When it comes to heating a room or house in the dead of winter, who are we to argue with Canadian lumberjacks?*
Developed by Canadian lumberjacks in the snowy Rocky Mountains, the enclosed heating chamber is built for practicality, quickly and cheaply warming cabins while using readily-available materials (in lumberjacks’ case, of course, that would be wood). The Bullerjan Furnace works independent of oil, gas and electricity, torching wood to provide your space with heating. When used, air moves from the bottom to the top vents, distributing the heat in a fast and even manner.
As with the Lumberjacks, my need for a better heating method for my workshop arose on a cold winter day. It was nearly -30 degrees Celcius (-22F) that day when I decided to go and work on a project. As I entered my workshop and flicked on the lights something strange happened. It was so damn cold that even my fluorescent lights would not turn on properly. My fingers got numb in just a few minutes without hand gloves - woodworking that day was not pleasant! Heating my small shop with the old wood burner would have taken at least half a day. This is when I realised that I needed a better heating method.
I got a sign later that week when scrolling through Pinterest and stumbled upon this photo. It became the main inspiration for my stove design. I liked it because it had square tubing welded at angles instead of bent round tubing like the original Bullerjan. This was something I could easily replicate in my workshop with the tools I had.
I would not consider myself to be a good welder. I am just a guy who can in most cases can make two metal pieces stick to each other but it will probably not look pretty. In fact, I would sum up my welding knowledge with a sentence " I know it is hot but I will still touch it to be sure!" This is also why I assure you that you should not be intimidated by this project. Some welding knowledge would be good before you try to make a Bullerjan stove but you definitely do not need to be a professional.
I have had an original Bullerjan stove in my home for over 15 years. When designing and building a new one I kept a close eye on the original one to make sure it would also work in the end. And as you can see it did.
Disclaimer: There are obviously a few dangers involving this project. Please weld your own Bullerjan stove only when you are absolutely sure you can do it and it would be safe in the end. Use proper precautions when using a wooden heater (fire extinguisher nearby, CO and smoke detector, non-combustible surroundings, common sense, etc). More about safety at the end of this ´ible!
More photos of the stove in the final step!
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Step 1: History of the Bullerjan
The Canadian lumberjack story is great and all but to me, unfortunately, seems like a folk tale. It could be that these lumberjacks used a similar design for a heater but modern-day Bullerjan stove was invented in 1975 by Eric Darnell in Vermont (or so the Bullerjan website claims)
"The history begins in a cold Vermont winter in 1975 with the inventor Eric Darnell. He improvised housing, despite its brand new wood-fired stove would not get sufficiently warm.
At that time, Darnell earned a part of his income through the installation of specially bent steel tubes in open fires in that way, that their heating capacity – without electric blowers – was noticeably increased. For this, he made use of the fact that hot air rises (convection effect). From his knowledge gained here and the analysis of the weakness of his radiation stove, arose the idea for the Free Flow hot air stove. It took only a week from the idea to the first prototype. The heating power was overwhelming. Thanks to the Free Flow, Darnell’s draughty home became equally warm everywhere. Up to today, he heats his entire house in Vermont with a first-generation Free Flow."
The photos are from the official Bullerjan website and showcase Eric Darnell and his first production partners Bob and Sherm Wilson in 1977
Step 2: Tools, Materials and Design
One does not actually need a large array of tools to complete this build but some things are essential. You will need:
- Angle grinder with a variety of chopping, grinding and sanding discs
- Jig saw
- Stick or MIG welder
- Measuring and marking tools
- A few strong clamps
- Wire brush
- Steel square
The list of would-be could-be tools is endless but the best tool is always the one you already have!
All the blades and discs need to be rated for metal!
- 60X60mm rectangular tubing
- 60mm wide flat bar
- mm thick sheet material
- Butterfly damper
- 3-5 cans of heat resistant spray paint
- White spirit and a rag to remove dirt before painting
- 40mm flat bar
- Sheet material
- Large washer
- A metal rod (for the hinge)
- Sealing cord/band for wood burner door
- rectangular metal rod
- 10 cm of 70mm round tubing
- A nail
- A small washer and a spring
- Small piece of sheet material
- A Nail
- Two metal springs from an old bicycle seat
- Small piece of flat bar
- Metal rod
- A large washer
Bear in mind that this is the design I decided to go with. You can alter it or choose a completely new one if you desired it!
An Internet search revealed a diagram showing Bullerjan basic work principles. I have also added it to this step. Unfortunately, I can not find the original source for it, but I got it off of this page.
I designed my stove so that it would fit in my workshop. I have to admit that it came out a bit bigger than I needed but is better to have a heater that is a bit overpowered than a one that is underpowered. But of course, not so powerful that it burns your house down! You can find a Sketchup drawing with precise measurements for the stove I built. The amount of material you need depends on how big of a stove you want. Making a sketch with precise measurements definitely helps when calculating the amount of material.
Step 3: Chop It!
The first step is to cut the square tubing to the proper size. I used my chop saw for this but it could also be done just with angle grinder although it requires much more time and effort. Another way to cut this metal would be with a metal band saw. In every case try the angles first on test pieces and do double or even triple checks to be extra sure.
After all the pieces are cut it is also important to grind all the edges that will be welded. This creates a little space that will be later filled with welding bead. It is important to have it because otherwise when grinding and smoothing out the bead, the joint would just come loose again.
Step 4: Weld It!
It is a great idea to build a jig before actually starting welding. I built one out of some wooden pieces and cheap particle board. It is important to keep an eye on everything when welding to avoid fires (keep an extinguisher nearby). I also added a little groove to my jig exactly where the welding bead would be. This was done to keep everything flat. Talking about keeping things flat - it is a really good idea to also clamp everything down as welding tends to warp material.
After welding, I ground the joints flat with an angle grinder.
Step 5: Weld Some More!
After the square tubing pieces are ready it is time to weld them all together to form the main frame of the body. Lay everything on a flat surface and use a steel square to get the pieces aligned. Check everything before welding!
My frame consisted of four ribs on each side. After the tubes were welded together I added a 60mm wide flat bar to fill the space between the ribs. I built another jig to space the flat bar even distance (1.5cm) from the outer face. Often I needed to persuade the square tubing with a hammer and metal clamps to actually get the flat bar to fit in between the tubes.
Step 6: Welding on the Back Side and the Damper
Now that the stove is starting to take its shape it is time to add a back wall to it.
Lay the main body on a piece of sheet metal and trace it out. Cut it with an angle grinder but be sure not to use an apron made from an old towel or this will happen!
Weld it! After that add a pipe that will let the smoke and gases escape the stove. The pipe has to fit the piping in your chimney! I decided to hit two birds with one stone and used a damper. It is really important to get the pipe/damper location absolutely right on the back wall. Otherwise, you will have problems when installing the stove. I think I checked at least five times before I actually cut the hole and welded on the damper.
Step 7: Making the Flame Guide
Now it is time to add the flame guide. This is required so that the flame would not go straight into the chimney. It extends the lifespan of the chimney and also makes the stove more efficient.
The flame guide itself is pretty much two sheet metal pieces welded in a V-shape and attached right under the hole where the smoke exits the stove. The first thing to do is to cut out both sides and mark the locations of the square tubing. Cut away these sections as well so that the edge of this plate touches the outer wall of the stove. Weld it into a V-shape when both sides are ready. As you can see I did not have a perfect fit so I had to add an extra angle bar.
Step 8: Extra Air Intake Holes
This is something I copied from the original Bullerjan that I had. It is two round tubes with three holes on the side and on on the end. These tubes provide fresh air through the first two square tubes near the mouth of the stove.
The principle, as far as I understand it, is that once the fire reaches a certain temperature you almost close off the main air intake and the formation of wood gas starts to happen. Then the main air intake will take place through these two pipes.
Certain stove designs are, in effect, gasifiers working on the updraft principle: The air passes up through the fuel, which can be a column of rice hulls, and is combusted, then reduced to carbon monoxide by the residual char on the surface. The resulting gas is then burnt by heated secondary air coming up a concentric tube. Such a device behaves very much like a gas stove. This arrangement is also known as a Chinese burner.
The first step is to weld a washer on one end of the tube, then comes drilling. Three smaller holes on the side and one large one in the main body of the stove itself. Next comes the welding. The holes on the side of the tube need to face the direction the smoke will be going.
Step 9: The Front Side and a Hole for the Door
The front side is made in a similar manner as the back side was made. This time, though, you can not lay the stove on top of the sheet material and trace it out. Now the shape has to be measured and drawn manually.
Once the wall is welded it is time to draw the shape of the door mouth on it. It has to be near the bottom edge but not too close so that ash would start falling out when you open the door. Once happy with the shape cut it out using an angle grinder and/or jigsaw.
When that is done as well it is time to add "lips" to the mouth by welding a 40 mm wide flat bar all around as seen in the picture. Cut out one piece at a time!
Step 10: The Door and the Hinge
Most likely the leftover from cutting the mouth of the door can not be used to make the door itself as it will be too tight of a fit. The door has to be cut out from a new piece of sheet metal. Add a rim from a flat bar to it as well making sure the door fits over the hole in the front of the stove.
The hinge is pretty much just two ears welded on to the door and two ears welded on the main body. They are then connected using a rod which has a large washer welded on top. It takes quite some fiddling to get it working smoothly.
Step 11: The Main Air Intake
On with the main air intake!
For this, you will need a small section of round tubing, a small piece of sheet metal, a nail, a washer and a spring.
The first thing to do is to do cut the round tubing to length. It has to be a bit bigger than the diameter of the inner circle. Clean it as well if needed. Use a drill and a drill press to drill a through-hole on the side. It has to be a similar diameter as the nail. My nail was 5mm so I used a drill that was 5.5mm.
Next cut a circle out of some sheet metal. Use the inner circle of the tube as a template. Cut it out exact and use a grinding wheel to get a perfect fit. Well, not a perfect fit but a fit that allows the disc to turn 90 degrees inside the tube without any resistance.
Insert the nail through the holes. As you can see I inserted the nail first and then bent it but it is not really necessary to do it in that order as the head of the nail will be cut off anyway. Plus adding the stopper bead to the nail is also much easier when the spring is not too close.
Once the washer and the spring are fixed by a small bead it is time to weld on the disc. Push in the nail in so that the spring is under some tension and weld the disc to the nail using just a few beads (it really does not need more and it is much easier to do adjustments if necessary). Be sure to pay attention to the orientation of the handle when welding (vertical- closed, horizontal- open)
The spring is there to keep a tiny bit of pressure on the latch mechanism so that it would hold its position and not close off with gravity or wind draft.
When the whole thing was done I welded it to the door near the bottom edge.
Step 12: The Seal and the Handles
Almost every heater has some sort of seal on the door to better control the airflow to the fire. It is also a great idea to add one to the Bullerjan. Usually, the seal is fitted inside some sort of groove to make it more efficient and to prevent it from coming loose. To create the"groove" I welded a little rim from some scrap metal I had lying around. After that, I just added the seal that conveniently had an adhesive backing. I could have probably used a seal that was not so wide.
To keep the door shut and to add some more firewood one also needs a handle and a latch for the door. My first idea was to make a similar one as the original Bullerjan stove has. It consists of just one handle that also acts as the latching mechanism. You can see it when taking a close look at these photos. I was already making it but managed to lose the pieces as I made a long pause in the process. This is when my lazy maker kicked in and I decided to try something different. I came up with this design that uses two old springs from a bicycle seat and a few other metal pieces. The build process is pretty straight forward and can be seen in the pictures. Let me know if you have any questions! The design is not the prettiest as it needs two handles to operate but it does the job and that is what matters.
Step 13: The Paint
The last step is to paint the heater to the desired colour. Of course, this is not a must but it definitely adds a nicer look. I decided to paint my Bullerjan matt black as everything looks much more badass when painted black. And this is also something that the Rolling Stones have been advocating. Definately do not use regular paint. As the stove gets really hot you also need a paint that can withstand these temperatures. I found some spray paint that was rated to withstand 800 degrees Celcius from my local hardware store. I bought 3 cans but would have definitely used at least 5 cans.
Before painting it is also important to clean the stove with white/mineral spirit to get rid of any dirt and oil. This helps the paint stick better.
The painting itself should be done in a well-ventilated area with proper lung protection.
Step 14: Safety
Safety talk is something that can not be ignored
As you can already guess there are certain dangers involved with wood burners. To minimize risks one has to undertake some safety procedures.
- First, have a fire extinguisher nearby. As you can see I have one right behind the wall.
- Secondly, install smoke and CO detectors. Smoke is something you can see but CO2 is not. Both are equally deadly! Follow the instructions when installing these detectors.
- Thirdly, keep an eye on the surroundings. Install fireproof material to the walls and floors that are near a heater. In my case, there is fireproof material on the back and side wall and I also installed a thin sheet metal under the stove and in front of the door. It is really important to have it since burning coal might drop out when adding firewood.
Wood heaters might also play jokes sometimes. Mostly when the chimney is cold and the draft is not working properly. In this case, the stove might start to work in reverse puffing smoke in from the air intake hole. This can also occur when there are strong winds outside or the stove has not been used for a long time. This is something you just have to take into account. Keep an eye on the stove for the first five minutes after lighting the fire. Let it suck in as much air as possible to get the temperature up in the chimney to get the draft going. Once the stove and the chimney are up to heat it is impossible for it to start puffing smoke in unless of course Santa Clause gets stuck in the chimney.
My experience has shown that every wood stove (also the store-bought ones) act weirdly on the first few times. It is usually caused by the fact that the stove just needs to "settle in". There might be a lot of smoke so be sure to open all the windows.
Step 15: The End!
This is it! I know it looks like a really complicated project but once you break it down into smaller parts it is quite easy actually. And do not rush it - it took me 3 years to finish this project. Of course, not because it took me so long to weld but because I had countless other projects to work on. But now it is ready and it is mostly thanks to Instructables Metal Contest 2019. It made me finally pull myself together and finish it. It has taken me a lot of effort to document and present this project to you so I would be tremendously happy if you voted for me in the contest! Many thanks!
I know I probably did not explain everything as clearly as I could have so feel free to leave your questions in the comments. Also, leave your thoughts about this project down there. I would love to know what you think!
NB: Making your own wood heater from scratch could be really dangerous so do it at your own risk!
Grand Prize in the