rough but it works

Hi
Here is a picture of my J-tube construction,
Then I edited it to show the , secondary air tube position, just to give a rough Idea whet the air tube is located.


The left side has the holes, that are located in the riser portion.

Question to the stove builders, what thickness of steel did you use for the firebox and heat exchanger.

Just priced out steel for building my fire box, and almost had a heart attack at the cost.
Over $ 400, Canadian

Looking at alternatives,
Maybe as I seen it sometime ago by I think Rom1nb, using a 20lb propane bottle for the fire box?

At least I know where to get some free propane bottles.

remember this


Well, now instead of building a firebox , I am going to modify anothe 20lb tank for the firebox.
As Rom1nb did.

Picture to come shortly

you can make it out of a gas bottle as ive cut one up and straightened it out

it gave 33" x 12" 3mm steel

you think thats expensive steel here is extortionate at 90.00 for 33" x 33" 5mm ( 1000mm x 1000mm x 5mm )

for thickness of wood burner i prefer to use over 3mm for the firebox area
i have used ss in 2.5mm for firebox area and it has bowed out due to the heat at the front of it now ive used it more and more since the install of it
another build ive used 3mm and its been given away once finished as its all scrap anyway
on another note any steel is better protected by a coating or firebrick


rom did use a gas bottle firebox

https://woodstoves.forumotion.co.uk/t270-my-first-rocket-stove-space-heater

https://woodstoves.forumotion.co.uk/t204-new-rocket-stove

Thanks gadily,
I now have collected another 2 bottles ( 20 lb )

So I am sure I can make something work with those.
with a firebrick mod to the inside.
Also thanks for the links
Cheers:

If you are going to use a gas bottle for the firebox I would suggest using the refractory recipe that ppotty1 used.

You can line the walls with it, that steel bottle will not hold up over time.

That`s a damn good Idea
Thanks Trying2Hard

Need help figuring what I need :

My scenario is, I have a a low slope roof on my Garage,
6" outlet from my RS, what do I need to basically put the exhaust through the low slope roof.
without burning down the garage.

FYI:,
took RS apart to redesign the secondary air inlet,
and build the new the front burn box.

CHeers all

Also , what Canadian suppliers.

i have the same problem myself

however with the garage i have it has an apex roof so im putting it at that point there

i also have box section profile sloped roof and thats given me a headache

heat problem if using 6" then id use 7" and insulate in between them



the top one is a payed for one

the bottom one is using another piece of steel to create a space between the roof and the flue pipe however needs a deflector plate to deflect rainwater

I have box profile steel roof cladding at work, fixed onto a timber (tongue & groove on beams) roof structure. I have a 5" flue going through, near the apex but just a foot or so down on the rear slope (the roof is double pitched, shallow angled).

What I did (nearly 30 years ago) was cut an 8" diameter hole in the planking - from inside. Then cut a slightly smaller hole in the roof cladding, concentric with the timber hole of course. Make (by rolling) or buy an 8" diameter short piece of steel pipe which goes snugly through the hole (carefully nibble the steel cladding so the pipe is as snug a fit as possible). This pipe acts as a sleeve, for protective purposes. It can protrude through the hole to the outside a few inches and is better to do so. By prior welding fabrication, have 3 or 4 small tabs fixed to the outer rim of the end protruding through the inside in such a way as to use them to screw through and fix the whole sleeve to the roof. Screw through into the timber, from within. The sleeve is now fixed in place. It doesn't need to be heavy-duty stuff - 3mm wall pipe or rolled 3mm plate is plenty.

Go outside and onto the roof and seal against rainwater around the protruding sleeve pipe - hence a few inches protruding helps with this. This sleeve shouldn't get hot enough to be any problem for lead flashing or even tar-based roof sealant or roof-felt.

Through this sleeve is centred a 5" mild steel flue pipe - from a conventional wood-burner. and also acting as the flue for a hood positioned about 2 feet over a small coal forge. The flue pipe protrudes through the sleeve quite a bit more - about a metre. Slipped over the outside of that is a 2nd upper sleeve, which happens to be a piece of stainless steel duct pipe that I scavenged. It's about 9" diameter and so just larger than the 8" lower sleeve.

This outer pipe is about an inch longer than the flue pipe proper and is then 'hatted' with a wind-proof cap-piece. Its very light and just sits lightly on the roof cladding, just over the sleeve piece, cut to the basic pitch angle. By virtue of sitting over about a metre of flue, it can't fall off or go anywhere. It's roughly centred by some little pieces of s/s on the inside near the top that are bent by hand when fitting to just centre this outer piece. I've also lead flashed around the rain-ward edge of this too. This 2nd upper sleeve is mainly to provide additional weather protection (it cover the lower sleeve and flue exit) and as insulation value around the steel flue.

If no 2nd upper sleeve is used or available, then a rain deflector can also be welded around the proper flue pipe at a point just above the exit from the sleeve. This will either have to be done first and then the flue inserted carefully from above (on the roof) or the flue set up and the deflector added later (welding on the roof). Careful close tolerance fabrication could permit tight fitting and the use of high temp silicone.

gadily wrote:

you can make it out of a gas bottle as ive cut one up and straightened it out

it gave 33" x 12" 3mm steel

you think thats expensive steel here is extortionate at 90.00 for 33" x 33" 5mm ( 1000mm x 1000mm x 5mm )

for thickness of wood burner i prefer to use over 3mm for the firebox area
i have used ss in 2.5mm for firebox area and it has bowed out due to the heat at the front of it now ive used it more and more since the install of it
another build ive used 3mm and its been given away once finished as its all scrap anyway
on another note any steel is better protected by a coating or firebrick

Are you in England Gadily?

If so, that is indeed an extortionate price for such a piece of steel plate. For a 1 metre square piece of 5mm plate, you should be paying about half of that - ie, about £50 max. Hunting around reclamation and scrapyards should make that less again - even half that again.

Here's someone I use a lot and who are national with many depots and a full delivery service (though you can self-collect too). Go down the side menu to Steel and have a look through. Web prices are quotable and they will stick to them. If they haven't got in stock at the nearest depot, they will usually have it at one of the others and get it for you in a few days. As regards the Lancs depot (Haydock), they have absolutely oodles of stuff in stock at all times and there's usually any steel you want.

http://www.fhbrundle.co.uk/

A metre squared is just over 39" x 39" btw (not 33 x 33) and for standard 2m x 1m plates you will tend to find they are usually about 1010 - 1015mm in the width. So you can say more or less 40 inches.


As regards fireboxes and the gauge of steel plate, I would always consider 3mm to be an absolute minimum (for any longevity) and the use of low-pressure gas cylinders mirrors this gauge. Even 3mm will bow with heat (and bow easily), as will thicker steel in some cases (as does cast iron eventually in burners and in coal fire pieces - and as also most definitely will stainless steel).

For burners I've made in the past I've considered 5 -6mm plate as the standard material, fully welded all round. The use of 10mm is even better, especially the top plate. Obviously there's a cost and weight factor as the steel thickness rises, but it pays back over time quite easily. The use of gas cylinders as wood-burners is ok, but at the end of the day - they're only about 3mm thick. For simplicity and the ease of acquisition and for a few years service, they're fine enough.

I've used 10mm plate for quite a few burners (firebox and tops) and they are virtually unscathed over years. I've used 10mm plate for a sunken fire pit in the forge and ditto. I replaced a 6mm cast iron throat plate in a domestic coal-fired room-heater (the cast bowed like a banana over 20 years and then cracked) with 10mm steel plate, cut and notched and tabbed to replicate the original shape, and so far (2 years) it's still quite flat and undamaged otherwise.


As regards using stainless steel for anything (burn tube or firebox or exchanger), then it's likely that due to availability (and so cost) but also the difficulty in working with s/s (especially thick stuff), that any such usage will be with the thinner sheet. Typically say 1mm (or even 0.8mm) for thin ducting and pipe up to say 2mm for exhaust pipe (?) and maybe 3mm maximum. Few people I imagine will be rushing out buying (or finding) 5 and 6mm stainless pipe/plate.

As good as stainless steel is for resisting higher heat (per mm, per molecule, per mass) than plain or mild steel, it's not to say it will necessarily be unchanged by high (and repeated) heat applications. This to a fair degree depends on the grade used. It will also depend upon any welded areas, how they were welded and with what material. In addition, stainless is an extremely poor (by comparison) heat conductor. It's so bad that it's a welder's nightmare (especially thin sheet) because of rapid (almost instant) and extreme distortion. Because the intense heat of a weld is quite poorly dissipated from the weld zone, there is the situation of an extreme heat and relatively cold zone about the weld. This promotes mass distortion. You can almost see a piece of sheet go travelling across the bench after a tack at one end. The way to combat it is mass clamping, small as possible tack welds, plenty of them and careful sequential welding.

What then happens when you build heat chambers (like fireboxes) out of stainless is the likelihood of mass distortion, bowing, twisting, etc. Obviously it can be done and if done carefully (and heavily) then can be extremely good - but it's also extremely difficult and no doubt very costly. Personally I wouldn't use stainless steel sheet for any component of a burner, from the point of view of distortion alone.

Paul Lancs wrote:

Are you in England Gadily?

If so, that is indeed an extortionate price for such a piece of steel plate. For a 1 metre square piece of 5mm plate, you should be paying about half of that - ie, about £50 max. Hunting around reclamation and scrapyards should make that less again - even half that again.

yes its lancaster and winter prices as i have a few stokists here

plenty of scrap yards been to loads of them those with cameras you buy by the ton and not allowed to enter the yard anymore due to ffin h&s

i have bought scrap before and its the grinding the paint and rust off as its time consuming to do as ive done it with a grinder and sent the neighbours nuts with it

the last lot i paid 200.00 for off cuts in total sizes below

3mm 1515x1250
3mm 2400x1000
3mm 1525x895

5mm 1160x1160 and some extra pieces

then hire van and fuel on top

easy peasy

Thanks Guys