Barrel Stove variation questions.

[WoodstoveWil]

Hello gents.
I've been looking around this site for ideas on wood stoves, specifically barrel in barrel types. I grew up with a double barrel in the basement of my parents house so I'm familiar with that, but wanted to move the stove outside for insurance placation. I'm in an older farm house with propane and it chews up the pay check pretty quick (thermostat is never above 60) so I'm trying to get wood heat going. If I go with a double barrel setup I would have to build an insulated shed around it, which would not be a major thing but the ground is frozen already.

Bring around the idea. I have seen plans for barrel in barrel setups using a 20 gallon barrel inside of a 30 gallon, the two being placed inside a 55 gallon drum with insulation between the 55 and 30, and an air pocket between the 20 and 30. The drums were vertical and air was forced through the air pocket to heat a garage.

Because I already have many 55 gallon drums around the farm as well as an old empty 300 gallon tank, my thought was to replicate that idea on a larger scale.

Initial thoughts are:
Cut open the 300 gallon tank and burn/clean the interior.
Spray foam insulation around interior of the tank
Install the 55 gallon drum in the center of the tank.
Run 8" steel pipe (on hand) from the 55 gal. out above the 300 for a chimney
Install cold air return on the bottom back end of the 300 gal with a sheet metal baffle forcing the air to travel to the front of the tank and across the top to the hot air duct installed at the top back end

What I'm trying to figure out is how to automatically regulate the fire box (forced draft), and whether or not the foam insulation would stand up to the heat.

Any thoughts or ideas?

 

[homebuilt burner]

I believe with an outdoor burner the draft is controlled by an aquastat. I built a forced air corn furnace and controlled the draft and feed auger with the house thermostat through a relay. And the air circulation fan with a fan stat. So, basically when the house thermostat called for heat the draft fan comes on and stokes the fire until the house is warm enough. The hot air circulation fan is independent and just blows when the heat around the burn chamber is hot. It worked very well for me. On a wood burner I think it is important to totally shut the draft fan opening and the fans used on outdoor boilers have a gate that blocks off the fan when it is off.

 

[WoodstoveWil]

That makes sense. I have been thinking that I could control a draft fan with a separate thermostat set a degree or two above the house temp so it would stoke the fire ahead of the blower fans coming on. If I gather correctly you are saying that if I run a forced draft fan to the house thermostat it would kick on stoking the fire and heating the air around the barrel, and once that reached a certain temp it would activate a separate thermostat connected to a blower fan. Am I right with that?

 

[Ironhorse74]

It really boggles my mind that anyone would screw with a barrel stove given the price of a used EPA Phase II stove that will not only be hotter it will use much less wood and be safer. Especially given that the chimney costs the same.

WOW

Brad

 

[WoodstoveWil]

Just trying to do the best I can with what I have availabe. There is no conventional masonry chimney involved, simply a piece of 8" solid steel pipe to clear the air pocket followed with single wall pipe.

 

[homebuilt burner]

yep, I think you get the idea. But, keep in mind the blower fan stat will probably end up being set at like 115 or 120. This will be something that will take a fair amount of "tinkering" before it gets dialed in. Are you the type that is ok with that?? You could either use a line voltage thermostat to control the draft fan or run the 24 volt signal through a relay, I ran mine through a relay.

 

[aka Larry]

It really boggles my mind that anyone would screw with a barrel stove given the price of a used EPA Phase II stove that will not only be hotter it will use much less wood and be safer. Especially given that the chimney costs the same.

Do you have a cost and link to this magical EPA Phase II stove?

 

[gungatim]

I have an idea for you, based on an outside wood stove I bought about 5 years ago.

it is called the lil' house heater from outsidewoodheater.com. the guy makes them by hand in Missouri. I bought 2, one for me and one for a friend. they were around $1500 then.

I have a regular woodstove inside but used this on the house a while before moving to the shop. I use them both, inside for a night, but the outside one if I'm going to run it for a weekend or several days (needs longer to get started, heat up, uses more wood initially, so not efficient for a 4 hour fire).

so heres the scoop: when I got it, I kind of took it apart to see how it's made.

it is about 3/4 of a 55 gallon drum, he cuts off maybe a foot of the open end. it is mounted horizontially within an angle iron frame. the front he welds up a sheet metal plate and door with a manual draft.

inside the frame it is insulated with what looked like fiberglass insulation board. it is sheathed with aluminum trim coil pop-riveted to the frame, the flue comes out the top (std. 6" stove pipe).

on the side of the bottom is a smaller box made the same way housing an off the shelf blower. on top is the heat take-off, same ducting setup, like 8x12 roughly. inside that is a temp sensor (again off the shelf parts) wired to the blower. when the stove heats up enough, the blower turns on/off automatically.

the theory is you run the blower intake (insulated flexible duct from hardware store) through a window at one end of the house, and run the heat duct in through a window at the other end (so you mount it outside near a window, I just used foam taped in the window opening to mount it).

since the barrel is sealed from the enclosure, there is no smoke, just the heat being re-circulated throught the house/building.

it would be easy to build one yourself if you have the skills.

it works really well, and is pretty good on wood usage, almost anything will burn. you just get the fire started and adjust the draft manually. if it gets too hot in the house, open a window...

just thought I would share, not trying to take any business away from the guy (it's actually a pretty good value), but it's also not that complicated a setup.

here's a pic from his site:

 

[homebuilt burner]

Another thing I was going to mention, don't be afraid to put some fins on the burner chamber. I could not believe the difference in the heat out put.

 

[aka Larry]

Another thing I was going to mention, don't be afraid to put some fins on the burner chamber. I could not believe the difference in the heat out put.

Example? I have a double barrel stove and could modify it.

 

[homebuilt burner]

I built a corn burner a number of years ago and the main chamber was 20"roundx30"tall. I had the local metal shop shear about 200-1 1/2" x2" tabs out of 14 gauge and welded them onto the chamber, that alone made a night and day difference in heat out put. On a barrel stove I would suggest rings around the barrels, kind of like an air cooled engine cylinder.

 

[WoodstoveWil]

Thanks for the suggestions. I've picked up some of the parts needed to get started so if work and weather allow I'll be going about it this week. I'll throw some pictures up as I progress. I'm not opposed to tinkering with it for a while to get it right.

 

[Ironhorse74]

Do you have a cost and link to this magical EPA Phase II stove?

Every wood stove manufactered since 1994. Litteraly hundreds of thousands. Plenty of information out there but you can start with my old buddy Tom. https://www.chimneysweeponline.com/fswood.htm

 

[dfiler2]

I didn't see this answered but your one question, the foam will not stand up to the heat. I see it a few times a year where someone fires a boiler with no water, the foam burns off completely very quickly. Fiberglass is probably going to be your best bet.

As far as controlling the heat I think I would play around with a surface mount limit switch (snap disk) and a solenoid to control the draft. Years ago I built an indoor wood furnace and used the choke spring off of a car to control the draft.

 

[Bondo]

Initial thoughts are:
Cut open the 300 gallon tank and burn/clean the interior.
Spray foam insulation around interior of the tank
Install the 55 gallon drum in the center of the tank.
Run 8" steel pipe (on hand) from the 55 gal. out above the 300 for a chimney
Install cold air return on the bottom back end of the 300 gal with a sheet metal baffle forcing the air to travel to the front of the tank and across the top to the hot air duct installed at the top back end

What I'm trying to figure out is how to automatically regulate the fire box (forced draft), and whether or not the foam insulation would stand up to the heat.

Ayuh,.... Here's My take on yer plan,....

Put the insulation on the Outside of the big tank,....
No way it'll get burnt up that way,....
You can then cover it with whatever ya want to keep it dry, 'n protected from the elements,...

For controllin' the draft,....
Get yerself a "Stack Switch", for a hot air furnace,....
It's nothin' but a temp switch for air, rather than an aqua-stat for water,....
Ya might need 2 of 'em,...
One to control the draft, 'n another to control the fan that moves the heated air,....

 

[dreasoner]

Why not use a fan/limit controller from a furnace. The fan and off settings control the circulation blower. The limit is wired into the combustion blower circuit as a hi limit safety. Should be able to use some sort of a variable or step controller to operate the combustion blower.

 

[homebuilt burner]

dreasoner is right. I kept saying fan stat but it is actually called a fan limit switch.

 

[CNGsaves]

While you're fabbing up the barrel stove from scratch, might consider adding copper tubing with water so you can get from free hot water while you're at it !!