Navitron Renewable Energy and Sustainability Forum

BIOMASS => General => Topic started by: Greenbeast on October 17, 2012, 08:26:29 AM



Title: DIY wood burner with boiler???
Post by: Greenbeast on October 17, 2012, 08:26:29 AM
I'm a trainee bodgineer and i'm refurbing a static caravan on the cheap.
Looking to build my own wood burning stove, and if possible include a water jacket

What thoughts come to mind on possible designs and problems i might have?

Initially thinking of using an old gas cylinder (i built my first forge from one) but then a making a steel plate box from scratch might be more sensible


Title: Re: DIY wood burner with boiler???
Post by: biff on October 17, 2012, 09:17:05 AM
Good morning Greenbeast,
                         It might be better to buy a second hand stove,something with a proven track record for efficency and safety.There are loads of different type stoves for sale,You could hardly buy the material to makeup a stove for the price you would pay for a decent secondhand one.The safety factor is the all important one and you will need,smoke alarms and fire extinguisher at each end of the static,
  This would be the one of the most important decisions,in your circumstances which needs serious consideration.
                                                                 Biff
                                                                                     


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 17, 2012, 09:36:22 AM
Yes you could be right


Title: Re: DIY wood burner with boiler???
Post by: billi on October 17, 2012, 10:02:29 AM
Perhaps an"ordinary" stove and a  selfbuilt heatexchanger for the flue pipe ???



Title: Re: DIY wood burner with boiler???
Post by: danny stardust on October 17, 2012, 04:06:38 PM
I considered incorporating a back boiler or flue heat exchanger in my log burner in the static.
But as there was only me and it being a temporary stay in the static while my house was getting certain renovation work I decided against it in the end. The van was often left unheated and uninhabited for long periods too, and any system could suffer frost damage unless it was drained down.
Also the generally lightweight structure of a caravan is not ideal for supporting a large tank. In the end for simplicity I just kept a huge pan on the stove's top surface that could be decanted for the dishes and washing when required. It also made a reasonable heat battery during the night when I let the stove go out over night for safety reasons.
It might be a fine balancing act trying to heat the large tank of water and not have the place roasting from the radiated heat of the stove.
I could heat my static from 0deg to a balmy 28deg C in just a couple of hours with stove cranked up to 11..........while the beers were chilling in the snow outside.
It is possible to cook on a stove too, so possibly choose or make one that has a decent sized flat top area. My stove had a large top surface of 13" x 25". I recall having an abundance of pans on the go once, think it was frying pan with chops, tatties boiling, cauliflower simmering,  with spinach steaming above, home made cheese sauce on the go, and a quick gravy pan squeezed on at the end (no lumps in cheese sauce or gravy by the way). It did get a tad hectic at moments, but made club DJ Carl Cox working 4 decks looks simple! LOL

But as mentioned already, fire extinguishers and at least a couple of working smoke detectors are an absolute must to have in place.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 17, 2012, 07:30:39 PM
i'll likely be living there full time for 2-3 years

it'll have full kitchen and shower room and plumbing for both,


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on October 21, 2012, 09:52:41 PM
Hi we have lived in a static for 6 years and I built a sedora type stove. Google it. Best thing since sliced bread.
Cost me next to nothing and does stay in for long periods. The best bit it will burn almost any thing including sawdust and shavings.
We don't have a boiler but the web sight shows one can be fitted
PS don't build it the same size as the 3000 or you will fry, scale it down in width not height.

Best of luck statics ain't as bad as people make out it just a different life style.

Paul


Title: Re: DIY wood burner with boiler???
Post by: dhaslam on October 21, 2012, 11:19:12 PM
The Sedore looks like a good design.    It needs secondary air  at the  flue outlet which would also help water  heating  coils in the  back section.   The only thing is that the tall chimney  might be a bit difficult for a caravan.   


Title: Re: DIY wood burner with boiler???
Post by: knighty on October 22, 2012, 01:44:22 AM
(http://www.sedorestovewest.com/uploads/7/5/8/7/7587287/9852359.jpg?323)


it does look quite good

but should have access to the back of it, for cleaning etc.. ?
(especially if it has a water heat exchanger in there)


EDIT: actually...

it's advertised that you can fill it to the brim, and then leave it going slow for 24 hours....  but it doesn't look to me like the wood will flow into the burn area on the right very well and/or it'll fill up with ash before that ?


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 22, 2012, 07:48:48 AM
Hi we have lived in a static for 6 years and I built a sedora type stove. Google it. Best thing since sliced bread.

Best of luck statics ain't as bad as people make out it just a different life style.

Paul

Thanks i'll check it out.

TBH i'm really looking forward to it, currently sharing a house with my ex-wife and the static is on a farm in the country where my forge/workshop is, can't wait!


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 22, 2012, 08:48:48 AM
looks interesting, any further tips on building one?

Did you use corrugated steel? anything you changed about the design?


Title: Re: DIY wood burner with boiler???
Post by: spaces on October 22, 2012, 02:23:03 PM
Greenbeast, google "Aprovecho woodburner" - there are a couple of pdfs which are full of great info. I'll be building a rocket stove flued through an old 45 gallon drum later this year to heat a (well-insulated) garden shed, hoping to use just a bundle of sticks of kindling a day for heat to keep stored items dry. You'd ideally need a header tank connected to the mains for heating water off an uncontrolled heat source, not easy in a static. How about a cast iron bath outside, with a fire lit under it, it doesn't need be as crude as it sounds - it could all be boxed in and have a chimney away from and above the occupant, with remote controls for the air supply from within the bath! With a bit of pipe, a pump/gravity and a well-insulated cover this could also be your hot water storage and supply. Even build a small shed round it all!!  exhappy:
 


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 22, 2012, 02:26:58 PM
i will check that out thanks.

ha ha, nice idea, i think i'm still looking to keep things a little more civilised  ;D

hoping i can pressurise the coil as per: http://www.navitron.org.uk/forum/index.php/topic,18459.0.html (http://www.navitron.org.uk/forum/index.php/topic,18459.0.html)


Title: Re: DIY wood burner with boiler???
Post by: spaces on October 22, 2012, 02:43:55 PM
More civilised to have a sauna shed with hot bath than tiddling about in a caravan shower, in my book.  8)


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 22, 2012, 03:27:06 PM
i'm installing a full shower room with a decent sized shower cubicle  ;D


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on October 22, 2012, 09:06:11 PM
Hi made my stove out off 2mm steel folded still going strong after 5 winters. It burns so well that I only clean the ash weekly.

My chimney is only 4 in double wall above the caravan, about 2m in height, with 1.6mm stainless welding wire for guilds. Single 4in inside.

Yes they will stay in for 24 hours sometimes mostly about 16hours.

I have one in the caravan and one in the workshop would not swap for any thing. Will try and post a picture.

Paul


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 23, 2012, 08:04:58 AM
Excellent thanks for that, a pic and some dimensions would be great


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on October 23, 2012, 02:13:06 PM
(http://)
(http://s9.postimage.org/6y4pufxyz/IMGP0044.jpg) (http://postimage.org/image/6y4pufxyz/)

Here a picture of the the one in the caravan not very pretty but was built from scrapes in a day. Keeps the place nice and warm.

Its about 30in high 16in deep and 12in wide.

hope that's some help.

Paul


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 23, 2012, 02:16:43 PM
great, that helps thanks, do you think flat sheet steel would do?


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on October 23, 2012, 02:24:22 PM
Hi I would have thought so, it's just that I've got a folder and had some 2mm steel to spare. Made the rest out of 6mm steel, IE the back chamber lid and base.

Paul


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 23, 2012, 03:01:41 PM
thanks for your help :)


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on October 23, 2012, 10:21:51 PM
Alfie the dog like it


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 23, 2012, 10:27:24 PM
i might get some drawings made up and have the steel cut for me, then i can weld it up during my welding evening course to save time ;D


Title: Re: DIY wood burner with boiler???
Post by: dhaslam on October 23, 2012, 11:51:36 PM
Are the two  stoves identical and  does the one in the workshop  have  a taller chimney?  If so  is there any difference in performance?    Although quite simple  it is  quite a sophisticated  downdraught  design.  Using a water heating coil  in the rear  section  might reduce the draught slightly so the chimney would probably need to be a little taller to compensate.   

The draw is very impressive in the video below, no smoke to the room with the  door wide open  but that is with the chimney already warm.   
   
http://www.youtube.com/watch?v=rb83h6kts7o       


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 07:51:08 AM
is the back are the best placement for a coil/boiler?

How should i create that, should i buy a standard 'clip-in' boiler and integrate it?


Title: Re: DIY wood burner with boiler???
Post by: desperate on October 24, 2012, 08:49:21 AM
I think the best position would be as high as possible well above the combustion zone, then you can keep the combustion as hot and efficient as possible, and extract the heat from the clean gasses before they exit the stove. Look at the design of all gas boilers, they are all the same, there is no flame impingement on cold surfaces by design and all good woodburners should be the same.

I have a woodwarm with a back boiler, it is obvious that the boiler is in the wrong place there is almost no combustion at the bottom of the boiler and it gradually gets covered by ash, and also it is in the zone where the wood is being pyrolysed to release the vapours and gasses, putting a huge bucket of cold water in that zone is bound to condense those vapours back into liquids and tars that condense all over the boiler.

If I had the time I would build a stove using a cast iron gas boiler heat exchanger mounted at the top of a firebrick lined combustion chamber, I keep looking at our stove and thinking it is possible to do something similar, and to that end I have squirreled away two big heat exchangers. But if you feel you could use them, they are yours. I could post a piccy or two if you are interested.

Desp



Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 09:03:54 AM
a pic would be great desp, thanks

And thanks for your thoughts


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 09:11:14 AM
frustratingly i have an old cast iron gas back boiler in my lounge (actually as you well know!) but as we are now selling the house i can't start ripping apart the fireplace to extract it.


Title: Re: DIY wood burner with boiler???
Post by: desperate on October 24, 2012, 09:11:35 AM
No worries mate, dont fancy making 2 of these  in your forge perchance??

I will post a piccy this evening, I have to go to work soon.

Desp


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 09:14:21 AM
two whole stoves with boilers?

Yeah, don't see why not. not sure when i'm gonna actually get time to do it but if i'm doing one, an extra should be no trouble


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 10:04:08 AM
how do boilers integrate with the back plate of the stove?
trying to get my head round how to  design and put together these things


Title: Re: DIY wood burner with boiler???
Post by: dhaslam on October 24, 2012, 10:47:00 AM
There doesn't seem to be any illustrations of the coils normally used but they are made from stainless steel and  quite expensive.   Roughly there needs to be about one square foot of boiler surface  for each kW  of output  but that depends on the temperature.    Running in the cooler flue area might need a bit more.    I would be inclined  to experiment with 10mm copper  and connect to a small open tank with gravity feed.     Copper that size is inexpensive so you could add more  until the maximum output is reached.  Commercial stoves are probably still designed that way.   The flue temperature is  probably going to be in the low 100sC so the coils should be OK  just suspended in the  space.  The coils  would need to be cleaned  periodically so they need to be accessible.     

I wonder how important the corrigated sides are to the  design, something to do with air circulation perhaps?   It might be possible  to simulate the effect with a few baffles.   


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 11:21:54 AM
Thanks, for that mate.

yes regarding the corrugations, i could replicate something with baffles but my inclination would be to go for the simplest design possible first.

Using copper certainly would make it easier than stainless steel.
I'm intrigued to see what these boiler's of desperate's are like (having never seen one) and how easy they would be to integrate.

I searched just now on add-in boilers and got results for stainless steel boxes for aarrow stoves. Seems less efficient than using pipework but then i guess perhaps they are taking enough energy out of the fire with the surface area of the steel box and not needing the extra area provided by pipes


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 12:01:16 PM
actually thinking about it, the advice to use large bore pipework to aid gravity circuit kinda agrees with using a box as the boiler rather than some kind of  pipe coil doesn't it?


Title: Re: DIY wood burner with boiler???
Post by: dhaslam on October 24, 2012, 12:28:54 PM
The difference between 10mm and  28mm pipe  is  about 8:1 so if  an 8 kW boiler  uses  28mm pipe it is   much the same thing as a  1 kW  boiler using 10mm.   The big difference with 10mm is that the  surface area is much greater for a given volume of water so it should heat it more efficiently.    If  it looks like the  stove can produce more heat to water without cooling  the flue too much  you could add an extra coil or two and combine them to larger pipe  for circulation.    Because you need to have a small sized stove, due to the small space,  the output to water is going to be limited.   

The reason that pipe is used for the heat exchanger  is because  the heat is exchanged in the flue rather than  in the firebox.  The plus side is that the fire burns a lot  better but the transfer of heat is at much lower temperatures and needs to be more efficient.   This means having more surface area to water volume.     


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 01:36:35 PM
Thanks for that!

Although built in and add-in boilers seem to be boxes, why not pipes if that's best?


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on October 24, 2012, 02:04:25 PM
Hi if you look on www. sharron_reive.tripod.com/catalogue.html you will see the heating tubes for the fire.

Paul


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 02:41:35 PM
additionally, i wonder if it's feasible to take air in from outside?


Title: Re: DIY wood burner with boiler???
Post by: Heinz on October 24, 2012, 03:12:51 PM
how do boilers integrate with the back plate of the stove?
trying to get my head round how to  design and put together these things

Found a photo looking down into the Sedore stove which shows a zig zag pipe on the back of the firebox, thought I'd saved it, but it appears not... Had a quick google for it and can't find it. Anyway, the 'coil' was on the back of the box the wood goes in. Pretty simple/crude thing with only about six horizontal bits plus the bends. Didn't seem to go all the way down, perhaps to avoid the coil being fixed to the replaceable section at the bottom of the divider?
I'm quite taken with the Sedore design and have been sketching some ideas. Wondered about putting a flat tank in instead of a divider. Should heat water and avoid the bottom of the divider burning out?

H


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 03:27:33 PM
Ok how about this, from our talks here i've tried to assimilate the features i should include

So it's got an additional air intake (secondary), and both intakes are from the rear so that i can pipe them from outside
The copper coil is in the flue outlet area (imagine it winding itself over and back across the wall of the stove), i don't know if this is what you guys intended, i'm happy to change that

(http://i22.photobucket.com/albums/b316/GreenBeast999/woodstove_zps3d8276b0.jpg)



edit: heinz - i was writing my reply and you've posted yours in the interim, possibly a good idea with the tank instead of divider, other, smarter people will have to comment


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 03:38:54 PM
i like the idea of a window, perhaps i'll orientate the stove sideways to have a nice big window


Title: Re: DIY wood burner with boiler???
Post by: rogeriko on October 24, 2012, 04:16:08 PM
My stove from Koty in Bulgaria is about 60cm cube on the inside, a huge firebox, it came just as a woodstove but I wanted to heat water so I made a flat box about 40cm x 40cm and about 5cm thick out of 4mm steel. I welded up all the edges and put two 3/4" pipes sticking out one side. I installed this FLAT just under the top mounted chimney so all the hot gasses have to wrap around the water filled box on their way up and out the chimney. I have a pumped circuit so it dosnt matter that the two pipes entering and leaving are at the same height. It works great.


Title: Re: DIY wood burner with boiler???
Post by: knighty on October 24, 2012, 04:21:56 PM
I'd put a bend on the end of the secondary air intake so it pointed up, and maybe mount it a bit higher - the updraught should help draw air in through it and it will (hopefully) stop it feeding air directly into the fire ?

(I have no experience with these, just guessing)


I'd also be tempted to put your heat exchanger at an angle, so the hot gasses have to pass through it

or, instead of mounting it at the back, mount it at the top (away from the flames) ?:


EDIT:
or get a couple heat exchangers like THESE (http://www.ebay.co.uk/itm/Baxi-Bermuda-45-3M-For-Back-Boiler-/200834886912?pt=UK_Home_Garden_Hearing_Cooling_Air&hash=item2ec2b12d00)
(top of the 1st photo)


Title: Re: DIY wood burner with boiler???
Post by: dhaslam on October 24, 2012, 04:25:46 PM
I think that the  addition of secondary air at the  gap  under the  divider will produce some flame into the  rear chamber and it may sometimes do that anyway with the original air supply from the front.     By having  a flame  at the bottom of the rear compartment  it should  have  plenty of heat to transfer to water.     The secondary air in my stove  (Walltherm) goes  under the grate where the flame burns  downward.  It should be possible  to obtain a similar effect.   It would be nice to have a small observation window  at the rear to see what is happening.   The Walltherm  is different in that the rear is all narrow channels  surrounded by water  and  initially it is so cold that the fire won't burn downwards and the  smoke has to be diverted directly to the chimney. It takes about  15 minutes for the chimney to be hot enough to draw and   even then the  downdraught  is weak until the water  in the channels reaches 60C.     Having the open flue with  just some pipes gets around this problem.    The Walltherm stove is supposed to be 93%  efficient  and this one  could well be heading that  way.  

Note that having an external air supply for the stove  means that  there is less through ventilation so  CO alarms  etc are more important.  


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 04:38:44 PM
dhaslam, so do you think the secondary air intake is correctly placed/orientated?

i could put a window in the rear chamber also

any thoughts on Heinz's idea of making the baffle itself into a boiler tank?
perhaps 20-30mm deep, obviously taking up a large portion of the stove area


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on October 24, 2012, 05:32:09 PM
Hi you don't need the secondary air it works fine as is.

I have a peep hole on the one in the workshop so i can see what goes on in the rear chamber, tomorrow i will light it and try to take a photo to show you what I mean

The external air should work because they make one for the stove.

Did you See the link to the boiler tubes?

Paul


Title: Re: DIY wood burner with boiler???
Post by: desperate on October 24, 2012, 06:00:45 PM
Blimey, this threads moving on a pace, what have you started Mr GB


the image above in the foreground shows a potterton 24kW exchanger it is about 40-50kg in weight, and to the rear an Ideal (Ithink) about 20kw weighing around 25-30kg. As you can see they are both heavily finned to present a large surface area to the gasses and both of them are basically a pair of headers connected by paralleled runners. This piccy shows the top of the exchangers or the side facing the flue.

the next pic shows the bottom of the potty exchanger where the hot gasses enter it.

and the bottom pic shows the ideal exchanger, I have forgotten which way round it goes though.

For some reason postimage is messing around with bad gateways whatever that is so I'll attach them instead, appologies if they are in the wrong order facepalm.

Desp


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 06:33:10 PM
lincs, but i wonder if the introduction of secondary air near the flue chamber will, as dhaslam posits, cause flame in that area perhaps heating the boiler better, without taking too much heat from the main chamber.
Yes i did see the coils on the link you posted.

Desp, those are might heavy beasts!
I'm still unsure whether cast iron heat exchanger or 10mm copper coil is the way to go yet


Title: Re: DIY wood burner with boiler???
Post by: desperate on October 24, 2012, 06:35:32 PM
Here's a really quick and dirty sketch of how I figured it could fit into a stove like our woodwarm.
I was thinking of junking the baffle plate and making an inverted funnel to bolt on the top of the exchanger and fit to the underside of the flue spigot. In our stove the whole lot would be just above the top of the door aperture so almost out of sight. It would need an access door to clean the flue but that's a standard bit available off the shelf.

Most wood burner boilers that I have seen are more crude than stonehenge, a bit of gas boiler technology would go a long way to improving the efficiency. The principle is the same, get the combustion over and done with and then extract the heat, I reckon the key is to control the air properly, first it need a small amount of air introduced below the grate to get the wood gassifying then introduce more air via the standard airwash down the front glass. Finally a surplus of preheated air needs to be introduced before the heat exchanger at the top of the flaming zone to ensure complete combustion. These 3 air supplies need to be separately controlled so that the wood is gassified at a rate that ensures it can all be burned by the secondary and tertiary air.

If you're up for it Mr GB you can have those exchangers and some help with design, welding, etc, I did start a thread on this some time back, "A wood powered gasser", but I ran out of enthusiasm really, but I would like to do something again. This piccy is a potty profile that I started converting to a gaswood hybrid wackoold, the plan was to fit a small grate at the bottom of the case and a couple of crude butterfly type valves to control the air. Then whack a couple of metres of spare flue liner on the top to provide a draught and see what happened, sadly as I say I got rid of it. surrender:

Desp


Title: Re: DIY wood burner with boiler???
Post by: desperate on October 24, 2012, 06:40:50 PM
Don't bother with 10mm copper unless you want to make a steam cleaner. You could do it but if you work out how much water you need to shift the heat you will either need a massive pump, or build a matrix of lots of 10mm runners between 2 headers which involves lots of joints sh*tfan:

Desp


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 24, 2012, 07:18:38 PM
thanks for that mate.

I'm still pondering, perhaps we could mount the heat exchangers you have under the flue like you suggest, between the baffle and back wall of the sedora


Title: Re: DIY wood burner with boiler???
Post by: Heinz on October 24, 2012, 07:51:28 PM
Found the pic of the water heating coil, video not a photo which will be why I hadn't saved it....  ::)
http://www.youtube.com/watch?v=z5Ndp9tVIOU

I think secondary air in the smoke chamber is a mistake as that will reduce the 'suck' drawing the gasses from the firebox under the divider and into the smoke chamber.
My thought is to build it simple first and see what happens. Plan is to make a 45gallon drum one for the workshop and mess about + learn with that before starting on the much needed new house stove. Winter approaches  freeeze

H


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on October 24, 2012, 10:41:16 PM
Yes keep it simple, some one as done the ground work and as a patent on the design, mine been keeping me warm for years as is!

Don't fix what's not broken


Title: Re: DIY wood burner with boiler???
Post by: dhaslam on October 25, 2012, 12:00:25 AM
Yes I think the secondary air is important because it  will help burn any  inflamable  gases  remaining that otherwise would go up the chimney.    I would place the inlet  across the back of the  baffle plate at the bottom.   The video suggests that it should extend into the firebox but I don't  think that  is correct because there should already be  sufficient air where the fire is actually burning.      There may be features  in the design  that does lead to a complete burn  but  as you can see with my stove, that has a fairly similar  firebox and air inlet,    that there is a lot of  unburned gas after exiting the  firebox.   


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 08:27:00 AM
ok, couple of modifications, what do you reckon now:

(http://i22.photobucket.com/albums/b316/GreenBeast999/Projects/woodstove11.jpg)


Title: Re: DIY wood burner with boiler???
Post by: Heinz on October 25, 2012, 08:54:03 AM
Not sure how well your heat exchanger is going to do up there, looks kind of cool..
(http://sedorestoves.com/ir0026.jpg)

H


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 09:02:36 AM
Thanks for that image, hopefully the secondary air might change that, to allow combustion of remaining gasses in the second chamber.

Ideally i'd like to get the design right first time, but that might not happen.
Luckily i've got a thermocouple good for 1300C, so i can manually test the heat in different locations if i put some holes in specific places.


Title: Re: DIY wood burner with boiler???
Post by: desperate on October 25, 2012, 09:14:02 AM
Cool image that Heinz, but going back to gas technology again, heat and temperature are different things. A gas flame is way up at 1500C iirc, but the heat exchangers are always way above the flame, but still manage to extract the heat. If the fire box were firebrick lined you could retain the heat, or as much as you wanted until the gasses reached the exchanger. Maybe?

Whaddya think?

Desp


Title: Re: DIY wood burner with boiler???
Post by: Heinz on October 25, 2012, 09:23:15 AM
Just sitting here doodling ideas and had sketched some firebricks set in the barrel/box to create the corrugated inside of the firebox while insulating the firebox and avoiding the hassle of folding the sides. Probably better to cut them into triangles rather than just placing them as diamonds, but should work and avoid the sides burning out. Noticed the Sedore has double skinned bits welded in on the sides of the firebox so burning out is obviously a problem.

H


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 09:45:51 AM
I have a bag of castable refractory here, i could pour my lining  ;D


Title: Re: DIY wood burner with boiler???
Post by: desperate on October 25, 2012, 09:48:44 AM
Maybe a prototype could use thermalite blocks, they are cheap and easy to cut and would last long enough to try the principle. I made a garden incinerator out of them a while back it worked a treat and even melted the inside of the blocks, but they held together for quite a while.

Desp


Title: Re: DIY wood burner with boiler???
Post by: desperate on October 25, 2012, 09:50:24 AM
I can feel a fur-nace coming on svengo
Desp


Title: Re: DIY wood burner with boiler???
Post by: Heinz on October 25, 2012, 09:51:12 AM
Go for it  ;D  What does it cost these days? Last time I used it was about quarter of a century ago (metal melting furnace) and IIRC it wasn't cheap.

H


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 10:03:27 AM
can't remember what i paid, i only ordered it because the min order value for my forge lining bricks wasn't high enough

Thought about using it for the next forge rebuild (imminent) but to be honest i still have loads of fibre blanket


Title: Re: DIY wood burner with boiler???
Post by: desperate on October 25, 2012, 10:11:09 AM
Hmmm .........wonder if you could run a heating system on molten aluminium?? may have to change the stat ralph:

Desp


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 10:14:12 AM
lol, we don't need to concentrate/store the heat in refractory really, but it will protect the metal box

what do you reckon desp?


Title: Re: DIY wood burner with boiler???
Post by: dhaslam on October 25, 2012, 10:26:15 AM
I think that the  secondary air  just needs a pipe with small holes across the back  of the  baffle plate, it could come from the side and  preferably have a way to adjust  the amount of air.

It is a good idea to have some  heat  retaining  surfaces in the firebox to increase the initial  combustion temperature and direct more heat to water.           


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 10:29:07 AM
Ok cool, i did think of that but it wasn't so easily drawn in my 2d paint sketch  ;D

I'm probably going to have mine positioned 'side on' anyway, so i can have the water and air intakes on the 'left' against the wall, with two windows on the 'right' facing the room


Title: Re: DIY wood burner with boiler???
Post by: desperate on October 25, 2012, 10:33:53 AM
Yeah go for it, all gas boilers have insulated combustion chambers to prevent heat loss before the exchanger so why should a wood burner be different, obviously with a stove you want some heat to the room, but I reckon the chances of reducing that too much are very small.

Desp

PS I'd second DHaslams suggestion about a series of small holes.
I would also go for tertiary air nearer the top if it were not too difficult.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 10:39:56 AM
i wonder if its worth making an ash tray that covers the entire bottom surface, that allows you to withdraw it from one side and might make clearing ash easier

edit: i guess if i were to line with refractory this ash pan would posssibly be a sacrificial item made to fit the refractory as close as possible and be replaced if burnt through, easier than replacing walls anyway


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 10:41:34 AM


PS I'd second DHaslams suggestion about a series of small holes.
I would also go for tertiary air nearer the top if it were not too difficult.

top of the fire box i assume?


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on October 25, 2012, 11:04:44 AM

(http://s17.postimage.org/t1s05hhwr/IMGP0045.jpg) (http://postimage.org/image/t1s05hhwr/)

(http://s7.postimage.org/735y55hev/IMGP0046.jpg) (http://postimage.org/image/735y55hev/)

(http://s10.postimage.org/5o3jp4xad/IMGP0051.jpg) (http://postimage.org/image/5o3jp4xad/)

Hi first picture is the workshop stove, second one is the stove just filled with shavings. The stove is running at this point.
The third picture is showing inside the back chamber not very clear but you can see the flames, no secondary air.

The chimney about 2ft up from the fire runs at about 200f when the stove is running nicely.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 11:07:18 AM
The third picture is showing inside the back chamber not very clear but you can see the flames, no secondary air.

The chimney about 2ft up from the fire runs at about 200f when the stove is running nicely.

interesting, thanks for the pics


Title: Re: DIY wood burner with boiler???
Post by: dhaslam on October 25, 2012, 12:00:23 PM

(http://s10.postimage.org/5o3jp4xad/IMGP0051.jpg) (http://postimage.org/image/5o3jp4xad/)

The third picture is showing inside the back chamber not very clear but you can see the flames, no secondary air.


The system is obviously quite good as it is  but it is quite an old  design at this stage.

Would it be possible to  add some air  through a pipe  to test the effect?   It might need glass covering the opening  to eliminate the effect  of air entering and the primary air also might be need to be reduced a little.     It might be possible to  double the  flue temperature or more when there is no cooling.           


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 12:30:49 PM
i'm currently knocking up a 3d sketch or the current layout.
i'll post pics when i'm done


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on October 25, 2012, 01:19:59 PM
The hole is covered up normal with the steel disc. I put the hole there when I made the stove to see what effect secondary air made and as far as I could tell none! With the flue temperature I was trying to indicate that not a lot of heat is loss up the chimney. The fire box was at around 500f.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 02:18:08 PM
here you can see the stove in all it's 3d glory, i've opened up one side to show the internals.
I've not included a refractory/firebrick lining or ash pan for clarity
On some shots you'll have to ignore drawing artifacts (some items leak lines through the flat surfaces)

This is to scale based on Lincs' stove, the heat exchanger is shown as a box covering the flue to save me drawing something more complex.
The two air intakes will go off to valves and then to an outside vent, or just open to the inside of the room

All design elements open to change, please comment!


(http://i22.photobucket.com/albums/b316/GreenBeast999/Projects/woodstove1-1view1.jpg)

(http://i22.photobucket.com/albums/b316/GreenBeast999/Projects/woodstove1-1view2.jpg)

(http://i22.photobucket.com/albums/b316/GreenBeast999/Projects/woodstove1-1view3.jpg)


Title: Re: DIY wood burner with boiler???
Post by: Richard Owen on October 25, 2012, 04:17:17 PM
I am quite taken with the prototyping approach. I might make one as a prototype for my masonry stove.

What's a good mix that would allow me to stick concrete and thermalite blocks together and then knock them down again for modifications?

Thanks.


Title: Re: DIY wood burner with boiler???
Post by: Billy on October 25, 2012, 05:39:23 PM
There must be a reason the sedore has a rather heavy duty back plate "throat".  This must be where the max heat is, it will need to cope with it.  I managed to deform and burn the one on the squirrel before I fitted a boiler.  I reckon the sedore type will suffer more.  What think you?

(http://i1237.photobucket.com/albums/ff479/tutakii/28623605arF.gif)


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 05:50:46 PM
billy, the baffle is currently at 10mm thick, do you think it needs to be more?

shame we can't make it into the boiler itself, would kill two birds with one stone, heat water and prevent such fact breaking down of the steel


Title: Re: DIY wood burner with boiler???
Post by: Heinz on October 25, 2012, 06:24:17 PM
billy, the baffle is currently at 10mm thick, do you think it needs to be more?

shame we can't make it into the boiler itself, would kill two birds with one stone, heat water and prevent such fact breaking down of the steel

Why can't the baffle be the boiler? That's my current plan. IMHO the baffle is the place for the boiler and as my system relies on thermosyphon, a taller boiler should work better than a short one like you've drawn.

You could just move your secondary air tube and make it the lowest part of the baffle. Should give you very hot air and cool the baffle. Win win.

H

H


Title: Re: DIY wood burner with boiler???
Post by: Billy on October 25, 2012, 07:05:47 PM
Was the baffle up to 2" of cast iron on the Sedore?  Hey what do I know, you is the man heatin and beatin.  My grate and fire bars are suffering after burning a bit of coal last year.  I presume it is burning hotter?

I think that incorporating the boiler would be a great idea.  I might be tempted to go for the most exotic material I could afford.  I don't think ordinary mild steel would last long.  My 316 stainless has done five or six years now.  It gets tarred badly in low fire slumber, suffers from massive corrosive juices on the outside, enough to start eating the cast on the chimney collar.

I think the whole idea is great and dribble with anticipation.  My stove is not going to last forever and the idea of burning all that tut just by tipping it in the hopper.   exhappy:

I done gas bottle, charcoal, workshop pipe stoves but this sounds like a tasty idea.

(http://i1237.photobucket.com/albums/ff479/tutakii/28623605arF.gif) 


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 08:17:05 PM
i do like the idea of the baffle being the boiler, just hope it doesn't cool the fire too much, that's the beauty of having the boiler in the second chamber i think.



Title: Re: DIY wood burner with boiler???
Post by: Billy on October 25, 2012, 08:39:22 PM
I mean they have been using wax thermostats for years on engines without any undue problems.  An uncontrolled return temp does cool the fire dramatically.  If the fail safe that bypasses the wax thermostat could be a prv that once open stays open until reset.  The usual prv set to blow in case of really bad things.  It can't be that hard can it?  It just won't meet regs I suppose.

(http://i1237.photobucket.com/albums/ff479/tutakii/28623605arF.gif)


Title: Re: DIY wood burner with boiler???
Post by: knighty on October 25, 2012, 09:14:07 PM
but.... if the baffle is also the boiler.... won't that pull the temperature of the firebox down.... and half the point of the baffle is to keep the firebox temp high ?


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 25, 2012, 09:16:59 PM
yeah this is my concern


Title: Re: DIY wood burner with boiler???
Post by: Heinz on October 25, 2012, 09:20:28 PM
A bit but I can live with it for the sake of simplicity.
When I get around to making it and it doesn't work, you guys can all take the p*ss out of me ...  :hysteria

H


Title: Re: DIY wood burner with boiler???
Post by: Richard Owen on October 25, 2012, 09:43:52 PM
Don't make the baffle, the boiler.

Get the fire going and then take the heat out.

Have a look at gas and oil boilers. If making the baffle, the boiler worked, they would have the flame playing directly on the heat exchanger. But they don't.


Title: Re: DIY wood burner with boiler???
Post by: Billy on October 25, 2012, 10:08:48 PM
Ok, go with that but make sure that baffle is going to cope, you wouldn't bother with a 2" cast plate off a battle tank if you didn't need it.   ;D  Or make it super easy to change if it does go perhaps.  Might be a cheaper option.

(http://i1237.photobucket.com/albums/ff479/tutakii/28623605arF.gif)


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on October 25, 2012, 11:13:31 PM
My stove as 6mm mild steel plate at the bottom of the rear chamber and has lasted 4 seasons and going strong for the fifth.

I'm not trying to be funny but just have ago at making one as it is , only a good days work and 50 quid of steel.

Not a lot to lose for 4 years off warm winters exhappy:


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on October 26, 2012, 07:43:14 AM
yeah i think i'll get the bulk of the stove cut out of 5 or 6mm steel.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on November 05, 2012, 10:40:42 AM
I may experiment knocking one of these up during the christmas break, might use a gas cylinder for a prototype, then when proven order some cut steel to weld up


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on November 05, 2012, 09:59:22 PM
Just go for it and get warm. I'm sat here in my t shirt and it 1deg out side. exhappy:


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on November 06, 2012, 07:29:11 AM
I'd love to tinker sooner than that but a) i have too much work on and b) luckily i'm not actually living there yet, it's just weekends currently


Title: Re: DIY wood burner with boiler???
Post by: Stuart on November 14, 2012, 04:33:45 PM
My Friend is also making a bigger boiler stove. His original full water jacket with baffle sprung a leak. 10 years worth of back end corrosion, cold water straight into back of stove from CH circuit.

the baffle was absolutely spot on.

Stuart


Title: Re: DIY wood burner with boiler???
Post by: knighty on November 14, 2012, 04:45:05 PM
I keep thinking about building one... but I want to heat water more than heat the air...

so I'm thinking it would be best to insulate all around the outside of the burner to keep the heat in.. and then oversize the back boiler to take as much heat as possible ? (but from behind the baffle, not from the firebox)

anyone know what kind of insulation would be suitable?

it wasn't hard to make the home made wood burner we had at work glow red... which according to google is getting on for over 450'C :o


unless it had a air gab around the stove, and then a water jacket all the way around it ?
(pain in the arse to build it tho.....)


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on November 14, 2012, 05:16:03 PM
knighty you could use soft firebricks, that will insulate it very well and shunt all the heat to the back chamber i suspect.

http://shop.vitcas.com/insulating-fire-bricks-24-c.asp
good for 1300C

if it was me i would oversize the steel shell and insulate internally, otherwise the steel will burn away, ask me how i know  facepalm


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on November 25, 2012, 08:29:42 PM
i vented and filled with water a 47kg propane cylinder today.
I'll try to cut it open next week and look at preparing a lid and the baffle

it'll have a 4" flue i think and server as a reasonable prototype before building a decent one, it'll then performs it's duties in my workshop  ;D


Title: Re: DIY wood burner with boiler???
Post by: desperate on November 25, 2012, 08:41:46 PM
Keep it filled with water while you cut it, arrange for the cut to be uppermost, get the wifeys apron and goggles while you wield the angle grinder.

Have fun

speD


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on November 25, 2012, 08:50:38 PM
that's how i did the last one desp  ;)


Title: Re: DIY wood burner with boiler???
Post by: Billy on November 25, 2012, 09:19:20 PM
We always used to weld mini petrol tanks when they were full.

Those were the days eh?


Title: Re: DIY wood burner with boiler???
Post by: Heinz on November 25, 2012, 09:35:56 PM
You mean you didn't use the 'match round the corner' method? Place drained fuel tank behind a wall, reach round with your hand and drop a lighted match in it. WHOOMP !!! and the tank is safe to weld .....  :hysteria 
Used to do this regularly when I was much younger and dumber until one time I was doing a motorcycle tank and it tried to turn itself inside out  sh*tfan:

H


Title: Re: DIY wood burner with boiler???
Post by: Billy on November 25, 2012, 10:18:32 PM
H,

I still have the scars on my face.   ;D

Most of my apprenticeship felt like it was spent cooped up inside a car "fire watching" with a fairyliquid bottle full of water!   wackoold


Title: Re: DIY wood burner with boiler???
Post by: Heinz on November 26, 2012, 12:11:09 AM
Man, I remember that  ;D  Vauxhaul Chevette one side jacked up high, doors open, apprentice doing the 'fire watching' as I gas welded a new sill on. Looked up to see the inside of the car full of flame and a layer of black smoke in the roof of the workshop. Blo0dy apprentice had bug*ered off for his teabreak and not told me.... The boss was NOT happy  :fume
Happy days  ;D

H


Title: Re: DIY wood burner with boiler???
Post by: mike7 on November 26, 2012, 02:31:12 AM
Only just now skimmed through this thread ... epic stuff. Re firebox insulation, for experiments I've used pieces of scrap suspended ceiling panel. Easy to cut, no thermal mass to speak of, and free. Won't last for ever, but it surprised me just how long it survived.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on November 26, 2012, 10:11:21 AM
Can someone talk to me about flues?

What dia, what height?
Double insulated? Does that need to continue above the roof?


Title: Re: DIY wood burner with boiler???
Post by: Heinz on November 26, 2012, 10:20:19 AM
My experience tells me that 4" is too small, 47kg gas bottle stove in the machine shop with 4" flue (it's all I had at the time) is always chucking smoke out the door when filling with wood. 6" is a good size which has worked for me on assorted stoves.
Height, taller is better, more 'suck'.
Double insulated, why? Unless there is something you're trying to protect from the heat, I'd always use uninsulated to get as much heat out of the fuel as possible. Best flue I ever had was some 6" cast iron sewer pipe.
Needs to end above the peak of the roof or you'll suffer from downdraught in certain wind directions.

H


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on November 26, 2012, 10:29:23 AM
Thankyou


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on November 26, 2012, 12:01:09 PM
tips for going through the roof with single skin flue?
don't want my roof burning off.


Title: Re: DIY wood burner with boiler???
Post by: Billy on November 26, 2012, 01:18:56 PM
I welded a 10" pipe through the roof to leave an upstand of about 2".  The flue came through this and left a 1" gap which I filled with fire rope to stop the drafts.  Steel spacers kept it central and the storm collar sheds the water over the upstand.  I also used a flat roof cone under the storm collar and over the upstand.  Belt and braces like.

(http://i1237.photobucket.com/albums/ff479/tutakii/IMG_0001-1.jpg)

I found this is a useful link too.

http://www.stovesonline.co.uk/stove-chimney-documentation/Installing-stoves-on-boats.pdf

I guess you could glue in a pipe.  On the inside where the wood ceiling is I cut circle out and used a strip of ally to make a fire stop ring.  Obviously an uninsulated flue is going to be a bit hotter.  My was fine but I did change to insulated on the outside as I got a cold spot and the clag used to build up too quickly.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on November 26, 2012, 02:04:14 PM
Thanks Billy


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on November 26, 2012, 09:49:33 PM
Hi I've got a 4in pipe on my fire. just a pipe on the inside of the caravan to get the heat, out side there is 2meters off home made insulated flue.

The 4in pipe is old steam pipe from the scrap yard, outside 6in spiral ducting with rock wool between. These fires need a good draw.

On top off the caravan I welded a 6in collar to a plate and bolted it to the roof, then put the 6in spiral ducting over it.

We are in Linc's so the wind is cruel but still standing.

A 19kg cylinder should make a good stove, best of luck.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on November 27, 2012, 11:28:15 AM
yeah i think i might make up some sort of insulating collar for the roof space


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on January 16, 2013, 08:25:14 AM
I've got the body cut down from the cylindeer and cut my lid out (finally had a play with my gas axe, it's bloody brilliant!)

I'm going to make it a bolt down lid so that i can experiment with water jackets/boilers by removing the top.

Hopefully continue working on it this weekend, this cold snap has me energised on the matter again!


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on January 16, 2013, 08:28:36 AM
You can buy hard firebricks in all shapes and can cut them also, i'm wondering whether the baffle could be made out of 20mm firebrick that slides down slots in the walls, that way it''s replaceable but won't burn out :)

Thoughts?


Title: Re: DIY wood burner with boiler???
Post by: dan_c on January 16, 2013, 08:44:52 AM
You can buy hard firebricks in all shapes and can cut them also, i'm wondering whether the baffle could be made out of 20mm firebrick that slides down slots in the walls, that way it''s replaceable but won't burn out :)

Thoughts?

The baffle in my Westfire Two stove is ~25mm "firebrick" and it holds up well. It rests on another firebrick at the back, and rest on a pin each side for support at the front. Overall it probably spans about 450mm at the front.


Title: Re: DIY wood burner with boiler???
Post by: desperate on January 16, 2013, 08:51:21 AM
You can buy hard firebricks in all shapes and can cut them also, i'm wondering whether the baffle could be made out of 20mm firebrick that slides down slots in the walls, that way it''s replaceable but won't burn out :)

Thoughts?

My plan (if I ever get round to it) is to line the casing with thermalite blocks as they are really easy to cut and drill, and then render the inside with fire cement.

spDe



Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on January 16, 2013, 08:54:00 AM
Thanks!

The prototype will be all steel but when i build the real thing i think i will cast the interior in refractory cement, if i am clever enough i can leave a slot down the sides for firebricks to slide down :)

Just read the sedore manual (http://www.sedoreusa.com/pdf/manual.pdf (http://www.sedoreusa.com/pdf/manual.pdf)) and am getting excited about cracking on again.
I'm going to forgo the secondary air to start with (as has been suggested by a couple of people), due to simplicity and also the sedore guys reckon the smoke circulates and burns off in the primary chamber.

edit: desp you got there while i was typing  ;D


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on January 16, 2013, 01:34:09 PM
After reading the sedore manual and more fully understanding the design and operation it occurs to me that it is the width and depth that control fire size (for a given air inlet aperture.

So the best design is probably quite tall as you can load it and leave it, they quote burns times of 12-20 hours, no doubt this could be extended proportionally by making the box proportionally taller.

I'd be inclined, personally, to make the floor area smaller, for my smaller dwelling (as was mooted originally based on lincs' comments) but keep the height (thus changing the height to area ratio)

Make sense?


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on January 16, 2013, 02:09:31 PM
Also i think the corrugations might be relatively important for gasses to circulate, what do you reckon?
It'd be easier to build without them


Title: Re: DIY wood burner with boiler???
Post by: dickster on January 16, 2013, 04:21:20 PM
Two penneth worth.

Built 3 little brick walls round the back and sides of squirrel stove to act as heat store. V good.

Used cement fibre boards where flue went through roof.

Put flue pipes in upside down, enjoyed some high tar inhalation then put them in the right way up.


Title: Re: DIY wood burner with boiler???
Post by: Heinz on January 16, 2013, 11:45:21 PM
Also i think the corrugations might be relatively important for gasses to circulate, what do you reckon?
It'd be easier to build without them

Methinks the corrugations would help with circulation but a similar effect could be had by adding a few bits of flat bar vertically on the inside for less effort than all that bending. It would also depend on the fuel. If you dump in a random heap of logs, no corrugations required. Carefully pile in logs and the corrugations become important?
The other thing is the Sedore manual states,
'As of May 1992, your furnace is approved to burn the following fuels:
Hardwood, Softwood, Woodchips, Sawdust, Wood shavings, Cob corn, Kernel corn,
Sunflower seeds, Sunflower tops, Recycled hardwood cubes, Barley, Oats, Wood pellets,
Recycled cardboard cubes, and Tree saver firewood. '
Now, if you dump in a load of sunflower seeds, the corrugations are doing nothing, so are they really vital or part of the patent, sales pitch, mystique?

H

PS why the feck would anyone burn barley, oats, etc? Is food really worth so little?


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on January 17, 2013, 07:42:24 AM
good points Heinz, i did consider the random vs stacked wood idea. Definitely a good one on the more fluid fuels, because i wasn't planning on using them i didn't even think about them filling all the voids.

I'd like to get my all steel prototype running in the next few weeks if possible. That won't have any corrugations anyway.


Title: Re: DIY wood burner with boiler???
Post by: Brian H on January 17, 2013, 09:00:28 AM
I've come across grain burners before. It seems wrong, but the ex-farm price of grain is often lower than the price of bought in fuel.


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on January 19, 2013, 10:46:47 PM
Hi you burn grain that is mouldy or no use for cattle, very cheap


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on January 27, 2013, 10:10:30 PM
Made some progress this weekend, got my cylinder 'lip' sorted as well as the baffle, added a flood internally, also tidied up the lid and started cutting the hole for the flue (lid not shown)
(http://i22.photobucket.com/albums/b316/GreenBeast999/Projects/2013-01-27145837.jpg)

Next job is cut a opening for loading  and give it a door/lid
Then drill air vents and build a sliding cover :)


Title: Re: DIY wood burner with boiler???
Post by: Heinz on January 27, 2013, 10:31:15 PM
Looking good  ;D
'Flood' ?

H


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on January 28, 2013, 07:35:41 AM
ha ha, floor!

Wanted a flat base to build the fire on and then the opening at the bottom is a little more calculable in terms of area (should i need to)


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on January 28, 2013, 11:53:12 AM
Should work well that.

If your like me you will get it finished just in time for the summer heat wave ;D


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on January 28, 2013, 11:57:56 AM
Yeah it wasn't lost on me that i made the most progress on a day that was brilliant sunshine....


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on January 28, 2013, 11:59:03 AM
I just realised i've got an old copper cylinder in the yard, so i can properly play with boiler/water jacket options :)


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on February 02, 2013, 06:44:03 PM
got some more work done today, lid bolted down, opening cut out, door cut out and fitted, air vent fitted.
Just got to add a flue interface (and flue) and put a port in the back for priming the flue

(http://i22.photobucket.com/albums/b316/GreenBeast999/Projects/2013-02-02165432_zpsaac09fa2.jpg)

(http://i22.photobucket.com/albums/b316/GreenBeast999/Projects/2013-02-02165445_zps036faf9d.jpg)

(http://i22.photobucket.com/albums/b316/GreenBeast999/Projects/2013-02-02165515_zps167e3cf4.jpg)


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on February 04, 2013, 03:12:30 PM
lincs, i don't know if we've covered this, but how big is the opening at the bottom of the baffle?
I've currently got mine at 100, ready for an 30-50mm ash bed and then 50-70mm air gap


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on February 09, 2013, 02:17:12 PM
finished the protoype!

Here is the firebox burning away
(http://i22.photobucket.com/albums/b316/GreenBeast999/Projects/2013-02-09132526_zpse71024ff.jpg)

Here you can see in the port ive added at the rear, in the backbox
(http://i22.photobucket.com/albums/b316/GreenBeast999/Projects/2013-02-09132540_zps24091083.jpg)

Here is s hole at the top of the backbox, flame present here and measured 715C
(http://i22.photobucket.com/albums/b316/GreenBeast999/Projects/2013-02-09132556_zps6a1f5999.jpg)

I expect the presence of so much flame in the back box, and in fact quite high up the firebox once it got going, is because i've fitted no fire rope yet to seal the lid and the door, also the baffle is just tacked in place, hence air can get in the top and pass aroud  the full height of the baffle to a certain extent.
I will let it burn down and add rope next, probably tomorrow now.

Overall i'm well pleased. it was easy to light by priming the flue with a newspaper fire in the back box.
Next big job is to experiment with boiler options in the back box.


Title: Re: DIY wood burner with boiler???
Post by: rogeriko on February 09, 2013, 03:01:41 PM
This is what I use couldnt be simpler. 2 holes and mount it vertically in the back box so the flames surround it on all sides. 65 pounds on ebay (back boiler) or make one.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on February 09, 2013, 03:44:06 PM
yes, that was gonna be my first attempt, just a box of water



Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on February 09, 2013, 05:29:34 PM
I've added rope now, and it's woefully under 'aired' now, i practically have to have the door wide open to get a good clean flue gases ad decent heat.

So i'm thinking my air intake near the bottom isn't enough, i'll have to add more holes


Title: Re: DIY wood burner with boiler???
Post by: Brandon on February 09, 2013, 08:20:34 PM
GB, give yourself the opportunity to have air inlet equal to that of the CSA of the flue when the air is wide open, you can always temper it with a slider.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on February 10, 2013, 01:54:52 AM
ah ok, so I've got a 5" flue, do i need air inlets equal to that in area?


Title: Re: DIY wood burner with boiler???
Post by: Heinz on February 10, 2013, 09:44:10 AM
No. Mine has a six or seven? (can't remember which) flue and the air inlet is about four inches, reduced to 1/3 of that or less for normal running. It is good to have a large intake for getting a stove going.
My house stove has an 8 inch flue and four one inch inlets. When lighting it, it helps to crack open the door a tiny bit which tells me that the four one inch inlets are a bit too small.

H


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on February 10, 2013, 09:54:10 AM
great thanks!


Title: Re: DIY wood burner with boiler???
Post by: mike7 on February 12, 2013, 07:26:01 PM
Re air intake aperture - the taller the flue you have, the greater the draw. The greater the draw the smaller the inlet you will need - and the more energetic the inflow of air will be. The more energetic the inflow is, the more turbulence there will be in the firebox, tending to give more complete combustion. All of which means that a tall flue is a Good Thing.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on February 12, 2013, 07:38:05 PM
thanks for that, i will bear it in mind. there's quite a short flue on this version but i'm planning for much taller in my caravan


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on February 19, 2013, 08:13:16 AM
I've increased the air intake and also double the flue length, (now about 3m, but does include a double 90deg)

I've built a little water jacket, it really is little, i calculated it at 750ml! Got holes drilled in the workshop wall yesterday, cylinder elevated and header tank in position.
Hoping to get some plumbing bits this week and get the boiler hooked up for a test run this weekend.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on February 23, 2013, 10:38:52 AM
having a nightmare welding up this boiler, can't get it to stop leaking!


Anyway, i've been giving thought to the boiler situation, i'm wondering if, given the boiler-in-back-box idea actually affords us another opportunity. That of choosing whether to use the boiler or not during stove use.

My thining is that one could have a moveable damper that would shift the flue gas/secondary flame to one side of the back box or the other, one side containing the boiler and the other empty and clear.
Sure they'd be some residual heating of the water even in non-boiler mode but it could be handy if the cylinder is up to temp and you still need room heat

Thoughts?


Title: Re: DIY wood burner with boiler???
Post by: Heinz on February 23, 2013, 07:51:07 PM
Welding tanks etc. Prep the edges, grind off the millscale and if the steel is thick bevel the edges. Grind back the end of each weld run so the next run is overlapping the end of the previous run. If a seam has multiple leaks or the weld looks at all snortery, don't mess about adding weld on top of it, grind it all back out and do it again.

Re. the movable damper. Good idea  ;D Friend of mine has a similar setup for his open fire back boiler. Simple baffle sends the heat round the water tank or bypasses it.

H


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on February 23, 2013, 08:13:32 PM
My old Esse range cooker had such a baffle, sending the heat to cooker or the boiler. Worked well enough.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on February 24, 2013, 08:27:48 AM
Thanks heinz, might have another bash today

Good to hear my idea might work. Of course i know how useful it will be. The caravan might be so well insuated that whenever it's alight i need hot water.


Title: Re: DIY wood burner with boiler???
Post by: Lincsoldbird on February 24, 2013, 07:46:34 PM
I find a stick welder better than mig for tanks, being a boat builder I,ve made the odd one or two in my time.
I test mine to 5 PSI and use washing up liquid to find the leaks.
Only had one in 15 years that did not have a leak so don,t dispair.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on February 24, 2013, 09:10:04 PM
all i've got is a stick welder! :)

finally got it leak proof today, got it installed and fired up, took the water from 4C to 40C in 5 hours.
Bear in mind the cylinder only has 1" insulation and is sitting outside (temp 0C)

I'm trying to think how a few inches more insulation and having the cylinder at 'room temp' would affect the performance.


Title: Re: DIY wood burner with boiler???
Post by: Greenbeast on February 26, 2013, 12:19:54 PM
ok based on help from dhaslam i'm going to double the surface area of the boiler and try again