Help with a new project

[blrh93]

here is a picture of a stove i want to build can anyone help me with dimensions?

is a 6" exhaust to big for 3.5"x3.5" riser, ive already got 6" flue system, is twin wall type ok?

the tank is about 10" x 15" with rounded ends, made from steel

im not sure if the chimney should exit  through the bottom or side of my tank

is it ok for the bottom of the j tube to be outside the tank? i guess it just means there will be less vertical distance between top of riser and the exit, will this make a difference to the flow/draw

area of feedtube, burntube and riser is 12.25 sq" 
area between outside of riser and inside of vessel is 48.3 sq", if i put a length of 8" flue over the firebrick riser the area would be reduced to 28.3 sq" would this be better?
area of exhaust/chimney is 28.3 sq"

the chimney will have 5ft vertical then 3.5ft horizontal then 2ft vertical

any insight/experience on a stove like this would be a great help as im pretty new to this as you can probably tell from my terminology

thanks Ben

[joseph]

Why such a small feed chamber and riser?

[hpmer]

A 3.5" burn chamber isn't going to give you much output. I've been amazed at how much better a 6" was vs a 4". Having built larger systems I am now consistently disappointed in smaller stoves, and doubt I'll ever build such a small one again.

So, unless you have space constraints I would strongly suggest you consider something larger. You can always run a larger stove at less than full capacity, but you can't go the other way.

[blrh93]

a 3.5" riser built from 1" thick fire brick will have a diagonal of 7.7", i could increase to 5" riser but the diagonal would be 9.9" in a 10" diameter barrel would this impede any cyclonic effect? maybe i could round off the corners of the fire bricks, although maybe i should find a slightly larger barrel. i only need to heat a 10ft x 20ft room and space is quite a constraint

[joseph]

Nov 12, 2013 16:34:02 GMT -8 blrh93 said:

a 3.5" riser built from 1" thick fire brick will have a diagonal of 7.7", i could increase to 5" riser but the diagonal would be 9.9" in a 10" diameter barrel would this impede any cyclonic effect? maybe i could round off the corners of the fire bricks, although maybe i should find a slightly larger barrel. i only need to heat a 10ft x 20ft room and space is quite a constraint

So 3.5 + 1 + 1 gives 5.5 on the outside of the bricks with 7.7 inch outside diagonal, and you want to fit it in a 10 inch barrel.  That does not leave room to insulate the riser.

Is it actually 1.25 inch firebrick? Or is it something like vermiculite board, which is already insulated?

[satamax]

3.5x3.5 = 12.25"² minus let say 30% because of the friction in the corners, =8.575"²

5x5xpi /4 =19.63"² not the same at all.

[blrh93]

ok so a 5" circular riser is going to be over twice the effective area of a 3.5" square? maybe 5" flue + 8" flue filled with vermiculite in between would be better? i do have a spare length of 5" twin wall insulated flue would this make an adequate riser?

would you advise to continue through with a circular burn tube and feed tube, how would you insulate these?

[hpmer]

Yeah, if it were me, I'd scrap the brick idea and do a castable refractory. Your double pipe idea is better but the inner pipe will burn out quickly so the insulation should be mixed with clay slip and will quickly become the inner of the heat riser.

I use a clay:ash mix but your vermiculite might be even better than ash.

A 10" interior of your outer barrel would allow for a 6" round heat riser with 2" of insulation. That allows for a 5" square feed chamber which will be much easier to load, clean, etc.

[hpmer]

Wait a minute. 10" - 6" - 2" - 2" = no room for the gases (it's been a long day), but I do think you'd be happier with a bigger barrel and larger inner workings.