Installing a Tiny House Wall Exit Flue System

Before you begin

  • Your flue design should be complete, and you should have all the required components on hand.  The install kit is the "base kit" that includes the parts that most everyone needs.  Since every structure is different, people need varying amounts of pipe in addition to the kit.  Consult our flue design resources or contact us for help designing your flue system.
  • Your stove should be assembled and your hearth built.  Consult the Dwarf Manual for instructions on your hearth, proper clearances, and heat shields.  Watch the unboxing video for help with stove assembly.  If you're building in a mobile structure like a Tiny House on Wheels, the structure should be level before you start work.

You Will Need:

  • Screwdriver
  • Ladder
  • Level and/or plumb bob
  • Wax pencil or sharpie
  • Tools to cut a hole in your exterior wall.
  • Fasteners to attach your flange to your wall inside and out, and to attach the tee support and wall support to the exterior of your structure
  • Latex or silicone caulk to seal behind the thimble flange on the exterior of your structure

You May Need:

  • Chop saw or angle grinder with a metal cutoff blade to cut single-wall pipe.
  • Sheet metal crimpers to adjust crimps.
  • Stovepipe screws if you're not using clamps to secure your joints.
  • Drill
  • Stud sensor

Step 1: Attach stovepipe to flue flange

The first section of stovepipe must be sealed to the stove's flue flange with stove cement.  Since the stove needs a flue system to function, and both the stove cement and the stove's paint are heat cured (which can generate some chemical fumes), we recommend curing the stove paint and the cement outside, at the same time.

If you are using a rear exit configuration with the pipe passing through the wall behind the stove before turning to vertical, it may not be practical to perform an outside burn before installing.  If this is the case, seal the first section of stovepipe into the flue flange as described in this step, and then ensure your structure is well ventilated when performing your first burn inside.

If you're connecting insulated pipe directly to the stove's flue flange for an all-insulated chimney, the inner wall of the pipe will need to be crimped to fit inside the flue flange.  We can do that for you prior to shipping your order, or you can do it yourself with a sheet metal crimper.  Crimp the pipe only as many times as needed for the pipe to bottom out on the flue flange.  Over-crimping will make the pipe loose inside of the flange.

Apply Stove Cement

Cover the inside of your flue flange and the outside of the male end of your pipe with stove cement, and connect them together.  Use a bubble level to ensure that both your stove and your stovepipe are perfectly plumb.

Thoroughly clean off any excess stove cement before firing your stove.  It is very difficult to remove stove cement once it's cured.

If the pipe is very loose inside of the flue flange, a thicker stove cement might be helpful.  High heat furnace cement sold in a tub works well.  Try to find it in black for best results.

Install Screws (Optional)

Stovepipe screws are not required to secure stovepipe into the flue flange, but can be optionally added for additional security, or to hold the stovepipe in place until the cement cures.  If you choose to add screws, use three heat-proof screws evenly spaced around the flue flange, and drill pilot holes through the the flue flange and stovepipe before installing them.

Complete Outside Burn

Add additional sections of stovepipe to get at least 40" of vertical pipe, and build a fire in your stove outdoors to complete your initial cure according to the instructions in the Dwarf Manual.

Once your stove has cooled, move it back inside and secure it in place on the hearth.

Step 2: Cut the hole through your wall

The hole in your wall needs to be aligned with the pipe attached to your stove, and should be large enough to allow the center of the thimble to fit through the hole.

Mark the Cutout

Determine the center point where your flue will penetrate the wall.  If you're exiting at a point above your stove, make sure the wall penetration is centered vertically above the stove's flue flange.  If you're exiting directly behind the stove before turning to vertical, make sure the center of the hole in the wall is precisely lined up with the center of the rear flue flange.

Mark the area around the center point where you'll need to cut material away to allow the thimble to pass through the wall.  You can separate the two halves of the thimble and use the thimble itself as a template for your cut.  The 4" thimble needs a 10" diameter hole, and the 5" thimble needs an 11" diameter hole.

Cut Through the Wall

Make sure the area your chimney will pass through the wall doesn't intersect with any studs, pipes, or wires.  A stud sensor can help to detect studs, but may not indicate the presence of wires or pipes.  If you're not sure, make a small exploratory hole in the interior wall first to get a look.

Cut through the interior wall with an appropriate tool for your wall material.  A scroll saw or reciprocating saw tend to work best for wood, while a sheet metal nibbler typically works best for sheet metal, and a keyhole saw works well for drywall.

Inside of your wall, cut away any remaining insulation or other material in the way of the thimble.  Then, mark the center of your cutout on the inside of the exterior wall and drill a hole through to the outside.

Using the hole you just drilled as a reference point, mark the perimeter of your cutout on the outside of the exterior wall.  Then cut around the perimeter through your exterior wall.

Install the Thimble

Install both thimble halves from opposite sides of the wall and secure in place with fasteners appropriate for your wall material.  Insulation can touch the outside of the thimble, but there should be no insulation or other material inside of the thimble.

Use exterior grade silicone or latex caulk behind the top and sides of the exterior thimble flange on the exterior wall of the house to prevent driving rain from entering the wall behind the thimble.  Leave a gap in the caulk at the bottom of the flange to allow moisture to drain away freely.

The thimble is designed for 2x4 or 2x6 walls.  If the wall is too thin for the thimble, you can remove material from both sides of the thimble with an angle grinder to make it thinner.  If the wall is too thick, you may need to add additional 24 gauge sheet metal around the thimble to ensure clearances to combustibles are properly enforced.   The two sides of the thimble must overlap so that it's not be possible for anything (insulation, rodents, etc) to reach the inside of the thimble from the inside of the wall.

Step 3: Install your stovepipe

With your wall thimble installed, you'll now build your flue system and attach your exterior chimney to your structure.  Assemble your stovepipe using a clamp at each joint to secure the pipes together.  Alternatively, three stovepipe screws can be used to secure each joint.  No cement or caulk is required or recommended at pipe-to-pipe joints.

Assemble the Tee, Tee Support, and Horizontal Pipe

Assemble the tee support bracket by attaching the two triangular supports to the underside of the rectangular tee support bracket plate with the provided bolts.  Attach the cleanout cap (part of the insulated tee) to the bottom of the tee support bracket.  Attach the tee support bracket to the bottom of the tee.

Align the tee support bracket so that the wall side of the supports are facing the same direction as the opening on the side of the tee (i.e. the "tee leg").  Attach the insulated pipe used for the horizontal run (typically a 10" section) to the side of the tee, and attach the single-to-double adapter to the other end of the horizontal insulated pipe.

If you're having trouble getting the single-to-double adapter or another piece of insulated pipe to fully bottom out on the next piece, check the metal trim ring in the bottom of the insulated pipe.  The trim ring should be pushed fully into the groove that mates with the clamp around the joint.  If the trim ring is not fully seated, it may prevent the piece below from bottoming out.  Push the trim ring in until it is fully seated, and try assembling the pipes again.

Install Tee Support and Horizontal Pipe

Place the insulated pipe through the wall thimble from the outside of the structure, with the tee support bracket touching the exterior wall.  Verify that the inside of your pipe lands where you need it, and adjust the tee support bracket accordingly, ensuring that the vertical portion of the insulated tee stays at least 2" away from the exterior wall.

Center the pipe in the thimble.  There should be a small amount of space around the outside of the pipe, inside of the thimble.  You will seal this gap with high temp RTV silicone in a later step.

Use a bubble level to ensure the tee is oriented perfectly vertically, and fasten the tee support bracket to the exterior of your structure.

The insulated pipe must extend far enough into the room to avoid a clearance violation from the single-wall pipe and the rear of the stove.  A heat shield is usually required for the standard wall exit configuration.  Ensure there is at least 18" clearance to combustibles from the single-wall stovepipe and the rear of the stove, or use heat shields to reduce the required clearance to no less than 6".

Install Connector Pipe

Connect the remaining single-wall pipe from your stove to the 90 degree elbow connecting to the single-to-double adapter, using a single-wall clamp or three stovepipe screws at each joint to fasten the sections together.

The center joint of the telescoping pipe is meant to be free-floating and does not need to be clamped or screwed.

Single-wall pipe can be cut to achieve the length you need.  Cut the pipe with a chop saw or angle grinder with a metal cutoff blade.  You can use a single-wall clamp as a guide and a sharpie or a wax pencil to mark your cuts.  Cut the female end off and preserve the factory male end on the piece you're going to use.

You can cut the female end off a longer single-wall pipe and insert the top of the telescoping pipe inside of it to make a longer telescoping section.

Each piece of Tiny Wood Stove pipe has a top and a bottom.  Since the pieces will only fit together in one direction, maintaining the proper orientation is usually straightforward.  If you find a piece won't fit because you have a male-to-male or female-to-female end, something is probably upside-down.

Single-wall male ends (and male inner walls of insulated pipe) should point down toward the stove to contain any condensing liquids or creosote inside your flue system.  Outer wall male ends of insulated pipe should point up to help shed rain water outside of the pipe.  Note that the orientation of the insulated pipe inner wall is opposite the orientation of the outer wall.

Step 4: Assemble the chimney

Assemble your vertical chimney on the outside of your structure by connecting the insulated pipes together and securing with clamps.

Install Chimney Supports

Install the wall support bracket as high as possible on your structure, up to 6 feet above the tee support bracket.  If there is more than 6 feet of pipe above the tee support bracket and below the roof line, use additional wall support brackets (sold separately) evenly spaced, at least one every 6 feet.

If you are using an extended chimney support bracket, install the clamp on the pipe at least 3 feet above the roof line and no more than 5 feet from the top.  Adjust the arms of the bracket to reach points on the high side of the roof on either side of the chimney.  A 60 degree arm angle relative to the vertical chimney is ideal.  Secure the feet of the arms to the roof using appropriate roofing fasteners and roofing sealant.  We recommend applying sealant to the threads of each fastener prior to installing it, then burying the entire foot in roofing sealant.

Cap Your Chimney

Secure the roof vent to the top of your chimney with a clamp.

Seal the Thimble

Use the included high-temp RTV silicone to seal the gap between the insulated pipe and the inside of the thimble on the exterior of your structure.  It is not necessary to seal the corresponding gap on the interior side.

Step 5: Inspect your installation

Verify Chimney is Supported

The tee support and wall support(s) should fully support the weight of the chimney, and prevent lateral movement.  If the chimney stands 5' or taller above the highest wall support, it should be reinforced with an extended support bracket.

The interior connector pipe should be stable, fully supported by the stove at the bottom and the horizontal chimney pipe at the top.

Verify Joints are Secure

Ensure every pipe-to-pipe joint has either a clamp or three stovepipe screws (except for the center joint of the telescoping pipe which is free-floating).

Check Clearances

Check for clearance violations around your stove and your flue system.

The Dwarf stove requires 18" clearance from the back and 16" to the sides.  Third party stoves may require different clearances, so check your user manual or contact the manufacturer if needed.

Single-wall pipe requires 18" clearance to combustibles. These clearances can be reduced by up to 2/3 with a proper air cooled heat shield between the heat source and any combustible materials.  Insulated pipe requires 2" clearance to combustibles in all directions.

Larger clearances are always acceptable.

Questions?

If you aren't sure about any part of your flue installation, please get in touch!  We are here to help however we can.  You can contact us by email at support@tinywoodstove.com, call us at 208-352-3417, or use the contact form below.

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