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OT - Woodburner Installation

John in OH

Aluminum
Joined
Feb 7, 2002
Location
SE Ohio, USA
I hope to get a woodburner installed in my secondary tractor shed / workshop before the snow flies this year! The shed is a pole barn with a typical truss roof support system and asphalt shingles. Ceiling is a random mixture of drywall and plywood. Does anyone know how the smokepipe should be installed where it penetrates the ceiling at the bottom of the trusses? What is used to protect the ceiling from the heat of the pipe? Thanks - and next time I'll try to keep more to the machinist topics!
 
John,

My father has done this in his cabin. All I know is that he used triple insulated pipe and some sheet metal. If you want to talk to him directly, email me and I'll give you his phone number.

Eric
 
You can use what's called all-fuel chimney. Its a triple wall pipe and can be used with near zero clearance to combustibles. Its also seriously expensive. Just don't let anyone tell you that its okay to use a double wall type B gas vent on a woodburner. Very good way to burn the building down. There are ways to use single wall flue pipe in applications like yours, but they generally involve having to cut away anything combustible for a substantial distance or otherwise wrap the pipe in the vicinity of combustibles with a couple inches of mineral wool.....not a fun thing to do. You can use all fuel sections as thimbles where you have penetration of combustibles and use single wall pipe for the remainder. The nominal diameter of the all fuel is based on its ID and thats where the single wall material would connect to it. If it were me, unless there's a large distance between the ceiling and the roof, I'd run all fuel from below the ceiling continuously thru the attic space and out the roof. You can purchase a vent cap, adjustable flashing, and storm collar that is made to work with the all fuel to make the termination at the top and have a weatherproof installation. These parts arent very costly. If you check with a local heating supply house, they should be able to tell you what the local code requires for clearance, as this also determines the minimum distance from the wall to your woodstove or its single wall flue. Ideally, to make for the most cost effective installation, you want to have the stove located such that the flue will hit the center of a truss space and not require any ells to offset it in getting there. If you get into a situation that requires purchasing all fuel ells or tees you can quickly spend more than the cost of the stove on the smokepipe.
 
That triple walled stuff is the stuff to use. However, the previous posters were not kidding when they mentioned the cost. A two foot piece of 6" Galvanized class-A triple wall will set you back around $60, in stainless the same thing is $75 or so. It is really easy to spend more on the vent pipe than you do on the stove.
 
Yah but, you only need to have the triple wall from the ceiling through the roof. Below the ceiling can be standard single wall stove pipe. If you've got a 14' high sidewall like mine, that could get expensive.

Do forget that most codes require a "fire proof" area within 3 to 4 feet of the stove. Most of the time, double 5/8" sheet rock will do.
 
I'm partial to the "Metalbestos" insulated stainless chimney pipe because my local lumberyard stocks it and the instructions are good. Similar installation for any brand.

At the lowest penetration, sounds like your drywall ceiling, you typically box out a 24" square opening that houses a support collar that transitions from single-wall smoke pipe to insulated chimney pipe. This is a metal box that attaches to your framing, connects to smoke pipe below, and to chimney pipe above. It supports the entire weight of the chimney above. The stove supports the single-wall smoke pipe below. The box is wide enough to protect the drywall or other ceiling from the heat of the smoke pipe.

If the drywall ceiling is pitched, you can either frame out a level box below it or get a piched ceiling support kit.

Depending on what insulation is above that, the area between finished ceiling and roof can be left open, or may be boxed in with sheet metal. Any insulation needs to be held away from the pipe by sheet metal. The chimney pipe goes straight through the roof with a cutout in the plywood or skip per the flashing kit instructions.

Typical clearance is 2" to insulation or combustibles for the insulated pipe, vs. 12" or more for single wall so you basically have no choice but to transition to insulated at the first penetration.

Because my shop has an overhead door the inspector said the stove had to be on an 18" tall base. No such thing exists as an off-the-shelf item so it sits on a base I welded from steel angle.
 
I'm using triplewall with my shop stove. When the stove it as hot as I can stand it, the outside of the triplewall is warm to the touch. It works very very well.

Nick :cool:
 
Be sure you use the correct fittings at the top and bottom of the triple wall section if you go that route. You need to admit air (from outdoors) near the top to the outside layer, which flows down to the bottom, then into the inner layer, where it flows up (by convection) and out above the inlet.
You definitely want the inner pipe to be stainless with either type, it's hidden where you can't inspect it and wood smoke condensate is very corrosive. If it rusts through and you don't know it, you get to buy a new roof and maybe whole building.
Also get a chimney brush the right size and wands long enough to clean the whole length, and use it, several times a season if you're burning softwood, a couple if hardwood or you have a catalyst stove. Keep elbows to 30 degrees max each and none if possible.
 
John in OH, Toolbert has the right idea with the ceiling support to make the transition from single wall to insulated pipe. Check your building codes, around here only triple wall is allowed now from the ceiling up. Usually, the stove supply places have install instructions and can help with info/selection. Insurance companies here won't pay off if the install didn't follow code.
 
Having used both I would recommend the "Metalbestos" type, not nessasarily that brand, of insulated pipe rather than the triple wall. The triple wall I used corroded to useless in two years, and it was stainless inner pipe. I now have two chimneys using the "Metalbestos" type of insulated pipe which is stainless inside and out. Zero trouble with it after almost ten years. It is expensive, about $1.50 to $2.00 per inch, perhaps more now, but well worth it. It is easily installed as is vertualy maintenance free except for regular cleanings like any chimney.
 
Good ideas but check with your insurance company if you want to insure the building.My company will not insure any shop or other building if not a primary residence if heated with wood.Surprisingly they will insure if heated with anything else,even a corn stove,waste oil heater,gas furnace etc.
 








 
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