Stove Technology,Efficiency New Materials for a Stove!

gowriel wrote:@WNY , oh boy...

Too large, & you'll be continuously roasted out (or praying for sub-zero outside temperatures)... Neither will the stove burn efficiently if operated too cool. The fuel will not be completely burned resulting in too many unburned "chinks" and higher emissions.... There are a lot of variables, but a good rule of thumb is to figure on a stove rated at 70,000 BTU to heat a 2500 square foot living space if the building envelope is tight and well insulated, & 90,000 BTU for even typical new construction that has not been surveyed & optimized. (See Below...)"
Accordind to you guys with more experience regarding coal stoves , is this information corect?
Thank you all!

You should do a heating load calc to figure out what stove you need, and figure out the degree days in your area so you know how much coal you should expect to burn. Then get a stove that can put out that +10%. Modern Hydronic Heating is a book you can pick up for around $160. Its got a lot of usefull info.

And as Rob will remind you infiltration heat losses are not your friend and can be worse than conduction losses.

Gowriel, your 115 square meters house (1237 square feet), which you said in Youtube comments is well insulated, can almost certainly be heated with a single stove--no need for three. Your link to the tile stove similar to yours is very interesting--never knew anything like that was made.

There is a helpful fuel comparison calcualtor on this website...https://coalpail.com/fuel-comparison-calculator-home-heating ... that you will find interesting, but you would have to convert the units to metric values first.

Many of us burn coal from a company called Blaschak. Your anthracite supplier uses the same picture of St Nicholas (Santa Claus) on its product! Small world.

HEY....I think Ashcat just found out where all our coal is going overseas and why it's been hard to get in some places here this year!!!!!

Dang, they didn't even bother to change the picture on the label!

Probably started by a Romanian who lived in Nepa and retired to Romania.

Wouldnt surprise me if blashack are investors in the Romanian mining.
https://en.wikipedia.org/wiki/Anina_mine
http://www.eurasiancoal.com/countries/romania.html

@McGiever: So "they're" doing it to you americans too...
With this "gas thing" it's like ordering chicken , eating chicken and paying for caviar...
DAMN...

@titleist : well I thought of a electrical ventilation(backward inclined fan wich I use in a electrolytical galvanizing process to remove gasses and wash them in a wet scrubber) , but that would automatically result in a lower overall efficiency because you use power to generate power; well , a small amount of power to generate BIGGER power in heat value but still , one should consider it as a loss!
Or am I too of a "nerd"?

@ValterBorges : well there is a problem regarding heating and that's why I said there must be 3 stoves(small ones):
the house has many rooms and large "lobby" in wich one enters from outside of the house!
Since I live in only a few rooms I wouldn't have to heat ALL 115 square meters...
Maybe I will if I would need to do so, but since I'm "home alone" for some time, I don't see the need to heat everything...
The 20 square meter "lobby" would be useless to heat...
I "think" 3 rooms, kitchen and bathroom would be enough...
All these spaces amount for half of the whole house or MAYBE 70 square meters
Even so , in the evening I have to choose in what room and bed to sleep
I know what you'll say: the above said are ridicoulous, but believe me at a certain time it was "logical" to have a 115 m2 house...
NOT anymore...
I'll do that heating load calc as soon as I can, than you!
But I took care of these about 2 years ago and I did them well!
To these you are reffering?
" * Ceilings
* Walls
* Floors and Below Grade Space
* Windows and Doors
* Infiltration (air leakage)

No, these are not all the same in terms of their contribution to heat loss. Heat is lost to infiltration and air loss by over 3 times the amount it is lost due to ceilings. These categories generally stack up this way in terms of % heat loss in a home:

* Infiltration / Air Leakage: 35%
* Windows and Doors: 18%-20%
* Floors and Below Grade Space: 15%-18%
* Walls: 12%-14%
* Ceilings: 10%"
http://homerepair.about.com/od/heatingcoolingrepa ... t_loss.htm

@Ashcat : I'll see how many stoves I'll use!
The "temptation" is huge;nevermind the curiosity to see how would perform a thick steel stove , a cast iron "custom thing" and a stainless steel thin sheet stove all filled with anthracite or petroleum coke!
As for the tile stoves you seen in the links , those have been around for centuries I think...
I grew up with those, my grandma had lots of those in her house , and many today still use them!
They are good if you don't have a good insulation in your house!
They heat up like hell and "give the heat" to the air/room slowly!
Just yesterday I helped a friend to make the fire in his tile stove and from about 6-7 pieces of beech wood cut to about 30-40 cm long that could fill one arm/hand the heat was quite something...
But one condition is that the wood must be very well dried (about 2 years in the shade and hot summers...).
And when I think the "theoretically " calorific value of that wood is about 4 kw for 1 kg ,burned at an efficiency of 70% and still get 2,8Kw , I'm "afraid" to see what is like to burn anthracite with a carbon content of 90% or petroleum coke...
By the way: don't you americans feel like the carbon footprint TAX is an imbecility?!
I mean from my knowledge we burn carbon fuels, plants USE CO2 and give us oxygen!
What's the problem in that?!
Plants/CROPS grow bigger, we breath better and MORE oxygen, the brain works better and without that carbon footprint TAX we get to have more money in the pocket...
WHY and what's the use of this TAX?!
After all , water vapours have a much bigger "greenhouse effect" in the atmosphere and thank GOD there are plenty of water vapours "around"...
Anyway :
As for Blaschak ...
OPS , what have we done Ashcat?!
It can't be true...
So you americans struggle to get anthracite at reasonable prices and this company MIGHT sell american anthracite in Romania?!
I can not believe this...
MAYBE it's just a coincidence...
I'll phone these guys from
Zender Srl
Persoana de contact:
Popescu Cezar
Adresa:Str. Arcului, Nr. 20
Localitate:Constanta
Judet:Constanta
Telefon:0752100103
Telefon mobil:0752100103

and just "ask them" where do they bring the anthracite from...
Mind boggling issue...
Well, I have to get going and search for that cast iron drum, look for that friend of mine with the steel box "thrown" in his yard and maybe work a bit too
Thank you all for your responses and have a wonderfull day!

Hello again!
Well , I did manage to do something today:
I found my friend in who's yard there was that steel box and manage to convince him to sell it(not a word to give it away ), and he did sold it to me for about 40 dollars , it's steel 5 mm thick , not rusted at all and the dimensions are 80 cm long, 60 cm height and 60 cm wide an aproximate volume of 288 liters and about 90 kg weight...
After some time just looking at it , I think I can make two stoves out of it
I have a sheet of steel 90 cm by exactly 60 cm and 10 mm thickness wich is somewhere in the bottom of the garden since last summer...
Guess I'll use that plus two 60 cm by 60 cm metal sheet of 6 mm thickness wich I will have to buy tommorow or somewhere this week!
As for cutting , welding and finishing the future stoves I think I'll leave it for some warmer times!
I managed to get a photo camera from another friend and here are some photo's of the tile stoves that are built right now , a photo of the actual steel box bought from that friend of mine , some of the house and two with my dog , a Border-Collie .
I hope things will turn out well with these stoves in the end!
I got to go now , but I'll check the forum later in the evening for "fresh answers" and opinions!
http://i44.tinypic.com/11b2oli.jpg
http://i44.tinypic.com/2hp3gbn.jpg
http://i41.tinypic.com/16s1tk.jpg
http://i43.tinypic.com/1zcnyu9.jpg
http://i43.tinypic.com/t99vzk.jpg
http://i44.tinypic.com/whzbrc.jpg
http://i42.tinypic.com/2w6avdf.jpg

Well now, this is one BIG efficient stove and it has an even more interesting heat exchanger...
It even has convection fins at wich I was thinking these days that they are needed around the fire spot/coal bed in order to lower the temperature and maximise the heat transfer to the environment/air!
Fouday-Poêle

Sounds like you would benefit from a boiler and zoned heating. Hows the price of cooper and or pex there?

I don't know about boilers...
Haven't used one in my whole life
Central heating with gas was around me for the last 12 years...
And before that an gas instant heater for water!(the heating was done by those two tile stoves wich back then burned wood...)
By "zoned heating" you are refering to multiple small stoves or how?
Copper is about 10 dollar for one kg!
If I were to buy copper pipes or other products out of copper the price is a lot higher!
For copper pipe 15mm diameter and a pipe wall thicknes of 1 mm I must pay about 4 dollar for one meter!
If you have any suggestions they are welcomed
I managed to talk to a friend from where I worked a few years ago(gas company) and him and the boss told me they can help me cut and weld the metal sheet and tank I managed to find!
But it's waaay too cold these days to do anything( in the middle of the day 12:00 there were minus 12 degrees celsius , and not even in the garage or their working shop there isn't a good temperature to work/weld anything...).
I'll leave it for a warmer month of the year but in the meantime I must figure out a good design(efficient) for the coal stoves I intend to build and a nice heat exchanger(I don't even conceive a steel coal stove without an heat exchanger!).
Also, I noticed that when lighting a fire and maintaining it in a very good sealed room the draft is very poor when all doors and windows are closed!
As soon as I open the door the fire starts to burn more powerfull!
It's about a fire in a tile stove from a friend of mine!
I was thinking of designing the stove with a 50mm (2 inch) steel pipe welded UNDER the stove and right under the grate for the coals!
The ash pan would be inserted before I start to shake the "thing"!
What do you think?
Is it a good design?
The steel pipe has a big enough diameter to provide ALL the oxygen necesary for an efficient burn?
The steel pipe would be connected in the atic to the outside of the house so lots of fresh air could get to the stove at any moment!
Has this been done before or is an "excentric design" from a romanian?
Here are some more pictures with the 10 mm steel sheet and the metal box wich must be cut in half!
I also talked to a friend of mine about those 2 metal sheets 5 mm thick to complete the stoves(well almost complete...).
I filled the steel tank with a diluted solution of caustic soda to clean all the grease or whatever may have been in it(the friend who sold it to me said he used to wash looots of car parts, machined parts etc... I did found a lot steel , brass and other small sized metal chips and lots of old grease).

Oh boy, where to start.

Your thinking is oriented toward the problems with burning wood. Coal does not burn like wood which is half gas that burns fast and requires large heat exchange area to allow fast clean burn and still absorb the heat. Coal is more like a wood fire that has reached the stage of charcoal, long slow burn.

Heat exchange area is much less critical because there is a long slow burn, provided that the stove is air tight in the area below the grate where air has to enter. Your idea of outside air supply here is good, but not from the attic.

Coal will burn best in a compact well insulated fire box that is deep in proportion to width. Round is best. The proportions of the steel box you acquired are not very good for burning coal. Round and tall is much better.

Your stove design has to start with the grate upon which the coal will burn and through which the air for combustion will enter. This will include a method of clearing the ash from that coal which will be 5 times the quantity of a wood fire. The simplest grate is plain flat cast iron of about 13 mm thickness with slots of the same width. To clear the ash a flat poker is inserted at grate level through slots provided in the stove body and worked back and forth causing the ash to fall into the ash pit below the grate into a pan provided to catch the ash. The slots must be provided with covers to exclude air when not in use.

Next is the fire box or combustion chamber that holds the burning coal. Construct it from castable refractory that you form from a mold. The body of the stove forming one side although it would be better to have it suspended inside the stove body for better insulation which would require a cast iron pot with the refractory lining. The stove body itself could be 3 mm steel. Many American antique stoves are 100 years old with thin steel still good. A study of American antique stoves from this era would help. You might look at the hand fired threads in this forum.

@franco b :
well , I wasn't really expecting to be said that coal burn better in a well insulated box...

You're the first one to tell me that!
I guess I was thinking that coal would burn well in a steel box and that's all...
I'll write down your advices and follow them in the future!
So , that's why many stoves that usually burn wood , don't burn coal well!
I guess I could "switch" the metal box on a vertical position use some thick firebrick pot with a steel suport ,suspend it close to the bottom of the box "give it" some air through the bottom by a 50 mm diameter pipe from the outside(not from the attic; through the attic will just pass the steel pipe) and use a "normal" heat exchanger instead of some complicated "stuff"!
What do you think about wind turbine for creating a better draft through the chimney?
Something like this one in the link:
http://www.smoky.ro/public/galery/B-smoky-67921.jpg
The biggest one(300 mm pipe diameter) costs something like 140 dollars and one for a 110mm diameter pipe about 70 dollars...
I got my mind settled on the 110 mm one + a "valve" to close or open the 110 pipe to regulate the draft created by the wind turbine!
Also, I was thinking at a similar "valve" to adjust the air coming TO the stove through that 50 mm diameter pipe!
I have about 8-6 months to decide on how and what I built out of this steel box...
Anyway : thank you so much for your advices!

Excellent post FrancoB,

So, if you are going to try to build a coal burning stove, you need to start with the grate upon which the coal fire will sit.. Are you going to use a fixed grate that utilizes a poker or 'knife' to aggitate the ash to fall into the ashpan? or are you going to figure out a moveable 'shaker' grate system??

The grate style and shape will determine the size and shape of the firebox, or firepot. As mentioned by Franco, a round pot is better for complete burning and little retention of ash in corners, but a square box is easier to build. Firbrick can be used for a square firebox, or castable refractory is used for a round firepot.

Once you have determined the type and shape of the grate and firebox, then you can start designing the enclosure for the fire, and heat exchanger.

You do not want inaccessable horizontal surfaces because coal has 'fly ash' and it will settle on all surfaces band build up on those nearly horizontal and cause airflow and exchange-of-heat problems..

As Franco mentioned it will save you a lot of wasted materials and time and work to look through the handfired forum for all the info you can find about the shape and design of stoves that function well, there has been more than a century of innovation and experiment already done on the burning of both anthracite and bituminous coal.. if you locate and mimic the tried-and-proven methods and designs, you will have a successful stove project.

Also go to all the websites for current in-production hand fired stoves and look at the cut-away drawings of the stoves, see what is working for the current designs. There is a wealth of informations to access.
I'd google : Hitzer stoves.. Harman stoves.. alaska stoves, DM Machine stoves. I'm sure there are other currently in production handfed stoves. but that's what I can think of right now.

Best of luck with your project.

Greg L

gowriel wrote:@franco b :
well , I wasn't really expecting to be said that coal burn better in a well insulated box...

You're the first one to tell me that!
I guess I was thinking that coal would burn well in a steel box and that's all...
I'll write down your advices and follow them in the future!
So , that's why many stoves that usually burn wood , don't burn coal well!
I guess I could "switch" the metal box on a vertical position use some thick firebrick pot with a steel suport ,suspend it close to the bottom of the box "give it" some air through the bottom by a 50 mm diameter pipe from the outside(not from the attic; through the attic will just pass the steel pipe) and use a "normal" heat exchanger instead of some complicated "stuff"!
What do you think about wind turbine for creating a better draft through the chimney?
Something like this one in the link:
http://www.smoky.ro/public/galery/B-smoky-67921.jpg
The biggest one(300 mm pipe diameter) costs something like 140 dollars and one for a 110mm diameter pipe about 70 dollars...
I got my mind settled on the 110 mm one + a "valve" to close or open the 110 pipe to regulate the draft created by the wind turbine!
Also, I was thinking at a similar "valve" to adjust the air coming TO the stove through that 50 mm diameter pipe!
I have about 8-6 months to decide on how and what I built out of this steel box...
Anyway : thank you so much for your advices!

You do not need to have a thick steel tube, the antique stoves use a fairly thin steel tube above the firepot as a radiant heat exchanger, that is one reason you will find so many round cylinder stoves, it is easy to roll a thin steel sheet into a tube, then attach it to cast iron pieces that form the base, the doors and the top of the cylinder.

Anthracite coal requires a hot fire to start the coal burning, and the hotter the firebox or firepot, the better and more completely the coal will burn. If pieces of coal are against a cool outer steel surface, the pieces will not burn completely, leaving half burn 'husks' of coal in the ash.
The refractory or firebricks reflect the heat back inot the coalbed and promote more complete comgbustion, but the best is if the refractory or firebrick are not inside a cool iron or steel container, but instead surrounded by heat and hot air from the fire.. this will keep the fire burning a a much more efficient high temperature. So a suspended firepot or firebox will not conduct the heat away as much and burn the anthracite to a powder.

Greg L

Read the last posts from Ls Farm several times because it is all good advice.

Leave enough room below the grate for a good size ash pan and it should cover the entire grate area.

Any wind turbine will depend on your chimney, you probably will not need one.

A good stove has two functions. To burn the fuel as efficiently as possible and then to transfer that heat to the room. The two functions are separate and should not happen in the same place. The needs of the burning coal are opposite to the needs of heat exchange. One wants to keep the heat in while the other wants it out.

You can use your box the way it is but the chamber should be a lot smaller. More heat exchange can be added on top. Get a grate first.

Yes you will need a means to adjust the incoming air below the grate, and also a means to admit some air over the fire, usually through the loading door. The door below the grate must be airtight.

LsFarm wrote: You do not need to have a thick steel tube, the antique stoves use a fairly thin steel tube above the firepot as a radiant heat exchanger, that is one reason you will find so many round cylinder stoves, it is easy to roll a thin steel sheet into a tube, then attach it to cast iron pieces that form the base, the doors and the top of the cylinder.

Anthracite coal requires a hot fire to start the coal burning, and the hotter the firebox or firepot, the better and more completely the coal will burn. If pieces of coal are against a cool outer steel surface, the pieces will not burn completely, leaving half burn 'husks' of coal in the ash.
The refractory or firebricks reflect the heat back inot the coalbed and promote more complete comgbustion, but the best is if the refractory or firebrick are not inside a cool iron or steel container, but instead surrounded by heat and hot air from the fire.. this will keep the fire burning a a much more efficient high temperature. So a suspended firepot or firebox will not conduct the heat away as much and burn the anthracite to a powder.

Greg L

Well then , why didn't you said so:
a coal stove is "just" a mini-furnace!
The box out of wich is made hasn't THAT MUCH importance...
The heat must be concentrated around the coals in order for the coals to burn at a higher efficiency, and when it does goes out the chimney , "capture it" and release it in the room to be heated!
Now things are a lot simpler!
Make a "sticky topic" or something to emphasize this very important RULE IN BURNING COALS!