A Wood Stove in the Basement Needs a Code-approved Vent
I would like to put a wood stove in my basement, which is made from concrete block. What type of stove pipe should I use and how do I get it through the wall?
Chilly fall evenings can make a wood stove seem like a great idea. Even at today's higher prices, wood is usually a cheaper heat alternative than fuel oil or gas. A cord of dry hardwood has roughly the same heat potential as 140 gallons of fuel oil and costs a lot less.
But before we get to the stove pipe, let's start with the basement installation itself.
Unless you have an insulated basement, you're going to lose a lot of heat through the foundation walls before you ever get a chance to enjoy it upstairs. Concrete has essentially no insulating value. Block exposed to outdoor air is a perpetual heat sink. And don't forget about the frozen earth banked up against the foundation. In midwinter, that could easily be two or three feet deep.
Circulating hot air from the basement into the rest of the house is another issue. Heat registers cut through the floor help move some warm air via convection, but it won't be as effective as a fan and dedicated ducts. This helps explain why your house feels chilly even though you're filling the woodstove with the best split oak money can buy.
If you are set on a basement installation, you need either a masonry chimney or a prefabricated metal chimney to vent combustion gases safely. Masonry chimneys are relatively expensive, and unless you know what you're doing it's a job best left to a pro. Installing a prefabricated metal is something you may be able to do yourself. Although the materials are not cheap, it's probably a more affordable option.
Double-walled metal chimney sections are insulated with mineral wood and can be placed a few inches away from combustible materials. Sections lock together without fasteners, and a variety of fittings and adapters are readily available.
What you want is Class A stove pipe, rated for temperatures of up to 2,100 degrees--not because your woodstove can produce that much heat but because a chimney fire might.
It might be possible to punch a hole through the top of your block foundation and run the pipe out there. In that case, the chimney would have to run up the outside of your house and extend above the roofline. And you'd have to find a way to attach a support on the outside wall to bear the weight of the chimney.
You would be better off routing the chimney through the house and venting it at the roof. That keeps the chimney warmer, improves the draw of the woodstove, and lessens the buildup of creosote.
Start by visiting a well-established stove shop that can help you design a safe and efficient system and order the parts you're going to need. If you want to do a little background reading in advance, the Woodstock Soapstone Company offers an excellent technical library at its web site (www.woodstocksoapstone.net).
Woodstoves can be great, but they also can burn your house down. Make sure you do this right.