Stove technology,efficiency new materials for a stove!

Hello everybody!
I am from Romania ,am new around here , and ended up on this forum after viewing a video regarding "Tending a Hand Fired Coal Stove" wich belongs to Ashcat743
http://www.youtube.com/watch?v=lTsY5eGQ ... ture=inbox

I was looking for a better ,more efficient and cheaper way to heat my home of around 115 square meters (about 1237.849 ft²) , right now using central gas heating with a SaunierDuval 24 kw gas burning "thing"...
I called this way because in december 2011 the pump failed , it cost me around 300 dollars with installation from a authorized guy, in the summer of 2010 the heat-exchanger failed too, so I guess I'm sick of high gas prices , high priced parts and the need for some guy with experience in this domain!
So, to the point:
A coal stove must be made ONLY out of thick cast iron or thick steel sheet?
Isn't there another way or other materials to increase the efficiency of burning coals?
From my calculations , 1 kg of anthracite(the best coal...) contains around 8200 Watts almost close to 1 liter of gasoline wich theoratically contains 8800 Watts!!!!
The only "small difference" is that gasoline per liter costs in my area about 5-6 times MORE than anthracite!
That's quite a gigantic difference...
I was looking for materials to build your own stove and this is what I came up with:
"INCONEL® alloy 600 (UNS N06600) Ni 76.0, Cr 15.5, Fe 8.0 High nickel, high chromium content for resistance to oxidizing and reducing environments; for severely corrosive environments at elevated temperatures. Good oxidation resistance to 2150°F. Good formability.
Furnace muffles, electronic components, chemical and food processing equipment, heat treating equipment, nuclear steam generator tubing.

INCONEL® alloy 601 (UNS N06601) Nickel, higher chromium content for better resistance to oxidizing and reducing environments; for severely corrosive environments at elevated temperatures. Good oxidation resistance to 2200°F. Good formability.
Instrument probes, furnace muffles, electronic components, chemical and food processing equipment, heat treating equipment, nuclear steam generator tubing."
http://www.hpalloy.com/alloys/hightemperature.html
Since in Romania I don't think I could find INCONEL sheets for a custom stove , I'll ask you , those in USA that probably have more of this stuff , how much would it cost to build a cube stove of 50 cm from this material?
I got to the conclusion that a coal stove (or any other stove) should be made out of thin sheets(let's say 1 mm thick) for a better heat dissipation in the air surrounding the stove and thus a faster heating of the space/room!
In many videos/reviews I've seen the "stack temperature" of exhaust gases beeing around 150 degrees Fahrenheit or 65 degrees Celsius!
Converting that heat to Btu's wouldn't that be a loss and thus a decrease in the efficiency of the stove?
After all, this is what we're talking about when using coal in stoves or even wood wich is even lower in calorific value even when dried for 2-3 years!
From my point of view heat should be transmited to the environment to heat as good as possible!
And I know that hot air raises and cold air tends to "sink" but this "problem" could be overcomed with a good centrifugal backward inclined fan wich has a non-overloading characteristic once reaches the maximum speed and the "suction" capacity/Mpa or air depression is quite high(I'm using one of 2200 Cfm in a electrolitical galvanizing process and it really "sucks air").
The remaining exhaust gases from burning coal would be managed by that fan creating a really big draft ,and the advantages would be more heat inside the house and less out the chimney , and so a higher efficiency of the stove(be it cast iron or "high tech" material/INCONEL).
This topic is just an ideea of mine , and I really hope those with more experience to clear things up for me because if not this season the next one I'll SURELY use a coal stove for heating the house be it cast iron, steel , stainless steel or "other" exotic materials!
I'm sick of beeing robbed by the gas company and the house still "sort of " cold!(there is room for better, that's why I insulated the whole "thing"/house 2 years ago with 50mm of polyester and the ceiling with mineral wool the same year).
Thank you in advance and have a wonderfull day!
Bye!
Gabriel.

Materials like the various Inconel and Hasteloy alloys would cost a small fortune, and would be a major overkill.

Definitely not cost effective.

Where I work, I just got a quote for 1.25" Dia. x 15" Inconel or Hasteloy Threaded Studs for a high temp application. There were somewhere in the ranges of $500-800/EACH. Nuts were around $200/ea. and we need 64 studs and 128 nuts!

OK Isayre , these alloys tend to be expensive but they are beeing used in industrial furnaces , so there must be something "good" in them!
Anyway, does anyone used stainless steel for a stove?
Can it handle the heat and probably the gases resulting from burning coal?
Thanks!

@WNY , oh boy...
so it's that expensive INCONEL?!
Any sugestions for what kind of stove to use for a 115 square meters house?
Or maybe 2 or 3 smaller stoves placed "strategically" in the house to replace the heat that would otherwise come from the central heating radiators!
For that space how many Kw of heat would be required considering the insulation made some time ago?
I found in a place some detailed indications and sugestions regarding coal stoves(Internet is a true BLESSING these days... I'm sorry I didn't "get it" sooner...).
http://www.videointerchange.com/coal_stoves.shtml
Here it says so:

"Tips on Purchasing a Coal Stove

Purchase a stove that has the capacity to easily heat the desired space. The fact that this takes position #8 is not to mean it's of little importance. The reality is, that too small a stove, and you'll be too tempted to over-temp it to stay warm ... The lure of keeping warm when the outside winds are howling and the outside thermometer reads a number that could have been recorded in Antarctica, and you will be too tempted to over-temp the stove. Far too many times common sense has taken a back seat to shivering and trying to stay warm. Get one with enough BTU output to do the job....

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!

Expensive materials ? Forget about it !

Just go to your local Junkyard, whether Romania or Timbuctu, get yourself a cast iron drum from a rear wheel truck it will do the trick !
It's thick and heavy, so it will hold heat, and when and if it goes bad, just spend another 10 Dollars and go get another one, better yet, buy two to begin with, so you already have a spare !
and if that's not enough, a tank of a good quality hot water heater will work as well, find the ones that are glazed at the inside. Ther are referred to as " Glass lined hot water heaters "

As far as material to combat corrosion, it's simple, but remember marketing and manufacturing don't like simple, they want expensive so it has higher perceived value.

So you need to figure out how to glaze few sheet metal pieces, it's the process of having ceramic over steel, just like the inside of washing machines, and the inside of high quality hot water heaters, ever wonder why some washing machines last over 50 years with no corrosion ?

And by the way, I think it's Watthours, not Watts, as far as your calculation , Appliances are rated in Watts ( for power ) , energy is rated in Watthours

Currently, most American made stoves are made of plain old rolled steel, except for parts like doors, and grates and few others, and they last 30 plus years if properly used without over firing !

Good luck !

Hello gowriel, welcome to the forum.

The thick steel in our coal stoves works well for the reason that this is a slow STEADY heat.. the coal fire is always burning, so once the stove body is up to
temperature, it stays there.
There is no need for a rapid heating of a lighter steel box/heat enclosure, since the fire is always burning..

The only exception to this is the regulated fire in a stoker stove, and even in this situation, the the ramp up time from an idling fire, to a full fire still allows
for a .125" or 1/8" or 3-4mm thick steel box to heat up as quickly as the fire increases.

I used a lower grade stainless steel for a big hand feed boiler I built, but it was not for the heat transfer abilities, it was for the low corrosion characteristics.


The thin heat exchangers in a gas or oil fired device are thin for the very reason that you mention: rapid heating and transfer of heat to the surrounding air.
When the flame comes on, you want as much of that heat to be transfered or exchanged as fast as possible, but our coal fires are always burnining, so the exhanger box never goes 'cold'.

Just currious, how much does a ton of anthracite cost in your country? How about a ton of good Bituminous coal??

Thanks for the ideas..

Greg L

Glad to see you signed up here, Gowriel! Many knowledgeable people here will have you burning coal next winter, at the latest.

Greg, gowriel had told me in Youtube comments he can get anthracite for $300 per 1000 kg, which works out to just under $300 per ton. (I hope he meant dollars and not euros, although even if euros, coal would appear to be cost effective for him.)

Gowriel, do people use anthracite for home heat in Romania? If so, there are probably used (or new) stoves available much more cheaply than you could build, but certainly more cheaply than building with exotic materials. Those prices WNY quoted would take a LONG time to recover.

Also, tell us more about the wood stoves you have (tile?), and what your options/plans are for chimney/exhaust gases. Are you in a freestanding house, or in a flat?

Again, welcome!

@CoalUserWannabe Well , I'll go look for that cast iron brake drum although today at 12:00 there were minus 7 degrees Celcius so at night will be minus...
Nevermind in the morning...
I promise you , I'll try your version too!
Every ideea is welcomed ,a good brainstorming is always usefull

@ LsFarm :
So there are stoves with thin metal sheet to maximise heat transfer to the surrounding air!
I knew it was a good thing!
I agree with you that thick metal stoves heat up slow but when hot stay that way,but a percentage of heat goes out to chimney although I suspect is not that much...
I like to believe that in any domain there is room for improvements!
Especially in the field of energy!
I "spotted" a metal box made out of steel 8 mm thick in a friend's backyard , went to his place just half an hour ago but wasn't home!
It's 60cm/80cm/50cm so it should be good for "experiments"; all it needs is "the front side" a chimney , an ash pan AND a grate to place coals!
Guess I'll be busy tommorow
As for anthracite coal I recently found one supplier with 1000 RON or 298 dollars!
Bituminous coal I have no ideea, because I haven't looked for these kind of things(commodity...), but I'll try to find out!
I'll guess it's less than 300 dollars!
I did find petroleum coke with a calorific value of 7800Kcal at 235 dollar one ton!
These fuels are still "cheap" because many don't care and pay for gas out of commodity!
My case is an isolated one and I suspect many have no ideea that anthracite has a calorific power almost as big as for 1 liter of gasoline wich is 8800 Watts/hour!(or something like that...).
I have measured "things" once again and I'll have to have 3 coal stoves in different locations, can't do otherwise...
So I'll probably have the oportunity to test a brake drum stove(wish me luck at scavenging the truck junk yard ) , a classic thick steel stove and probably I'll try one out of stainless steel , because a stainless steel sheet of 1meter by 2 meters costs about 70 dollars and it's 1 mm thick wich I think it's enough!
I'll post pictures with my progress but it's hard to do anything when it's so cold outside!
Although I have a place/lobby kind of , 20 square meters where it's not that cold but still with a cold air wich is not so good for lungs...
Thank you all and I wish you have "a hot winter" , INSIDE the house!

Ashcat wrote:Glad to see you signed up here, Gowriel! Many knowledgeable people here will have you burning coal next winter, at the latest.

Greg, gowriel had told me in Youtube comments he can get anthracite for $300 per 1000 kg, which works out to just under $300 per ton. (I hope he meant dollars and not euros, although even if euros, coal would appear to be cost effective for him.)

Gowriel, do people use anthracite for home heat in Romania? If so, there are probably used (or new) stoves available much more cheaply than you could build, but certainly more cheaply than building with exotic materials. Those prices WNY quoted would take a LONG time to recover.

Also, tell us more about the wood stoves you have (tile?), and what your options/plans are for chimney/exhaust gases. Are you in a freestanding house, or in a flat?

Again, welcome!

Thanks , I would have probably "wondered around" on the youtube or internet in search of information regarding coal stoves!
Here's the original romanian link for buying anthracite :
http://www.bizoo.ro/firma/diazepam/vanz ... e-Antracit
There are other suppliers wich sell anthracite from Ukraine but they sell only at a minimum of 5 tons once!
Of course the 300 are dollars, actually it's a converting in dollars , because they sell anthracite in LEI / RON our currency and that's 1000 RON divided by 1 USD = 3.3024 RON so it's about 300 dollar one ton of anthracite...
It is cost effective for me to burn coals because our gas company sells us/THE CUSTOMERS gas measured in cubic meters but the bill comes in electric Kw!
They say that for 1 cubic meter of gas you will get 10.51 electric Kw, a value wich NO ONE can verify , and the price of your GAS BILL will actually go up if our government decides to raise the price of electricity(wich will surely happen this year after a very severe drought and the decision to sell electric energy companies to "other investors", wich also happened to our gas company in 2008 and since it did we pay gas calculated in electric Kw and not cubic meters of gas consumed as we used to do BEFORE 2008- "strange" but this happened after 1 year we "were accepted" in the European Union) ...
A very interesting way to steal you and if you don't like it then you can give up to natural gas...
Wich of course many can't do...
Romanians used to burn wood , coal and pellets but commodity and ignorance has driven a lot of them to natural gas...
I found second hand wood stoves but you wouldn't believe what are the prices: it starts from 200 euros and can reach 1500 euros...
But they're cast iron and were made in the 1920-1940's...
New cast iron stoves go for around 700 dollars or more!
I found one out of cast iron for about 140 dollars but it's a 5Kw maximum and I haven't went to the store to "examin it" YET...
Also it looks kind of ugly...
Here's the link for it:
http://www.depozit-online.ro/shop/sobe/ ... 60-dmm-290
As for "exotic materials " for a coal stove , I think I'll drop it dead , and at most try a stainless steel stove and see what's what....
The stoves that are now build look something like this:
http://www.ambrozietera.ro/images/model ... a%2025.jpg
this one is in the kitchen and hasn't been used for YEARS...
Another one is build half in a room and the other half in a bigger room!
It works well because I got "nervous" and fired the darn thing this morning...
The central heating was "working" like hell and still couldn't maintain the temperature in the system above 50 degrees celsius...
One hour of burning gas in this stove "calmed down" the central heating unit
The one build "half here-half there" looks similar to this one :
http://prodnm.infoconstruct.ro/clienti/ ... carmin.jpg
I'll make some photos but my camera has let me down about a week ago, and I gave up the cell phone after getting tired to be found by ANYONE , ANYWHERE , ANYTIME and of becoming concerned with some pains in the part where I used to keep the phone during the day!
I know it seems incredible but I have a sensitivity to mobile phones and my leg , arm or any part of the body where I used to keep the mobile phone , used to hurt for no apparent reason...
Since I gave up the phone everything is fine and the "stress level" dropped like a rock in the sea!

The chimney I was thinking of using the one that is built now, but there seems to be some problems with draft with a cold big cement chimney...
I don't know about that, I'll probably look more into that problem when I'll get to it
The house is freestanding, about 500 square meters with garden and house(10 meters wide and 50 meters long)...
I can do almost everything I want and have no problems with anyone!
Wait untill you get in the countryside
There you can really do what you want and no one says anything...
I'm kind of embarrased to say it but in one village not even police don't "argue" with some individuals or gangs...
20 years ago it was even more freedom, but since Romania entered UE some sort of "dictature" began and even our leaders go with it...
Strange but true...
I hope I won't be considered "off-topic" with this long post...

CoalUserWannabe wrote:And by the way, I think it's Watthours, not Watts, as far as your calculation , Appliances are rated in Watts ( for power ) , energy is rated in Watthours

His reference to Watts (KW) is the metric equivalent to our BTU/hr...3.412 BTUs equal 1 watt...it is all about any source energy/power output and nothing to do with watthours ( electricity used over time).

By the way McGiever :
how much does it cost 1 cubic meter of gas in USA?

If we got into this "price thing" I began to be curios now!
Here in Romania 1 cubic meter of gas costs about 1.3RON and on the bill they say you get betwen 10.51Kw and 10.88Kw!
Amazing thing is that the figure 10.51 value is in WINTER MONTHS , so they give us worse gas , as power just when one needs it most to be powerfull!
The other value is in SUMMER...
So bad gas in the winter and good gas in the summer...
I don't know what to say more...
Who doesn't believe me I'll show them the bills!
ALL of them for the 2011 year!
Take for reference that 1 US DOLLARS is the equivalent of 3.3 RON/lei , our romanian currency!
Also, 1 kg of anthracite costs here 1 RON and a ton 1000RON/lei!
So with 1 US dollar one could buy about 2.5 cubic meters of gas!
I have no ideea how gas consumption is measured in USA and hope you can clear things up!

Here is a start...
1 cubic meter = 35.3146667 cubic feet...or...100 cubic foot = 2.8317 cubic meters

It is priced by 100 cubic feet, I think??? Natural Gas. ... Natural gas is metered in units of hundreds of cubic feet (CCF).

To complicate things even more...Therm Billing

Therm billing is the standard throughout the natural gas industry because it provides consistent billing units as gas flows from the production well to the individual customer’s meter. By billing in therms, a customer pays for the heating value of their natural gas, not the volume of gas used.

The number of therms used is determined by multiplying the CCF consumption by an "energy factor". The "energy factor" is determined from the monthly average BTU content of the natural gas as it is delivered through the transmission pipeline.

1 Therm (natural gas) = 1 CCF x Energy Factor (BTU conversion factor)

Think of therms in comparison to grades of gasoline. A car may get better mileage and use less gas on 93% Octane than 86% Octane. The car’s tank may hold only 20 gallons of gas, but depending on the grade of gasoline, its performance may be more efficient. A higher thermal factor of natural gas means appliances may operate more efficiently and ultimately use less volume.

I have no gas available, and no knowledge of pricing... someone will bring that info...

Take a look at this...http://www.extension.iastate.edu/agdm/w ... /c6-89.pdf

regarding the heat loss due to 150*F exhaust gas temps.....

In my opinion the heat loss is not enough to worry about compared to keeping a reliable draft to avoid CO problems.

A lower stack temp may be OK if you are using a power vent rather than natural draft.

3 stoves sounds like a lot for that sq ft. I guess it all depends on what kind of stoves and house and insulation/infiltration, and how you plan on circulating that hot air. You want efficient heat transfer you do baseboard or radiant.