The Forestry Forum

General Forestry => Firewood and Wood Heating => Topic started by: shinnlinger on December 09, 2014, 07:31:22 AM

Title: Wood stove make up air?
Post by: shinnlinger on December 09, 2014, 07:31:22 AM
Hello,

I could run a pipe to my woodstove area from outside without a lot of fuss.    Is it worth it?   How big a pipe for a 16ft run with an elbow or two?  Would a sewer vent one way valve outside be good?   Ideas?   Pointers?

Thanks

Dave
Title: Re: Wood stove make up air?
Post by: sprucebunny on December 09, 2014, 08:52:38 AM
They make a barometric damper that fits in 6" duct. I have one on my furnace PowerVent. They might make a smaller one ...
It would still leak a little air but it's operation is adjustable.

If your house is extremely air tight and you have trouble keeping draft going the right direction in your woodstove, you may benefit. If you are not having trouble with the house filling with smoke mid-burn or the fire going out, then I wouldn't bother. Maybe you could do a test by making a piece of wood to fit in a nearby window that you can adjust a small opening ???
Title: Re: Wood stove make up air?
Post by: Tom L on December 09, 2014, 11:09:05 AM
I have a 4" flex pipe going from my stove to the outside, for intake air, it really helps, no air in the house goes to burn the fire. helps keep everything warm

my stove has a hookup for the pipe already from the manufacturer
Title: Re: Wood stove make up air?
Post by: shinnlinger on December 09, 2014, 11:40:30 AM
My current woodstove is a circa 1977 Defiant knock off, so no air hookup, but maybe someday I will upgrade.  I like spruce bunny's crack the window a bit and see what happens.   Why I didn't think of that is a good question.  I would like to think I built a tight house but who knows????
Title: Re: Wood stove make up air?
Post by: Cornishman on December 09, 2014, 01:18:52 PM
I have a 4" flex pipe going from my stove to the outside, for intake air, it really helps, no air in the house goes to burn the fire. helps keep everything warm
my stove has a hookup for the pipe already from the manufacturer
Very sensible arrangement. Absolutely no point warming air to run the stove.
Title: Re: Wood stove make up air?
Post by: bandmiller2 on December 12, 2014, 07:22:43 AM
Shinn, if you have a Defiant like stove you have that little thermostat controlled door bottom left in back. get a forced hot air floor register duct and even a alum. dryer vent hose to put over the air intake to try. If it works well do it more permanent. As stated if you have a drafty old house no need, new titey house almost mandatory. Frank C.
Title: Re: Wood stove make up air?
Post by: John Mc on December 14, 2014, 08:57:42 PM
get a forced hot air floor register duct and even a alum. dryer vent hose to put over the air intake to try. If it works well do it more permanent.

Don't use the dryer duct for a permanent installation, an dkeep a close eye on it for your trials. Depending on your set-up, chimney draft, wind conditons, etc, it's possible to get a back draft, pulling hot air from the firebox into your air inlet.  It should be made of something that can take some heat.
Title: Re: Wood stove make up air?
Post by: shinnlinger on December 14, 2014, 09:08:57 PM
My stove does have the thermostat thing in the back and that is an excellent suggestion.  THanks
Title: Re: Wood stove make up air?
Post by: bandmiller2 on December 16, 2014, 08:13:09 AM
Shinn, I wonder if you had a sheet metal chamber behind you stove to pre heat the cold air if it would help economy wise.?? Frank C.
Title: Re: Wood stove make up air?
Post by: John Mc on December 16, 2014, 08:47:13 AM
Shinn, I wonder if you had a sheet metal chamber behind you stove to pre heat the cold air if it would help economy wise.?? Frank C.

Either way, the stove is using BTUs to heat up the air, it's just a question of whether it gets heated in the combustion chamber or in whatever preheat method you use. Taking air from inside the house or outside makes little difference unless you've got a really excessive draft: you are heating up the air you use for combustion one way or the other. The one thing that could make a difference is if you are pulling in enough cold air into the combustion chamber to drop its temperature significantly - if the combustion chamber temp drops enough (especially in a non-catalytic stove), the gasses won't burn off, resulting in a lot less BTUs generated.

A lot of the newer, really tightly built homes have powered ventilation systems in them (to provide a healthy air exchange and reduce condensation in the home). If properly set up, these ventilation systems provide plenty of fresh air, thus no need for outside air for combustion on that score. (When the power goes out here, I just crack a window slightly, if I notice the wood stove not drawing properly.)
Title: Re: Wood stove make up air?
Post by: petefrom bearswamp on December 20, 2014, 10:03:08 AM
I have an outside air intake for my oil boiler consisting of 4" plastic with a trap similar to a sink trap to prevent back draft.
I can feel the outside air coming in when the furnace runs.
I put an air exchange system in 14 yrs ago stopped using it after 2 winters, took it out this year, didnt like it.