Wood burning stove

[philip in china]

Here in central China it gets a bit cool. I want to make a wood burning stove as there is an almost unlimited supply of free wood here. Does anybody have any plans or advice please?

[JohnW]

Nope, no advice or plans. I've seen a few custome made stoves. Mostly, just some sort of tank with a door added. The feature that really makes my stove (manufactured by Buck) work great is that the stove has a jacket around it and a blower.

You said stove, I automatically assume an indoor stove. Most new stoves around here are outdoor (Hardy Heater is most common) that heat water which is piped to the house. This kills two birds with one stone, hot water and home heating. Outdoor stoves don't even require seasoned wood.

[Glenn]

Buy a fire extinguisher and a smoke detector, before you buy or build the stove.

Always ask what happens to the electrical systems on a wood stove when there is no electric. Buck stove MUST have electric to operate. Without electric, the stove overheats and destroys the fan. The neighbor burned up two fans that way when the electric went out.

The smoke coming from the chimney is a indicator of how well the stove is working. Smaller hotter fires are best, monitor the exhaust temperatures, and get to know your stove and how it operates.

Philip, what is your situation where the stove will be used? Home or shop, free standing or insert, how much free space is available around the stove, the building codes, chimney that will be used, etc etc. Also how much heat do you need? Outside temperatures of zero *F requires more heat than if the outside temp is 40*F.

[rthibeau]

I have made wood stoves used for rendevous and meant to be used inside a tent. It's a matter of sizing the stove to the intended space to heat. Smaller ones use a 3" stove pipe and go up from there....6" to 8" stove pipe on bigger stoves. Basically, they are a metal box, longer than wider, with a baffle plate inside on the pipe end about 1/4 the length of the stove. The door has an airflow control gate and the stovepipe has a damper control also. The larger the stove, the heavier gauge the steel plate to make it. CAVEAT: Most will advise not to build your own stove if it is to be used inside your home, reasons of insurance, safety, etc. By the time you build one suitable for the home, you'd be better served buying one and using that saved time to stockpile your wood.

[HWooldridge]

Two 55 gal drums - laid horizontally, one on top of the other. Bottom barrel is the fire box and is piped to the top one. Top barrel has the chimney at the opposite end from the lower pipe. The heat and smoke go into the top barrel, which then radiates heat into the structure, before exiting the chimney and going outside. If you are real industrious, you can run water pipes thru the top barrel and into a radiator with a fan behind it. A copper coil would work - maybe 3/4" (19mm) pipe.

[Ice Czar]

Info. from Stoves List Participants (exhaustive reference, must explore)


Aprovecho Research Center Advanced studies in appropriate technology
basics
Design Principles for Wood Burning Cook Stoves(pdf)
Designing Improved Wood Burning Heating Stoves(pdf)

Gasification (pdf) New Mexico Energy Mineral and Natural Resources Dept

Biomass Energy Foundation: Woodgas Home Page
TLUD | BioEnergy Lists: Biomass Cooking Stoves
ETHOS Engineers in Technical and Humanitarian Opportunities of Service
Index (base pages) - HEDON Household Energy Network

Then there is the other route
The Masonry Heater Association Home Page - Information on masonry heaters
The Masonry Heater Association Library
MSB Masonry Heater Projects - Sorted

question is how much time do you want to invest, and how clean do you want to burn
and do you want to use it to run a forgefoundry then scavenge the heat into a thermal mass for home heating?
Up-downdraft (Twin Fired) Gasifier for Metal Melting
2.2 Theory of gasification (explore forward and backward as well)

a good place to start is building your own portable cookstove
Instructions for Building the MIDGE (Modified Inverted Downdraft Gasifier)(PDF) out of a few cans
some basic tools and skills in tin can work
Tin Can Chimney
after you prototype a functional solution, figure out where the thermal mass needs to be (clays) where you want insulation, draft, ect. Then look at building something that will last a good long time out of thicker steel and real refractories, with access to a slip roll, welding equipment, forge. Alternately build the whole shooting match out of masonry or refractories.

Image copyright Richard Boyd 2003

[FrogPondForge]

I built a little stove for the kid's fort. It is still in the garage, but I'll test it someday. People have asked for one. I think you can build them for camping, but not in a home. I understand there is alot of money involved in getting EPA certification for in-home stoves for resale. I often toy with building an insert for the house, still a little cautious. Good luck! Mike (Frog Pond's Dad)

[ThomasPowers]

My shop stove design I'm planning to build is based on using two appartment hot water heaters of differing sizes and nesting one inside the other with bottom support and filling in between them with clean dry sand and then welding the "front" on---with a vent or two so the basllasted space is not pressurized in use.

This allows you to make small fast burning hot *clean* fires that heat up the thermal mass that then gives off the heat for a long time.

A heat exchanger in the chimney would help for "instant" heat needs.

22 degF at 9:15 am in Socorro NM

[philip in china]

That has certainly given me a lot to think about. Maybe just an open fireplace with a brick chimney would be a lot less trouble. That might be the way to go initially! Then I could use my time making fire dogs, log box, tools etc. The house fire and carbon monoxide poisoning aspects of it are what worry me most. Here in rural China there are no regulations for anything like this so I would probably abide by the US or British codes.

Please keep the ideas coming!

[Ice Czar]

Maybe just an open fireplace with a brick chimney

Rumford fireplace - Wikipedia, the free encyclopedia
Rumford Fireplaces

however, a masonry heater is far more efficient
Masonry heater - Wikipedia, the free encyclopedia

Take the German stove, for instance - where can you find it outside of German countries? I am sure I have never seen it where German was not the language of the region. Yet it is by long odds the best stove and the most convenient and economical that has yet been invented.

To the uninstructed stranger it promises nothing; but he will soon find that it is a masterly performer, for all that. It has a little bit of a door which you couldn't get your head in - a door which seems foolishly out of proportion to the rest of the edifice; yet the door is right, for it is not necessary that bulky fuel shall enter it. Small-sized fuel is used, and marvelously little of that. The door opens into a tiny cavern which would not hold more fuel than a baby could fetch in its arms. The process of firing is quick and simple. At half past seven on a cold morning the servant brings a small basketful of slender pine sticks - say a modified armful - and puts half of these in, lights them with a match, and closes the door. They burn out in ten or twelve minutes. He then puts in the rest and locks the door, and carries off the key. The work is done. He will not come again until next morning.

All day long and until past midnight all parts of the room will be delightfully warm and comfortable, and there will be no headaches and no sense of closeness or oppression. In an American room, whether heated by steam, hot water, or open fires, the neighborhood of the register or the fireplace is warmest - the heat is not equally diffused throughout the room; but in a German room one is comfortable in one part of it as in another. Nothing is gained or lost by being near the stove. Its surface is not hot; you can put your hand on it anywhere and not get burnt.

Consider these things. One firing is enough for the day; the cost is next to nothing; the heat produced is the same all day, instead of too hot and too cold by turns; one may absorb himself in his business in peace; he does not need to feel any anxieties of solicitudes about the fire; his whole day is a realized dream of bodily comfort.

America could adopt this stove, but does America do it? The American wood stove, of whatsoever breed, it is a terror. There can be no tranquility of mind where it is. It requires more attention than a baby. It has to be fed every little while, it has to be watched all the time; and for all reward you are roasted half your time and frozen the other half. It warms no part of the room but its own part; it breeds headaches and suffocation, and makes one's skin feel dry and feverish; and when your wood bill comes in you think you have been supporting a volcano.

-- Mark Twain (Samuel Clemens)

[jayco]

Philip,we,ve heated our home with wood for many years.
I like heating with wood........but....there is a certain price you pay when you heat with wood, and I,m not talking so much about the initial cost of buying or building a stove and the costs associated with installing a flue or chimney.

If you have experience with burning wood, you already know that you must be eternally vigilant: that stoves, stove pipe,dampers,and the wood itself, can surprise you.

I've been surprised(scared) a few times in my life while burning wood.

Late, one very cold night I awoke to a sound like a train or something and realized I had a cresoate fire in the flue. Luckily, I had an in-pipe damper which I closed quickly.
Our house could have burned that night.

Once when I was just a kid, we had a fire in an open fire place one windy March day.
Apparently, wind came down the chimney and blew sparks onto a cloth chair a few feet from the fireplace. My mother and I were outside and just happened to notice smoke billowing in the house. We quickly dowsed the fire with a couple buckets of water.
To all firemen who read this: yes I now know that our actions were probably not the correct one to take.

Let me sum up by saying there are a lot of hidden dangers to heating with wood.

I've learned NEVER to trust the fire completely, but constantly checking stove,flue, pipe, etc.

I never leave the house or go to sleep with a large fire in the stove.

Be careful!

[Ice Czar]

I too grew up with wood stoves
the kind Mark Twain ranted about, cast iron, supposedly modern (circa 70s before catalytic converters ect) junk IMO, too hot, too slow, prone to wind over pressure, Id walk into rooms and people would start looking for what was burning

the idea of banking a fire and damping it down in an iron stove so it will burn for a long time is so much horse hockey.

What you want is an intense fire that burns the fuel completely, and the heat rather than going up the chimney is absorbed by a large thermal mass.

Many of the posts mention that mass in one fashion or another (water, sand ect) Exactly what a masonry heater Russian Stove (Twain's German stove) does. You might also want to look far closer to home, Chinese Inns used to be built with a large masonry platform that had a fire built under them, a very large communal bed masonry heater, much like a Hypocaust, In Siberia they would build beds over masonry stoves as well.

Phillip, I'll be posting a blueprint within the next month on my Dasifier experiments, the objective is to melt bronze and run a forge. I'll drop a link in here when it's ready.

[Johannes]

hi Phillip,
I have designed a few stoves before, my advise is to make one in masonry, with a metal insert and door (make it arch out it you can this will dramatically improve your draft), and a cast iron grill of some kind te elevate your fire enough to create good air circulation. also an ash drawer under it might be good, be be sure it locks tightly.
If you want I can make you a design drawing, if you tell me what materials and skills you have available.
greetings!

[Glenn]

The amount of smoke exiting the chimney is the amount of cold air entering the room. To make a stove more efficent, use outside air for combustion.

[philip in china]

The point about the outside air is really obvious............. once you mentioned it. I would never have thought of it myself though!