My outside warm air shop furnace.

[nh-rob]

I have had an idea about building this stove for a few years now and finally got around to giving it a try. I had a wood stove that I bought many years ago to heat my work shop. It is a box type stove that has a liner around it and a blower on the bottom with a 7" duct opening on the top. I think I paid $100 for it used way back then. I had used it in my small shop for a couple years but when I change the shop layout it had to come out. My dad gave me his old pellet stove and it is nice to run but does not put out enough heat for my shop wich lacks insulation on the walls. My son has a project that will need painting this winter and a fire even in a pellet stove is not a good way to heat so it got me to start this build.
I started with a used 275 gal oil drum. I used my sawzall to cut the tank in half. I then slid the stove inside the tank and cut out for the chimney pipe, upper duct and lower duct. the blower motor was removed and a elbow was fabricated in its place. I then insulated around the stove and cut out a end cap from the rest of the tank and bolted it in place.
I used flex duct to feed incoming air from the shop to the stove and rigid steel duct with insulation over it for air leaving stove.
I have done three burns with it so far and have been pleasantly surprised how well it works. I would like to install some sort of a heat dump incase the blower quites or we loose power (not common around here). I did install a T were the top duct comes out of the tank and could put a removable cover over it. Right now its just covered with insulation.
Here are some pictures.
View attachment 280597 here is the basic stove

View attachment 280598 this is a view of the ducting coming off of the furnace

View attachment 280599 as you can see there is snow on the ducts and this is with the shop at 70 deg and outside it was 16 deg

View attachment 280600 a view of the fire creating the warmth

View attachment 280601 the spot in the shop where air comes out as you can see no insulation on wall.

More pics next post

 

[nh-rob]

more pictures

View attachment 280616 this is a view of the blower attached to the wall. I have it in a section different from the air coming in so that we can block a warm spot to paint and not suck paint fumes into heat chamber.

View attachment 280617 You can see the stack in this picture. I would like to switch over to a insulated chimney when money allows. right now it is hard to keep at a good burn temp without the air coming out of stove being too hot. I have to keep the draft almost open to get the indicator at a good level and I am seeing over 200deg coming into the shop. Do you think a insulted chimney would help here? I dont see smoke coming out of the stack just heat waves.

 

[dave_dj1]

Looks OK. How do you regulate it? Mine has a little motor hooked to a T-stat that lifts the draft door and then closes it when shop temp is reached.
Of course that doesn't help when the air chamber is hot and the blower keeps running. I usually end up having to open a window if the outside temps rise too much.

I think insulated chimney is a must or you will have tons of creosote in really cold weather.

 

[nh-rob]

dave_dj1 right now I just use the draft and size of fire to control the temp. If it is too warm out I will just use the pellet stove.

 

[Rio_Grande]

Similar to what I have had in mind for years.