

Following this approach ensures your installation is both safe and up to code, keeping you worry-free and warm.