7075 aluminum wood burning stove!

[gabigowriel]

Hello everybody!
Could a wood stove be manufactured out of aluminum 7075 , CuZn15 or other good thermal conductive material?
If so please share your knowledge with me!
I was thinking of building a wood stove , better and more efficient than a normal cast iron or steel one!
Thank you kindly in advance!

 

[cloa]

Have you considered the effect of the difference in thermal mass from using other metals will have?

 

[stanweld]

Ever toss an aluminum can in a fire? There's nothing left in seconds. Oxidation will destroy your wood burner quickly. My uncle once did this in the '50s - a resounding failure. Also the temperature of the fire can be near the melting point of the aluminum.

 

[gabigowriel]

@cloa : No , I haven't considered that; I just "went" for a material that theoretically had a good thermal transfer value and thought that was good enough!
That's why I'm around here asking questions and advices , or even maybe someone tried this before me!

@stanweld : No, I didn't put an aluminum can on a fire; I usually don't drink and if I do I prefer a good wine in a reasonable quantity(a glass or maximum two, after wich is "good night" for me!).
I've seen the effects of oxidation in a cast iron stove and it's one of the reasons why I got on this forum and started to ask questions about a better heat transfering material for a wood stove and better resistance alloy to these kind of things!
I thought the high temperature resulting from burning wood(without a second burning chamber with the help of air from outside through pipes), will be present only in the bed of fire , not in the rest of the stove+ if using a good heat transfering material , it would never get past 400-500 degrees Celsius!

So bottom line is that aluminum alloys are not suitable for this aplication despite the very good heat transfering properties...
Maybe an aluminum radiator with large surface area on the OUTSIDE of the stove would do the job?!

And the stove be made out of CuZn15 brass?
From what I've found this material/alloy has a melting temperature around 1005-1025 degrees Celcius and a thermal conductivity of 145-145 W/m.K!

http://www.matbase.com/material/non-ferrous-metals/cast-copper/g-cuzn15/properties

I've seen a coal stove user/owner that has put a lot of aluminum radiators on the stove and the results were quite promising despite the actual stove beeing made out of steel sheet and not cast iron wich many claim is a lot better!
Either way, I have to build one stove until the next winter or buy one although I've been in MANY stores so far and none convinced me of their quality or performance...
Also, in using CuZn15 sheet , another big problem would appear on how to weld the brass sheet together in a square or rectangular shape in order to give it the appearence of a classic stove!
Anyway, thank you so much to all those willing to answer my questions on this forum!
Bye for now!

 

[btrueblood]

The zinc will boil out of the brass alloy. And any copper alloy will corrode over time due to trace sulfur in the wood.

Tungsten would be a lovely woodstove material, if you could put a plasma-spray coating on it to reduce oxidation.

Then again, grey cast iron is pretty conductive, and an oxide coating on the inside would work there too, maybe a good ceramic glaze on the outside to keep it looking pretty. In fact, it's such a good idea, that you can find them in stores now.

If you want one that will last "forever", make it out of Inconel 625 sheet, say 1/16" thick or so. From experience, you could beat on the darn thing while it's red hot, with a cast iron skillet, and it won't hardly even dent.

 

[gabigowriel]

@btrueblood : well, I guess that's that regarding wood burning stoves...
I'll buy a good one and problem solved!
Making a wood burning stove from inconel 625 is very expensive; I've studied its data sheet , a guy from USA that works every day with this material quated me with a price and it was very expensive!
It's like buying a formula one car just to cut the grass in front of your house...
Maybe a cast iron stove with lots of aluminum radiators on the outside will be enough!
After all, I'm trying to heat about 70 square meters of my home(the rest of 40 square meters are not used in the winter).
For a single guy would be good enough!
Thank you all , I wish you a wonderfull day and this topic can be closed or, if so desired ,left open for further opinions , although I think it's all clear now!
Bye bye!

 

[IRstuff]

70 square meters is a rather huge area for a stove to heat up. Even if it were in the dead center of a square room, the corners of the room would be almost 6 m from the stove; it'll be even worse if it's located along an edge or in one corner. So, it's not the iron conductivity that's the issue, it's the air circulation.

The images of toasty warm stoves with people gather around it are misleading. I would guess the effective radius of heating without forced convection is probably around 3 meters.

TTFN
faq731-376

 

[stanweld]

The house in which I lived in Scotland had a steel coal burning stove for primary heating. It had stainless steel water tubes to heat water that was used to provide heat for the wall mounted radiators. Did an excellent job. It also had a fan mounted for convection heating as well as radiant heating.

 

[Guest102023]

The conductivity of the steel stove wall is not a significant barrier to overall heat transfer; in fact I suspect it is quite miniscule. And as mentioned, aluminium will deteriorate rapidly.

A properly functioning wood stove gives off most of its heat by radiation anyway, so you are better off applying the appropriate surface conditioner (black). Contact your local stove retailer for info. And dry your hardwood for one year.

 

[Compositepro]

If you want to build your own wood stove, there is no better design than a barrel stove. There is plenty of information on the internet. They work great. You can get inexpensive kits. I prefer to used an open head drum so that large logs can be put in. This saves tremendous time and labor on splitting wood and the stove will burn through the night.

 

[ornerynorsk]

Do not build a woodstove from anything other than ferrous based metals. Not unless you have very good insurance that will kindly overlook the fact that the stove is made from material that has a melting point several hundred degrees F less than a well-stoked wood fire. I'be burnt wood for a dozen years or so and it's no great feat to get the chimney pipe and fittings glowing red.

As to the barrel stove comments, they will not be allowed in a residence under most insurance plans, as they burn out rather quickly (not enough thickness to prevent rapid oxidation). Due to the thinness of material, you also don't have enough safety factor should the air vents be left too open for too long a time (think chimney fire).

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[moltenmetal]

My wood stove not only is made of steel and cast iron, but it is also lined with hard refractory (i.e. firebrick).

...and even those firebricks don't last forever.

Don't mess with non-ferrous materials. You need something which not only is high melting, but also which retains a fair bit of strength at high temperatures.

Also be careful about cooling the flue gas too much in an effort to extract more heat from the combustion. Normal wood combustion generates volatiles which are not completely combusted, especially in the early stages of a fire and when the wood is not perfectly seasoned. These volatiles can deposit inside the flue and on other cool surfaces at even modest temperatures as "creosote", and can accumulate and later lead to a chimney fire.

 

[gabigowriel]

@moltenmetal: I did some more "research" and for a better combustion of those gases this video "should nail it":
Secondary Combustion Explained.wmv

http://www.youtube.com/watch?v=qvc79F1pR08

But yes, I made up my mind: steel is real