Woodstove Chimney – Best Route Out
I’m in western New York State – snow country. I recently built a two-story, three-sided addition on the back of my c.1835 farmhouse. We insulated it with high-density closed cell spray foam, and plan to complete the job with unfaced batt insulation on the interior. We are installing a nice soapstone woodstove on the west wall, and have to chose between two routes for the stove pipe, each with its own pros and cons:
1) Run the pipe up through the second floor into a chase just inside the exterior wall, and up and out the roof (the foam insulation was sprayed to the underside of the roof decking, between the rafters). We would need a couple of 45 angles to direct the pipe where we want it to minimize disruption to the bathroom layout above – otherwise it’s basically a straight run up and out.
2) Run the pipe up about six feet or so up out of the stove, and then take a 90 angle out the wall. Another 90 angle outside to get vertical, then straight up through the overhang to the required clearance height for the roof. The exterior pipe is well sheiled from view – we’re not too worried about how it looks.
There are differences in the cost for the various lengths of the different types of pipe required for each setup. The critical questions on this job are: 1) overall cost; 2) day-to-day performance and draft for the stove; 3) aesthetics inside and outside the house, and 4) air infiltration. It seems like cutting a hole in the west wall for the pipe is inviting cold air into the house as it infiltrates the gap around the through-pipe and collar, and as cold air fills the chimney pipe and sinks down its path into the house. On the the other hand, the pipe going up through the house should draft better, although it too can funnel cold air inside. But there, the way in for cold air is way up in the attic, not in the living room.
Any thoughts on the subject are greatly appreciated.
Replies
#1 would be preferable to me, because it will result in less formation of creosote due to cooling of the flue gases, and this means less chance of a chimney fire.
Air infiltration by either method is about the same.
Around here you'd need to use insulated triple-wall pipe on the exterior to keep the gases hot to cut down on creosote buildup. But that stuff is seriously expensive. I hardly ever see it done this way.
#1 would be my preference too, but obviously you'll need to thoroughly study manufacturer's instructions for details on materials and clearances. Keep bends to a minimum both for draft purposes and for ease of cleaning.
#1
More pipe inside, hotter flue gas, no 90 elbows, etc.
Nobody wants to cut a hole in their roof
I recently installed a wood burning stove in my workshop. The installation process was a bit different than traditional wood frame construction since it is a metal building.
In looking at several installation diagrams, I originally wanted to do some crazy first up, then over, then out the back wall then up again. I was convinced to go with a straight-up through the roof configuration by a local stove expert.
The guy who helped me said most everyone tries to avoid going through the roof. In fact nobody has ever said I want to cut a big hole in my roof. Crazy configurations are what people start with and this is normal.
I posted a bunch of photos and entries about my stove installation. Check it out: http://www.diybackyardworkshop.com/tag/wood-stove/
This is for an older stove from the 1970's. The model is called a Fisher stove and was used by my wife's family to heat their home when she was growing up. Now it heats our workshop. Kinda cool... or hot.
that stove looks familiar.........
I bought a Fisher like that in the 70's, seems like it was about $300 which was a fair bit of my carpentry wages at the time. It had a 30 year warranty but I believe the company long ago folded.
It has served as my primary source of residential heat every winter since, looks to be good for more years to come.I'm inclined to think it was a sound investment...............