Posts : 126 Join date : 2013-12-12 Location : Sheffield UK
Subject: Re: My first rocket stove space heater Thu Mar 06, 2014 7:13 pm
Thanks ppotty. I like that idea as it will save having to get the sand out after each firing. The reason that I am trying the updraft version is because it is easier to light, as I had difficulty persuading the flame to go down and I had lots of smoke coming into the room when lighting it. An ideas?
hermetic
Posts : 19 Join date : 2014-02-18 Age : 71 Location : Driffield, East Yorkshire.
Subject: Re: My first rocket stove space heater Thu Mar 06, 2014 8:09 pm
You could create an ashpan in the bottom, and light from the bottom, as in the commercial version, the heat from the ashpan fire would get the flue going and draw air down from the top as the flue warmed up.
2ndburn
Posts : 165 Join date : 2013-12-05 Age : 64 Location : shropshire
Subject: Re: My first rocket stove space heater Thu Mar 06, 2014 8:20 pm
. Hi James,
Try using a front Break disk /rotor taken from a large car or van ?
ppotty1 Admin Admin
Posts : 241 Join date : 2013-09-30
Subject: Re: My first rocket stove space heater Fri Mar 07, 2014 7:51 am
jameshookway wrote:
Thanks ppotty. I like that idea as it will save having to get the sand out after each firing. The reason that I am trying the updraft version is because it is easier to light, as I had difficulty persuading the flame to go down and I had lots of smoke coming into the room when lighting it. An ideas?
If I was creating a sawdust burner rocket I would burn and draught from the bottom. I would form a wire mesh tunnel around 4x4 inch from the ash clean out into the riser entrance then fill with sawdust and light from ash box, with that weighted plate on top of the sawdust it would help to force the load down onto the burn tunnel. Wire tunnel mesh around an inch for first test then reduce or enlarge as needed. It should burn like crazy.
Maybe just cover mesh with piece of newspaper when filling firebox to stop tunnel filling up with sawdust.
would not compact sawdust in firebox, keep it loose as it would burn better.
hermetic
Posts : 19 Join date : 2014-02-18 Age : 71 Location : Driffield, East Yorkshire.
Subject: Re: My first rocket stove space heater Fri Mar 07, 2014 8:41 pm
Hi ppotty, that sounds like a very workable ides to me! the mesh would have to be fairly tough to stand the blast furnace effect, but of course, would be easy to replace anyway. Is providing a throttle on the air inlet a good idea on a rocket stove? I can imagine that with an unlimited amout of air, a sawdust fed rocket could star sucking so hard that it would carry the fuel into the rocket itself, and quickly overheat, or cause a collapse in the sawdust chamber, and choke it up. What do you think? My ex precision engineer(now a skilled woodworker) friend needs some way of heating his newly refurbished workshop, and he is highly skilled in the sawdust and shavings creation industry! Phil
ppotty1 Admin Admin
Posts : 241 Join date : 2013-09-30
Subject: Re: My first rocket stove space heater Sat Mar 08, 2014 12:42 am
hermetic wrote:
Hi ppotty, that sounds like a very workable ides to me! the mesh would have to be fairly tough to stand the blast furnace effect, but of course, would be easy to replace anyway. Is providing a throttle on the air inlet a good idea on a rocket stove? I can imagine that with an unlimited amout of air, a sawdust fed rocket could star sucking so hard that it would carry the fuel into the rocket itself, and quickly overheat, or cause a collapse in the sawdust chamber, and choke it up. What do you think? My ex precision engineer(now a skilled woodworker) friend needs some way of heating his newly refurbished workshop, and he is highly skilled in the sawdust and shavings creation industry! Phil
Hi Phil, Yes I would fit air control anyway, use full draught to get the burn started then adjust to control it for a steady burn. The extreme temps in the riser burn everything down to virtually nothing, having burned alot of sawdust in my new firebox I checked the insides of the stove to find almost nothing inside. When sawdust and shavings burn they form a kind of crust on the burn surface, this tends to hold the pile together and prevent collapse, the dust directly behind the crust gasses off and that's how it burns into the load. you only get a massive flame and burn when you disturb the crust, but it quickly forms again. The wire cage would prevent the burn passage getting blocked should the load suddenly move down. A weighted top if designed right would also move the load down at a steady pace preventing sudden collapse. Another reason why not to pack the load too tight so it can move freely and burn better.
I will stick my neck out and say you could probably have the fuel chamber as big if not bigger than the actual heat exchanger on the stove, and I'm thinking 55 gall drum fuel store with large gas bottle exchanger. I have no idea but maybe a 24 hr burn ? if set up right.
Last edited by ppotty1 Admin on Sat Mar 08, 2014 12:52 am; edited 1 time in total
jameshookway
Posts : 126 Join date : 2013-12-12 Location : Sheffield UK
Subject: Re: My first rocket stove space heater Sat Mar 08, 2014 12:48 am
I have started to build a new sawdust burner and will get some photos as soon as I have a first burn. Thanks for the help. James
ppotty1 Admin Admin
Posts : 241 Join date : 2013-09-30
Subject: Re: My first rocket stove space heater Sat Mar 08, 2014 12:54 am
Look forward to it James.
hermetic
Posts : 19 Join date : 2014-02-18 Age : 71 Location : Driffield, East Yorkshire.
Subject: Re: My first rocket stove space heater Sat Mar 08, 2014 1:13 am
Thanks Ppotty, some good info there! I will let you know what happens, and get a build on the site soon I hope, I am a bit spacially challenged at the moment as I am still working on my workshop rebuild project which I hope will be finished by May! Phil.
gadily Moderator
Posts : 1477 Join date : 2013-12-08
Subject: Re: My first rocket stove space heater Sat Mar 08, 2014 8:31 am
ive looked before and could only find 8hrs burn time however i bet if you changed the height of it then you would get much longer
but not sure id its the width that would be needed
jameshookway
Posts : 126 Join date : 2013-12-12 Location : Sheffield UK
Subject: Re: My first rocket stove space heater Sat Mar 08, 2014 9:37 am
I wanted to do an 8 hour burn so that it will last a working day
twistedkarma
Posts : 178 Join date : 2014-01-04 Location : East coast USA
Subject: Re: My first rocket stove space heater Sat Mar 08, 2014 12:07 pm
james, how I get my chips to burn in my hopper.
I light a fire at the bottom, in the riser.
Then add chips , covering over them, air is still getting through, and drafting . then I light the top of the chips. and let them burn down. the bottom burn eventually goes out, lack of oxegen.
mine had a smaller top opening in my hopper.
hope this helps.
jameshookway
Posts : 126 Join date : 2013-12-12 Location : Sheffield UK
Subject: Re: My first rocket stove space heater Sat Mar 08, 2014 7:19 pm
sounds interesting. `do you have any photos?
twistedkarma
Posts : 178 Join date : 2014-01-04 Location : East coast USA
Subject: Re: My first rocket stove space heater Sat Mar 08, 2014 10:14 pm
I start the wood the same way, get it going at pinch point of start of riser, and keep adding wood, fire will burn out into hopper, and 45 degree bottom will let coals fall into base area at foot of riser, and act as a reburn area for smoke , I have a ash door, that gets cracked open down there, that's my secondary air. could you twig light yours and dump sawdust in? I know that large top must give you a room full of smoke when open.
My new build smoked me out, this morning, I was able to light up , and fully load without a lot of smoke, I twig built right at my exit, and worked away from the pipe, piled it full. I think I will try this for a couple of days. and not fill while in use. after I build the riser into the vessel, i'll do the burn test btu thingy.
jameshookway
Posts : 126 Join date : 2013-12-12 Location : Sheffield UK
Subject: Re: My first rocket stove space heater Sat Mar 08, 2014 10:44 pm
Yes, the large top is the problem with the smoke. I am thinking about putting a small hatch in the lid to feed wood through.
jameshookway
Posts : 126 Join date : 2013-12-12 Location : Sheffield UK
Subject: Re: My first rocket stove space heater Sat Mar 15, 2014 9:52 am
This is my first firing of my large saw dust burner.
The idea is to get a log burn time, but it only burnt for an hour and a half despite topping it up half way through! It did pump out the heat though the temperature on top of the heat exchanger exceeded 550C (1022F) far too hot!!!!
I would like to know how to reduce the heat. Any ideas welcome.
As you can see there is a small door 3" x 6" with one inch holes.
There is a metal frame going through from the door to the chimney which melted with the heat.s875.photobucket.com
twistedkarma
Posts : 178 Join date : 2014-01-04 Location : East coast USA
Subject: Re: My first rocket stove space heater Sat Mar 15, 2014 12:56 pm
don't cut heat, put a 200 gal tank right next to it, convex so it wraps around heat exchanger, staying away from it for 4 inches to keep from boiling?
or is space a issue.
Run chips or wood chuncks to slow it down?
hermetic
Posts : 19 Join date : 2014-02-18 Age : 71 Location : Driffield, East Yorkshire.
Subject: Re: My first rocket stove space heater Sun Mar 16, 2014 8:10 am
I think you are exposing too much sawdust to the fire at once, and getting a burn over the whole base of the burn chamber, look at the design of this one, which does burn upwards, not downwards as you are trying to do, but I think you will see that the sawdust at the bottom of his burn chamber is only exposed and only burns from the hole upwards (and outwards slowly) If you could let the air in at the top of the burn chamber via an air pipe from the bottom, to stop it smoking, and draw the air down through a bottom hole and then into the secondary chamber, it may burn more slowly and "rocket" as well.
Posts : 126 Join date : 2013-12-12 Location : Sheffield UK
Subject: Re: My first rocket stove space heater Sun Mar 16, 2014 8:42 pm
Hi Phil,
Having done a top down sawdust burn in this stove (see photos earlier in this thread) although the surface area starts small it soon increases to an area larger than this burn. Having just looked back at the photos I have noticed that the exit hole is only 3", so maybe reducing the pipe going into the heat exchanger will help, as at this moment it is around 5"
Thanks for you thoughts
James
jameshookway
Posts : 126 Join date : 2013-12-12 Location : Sheffield UK
Subject: Re: My first rocket stove space heater Sun Mar 16, 2014 8:48 pm
twistedkarma wrote:
don't cut heat, put a 200 gal tank right next to it, convex so it wraps around heat exchanger, staying away from it for 4 inches to keep from boiling?
or is space a issue.
Run chips or wood chuncks to slow it down?
I like your thinking, but it is not my workshop so I don't think that my friend would go for it.
I may try wood chips of mix chip and sawdust.
hermetic
Posts : 19 Join date : 2014-02-18 Age : 71 Location : Driffield, East Yorkshire.
Subject: Re: My first rocket stove space heater Sun Mar 16, 2014 9:50 pm
Hi James, Do you have sketchup? I think I may have an idea which might work, but it's a bit difficult to describe, would be easier if I could post up a sketchup file! Phil
hermetic
Posts : 19 Join date : 2014-02-18 Age : 71 Location : Driffield, East Yorkshire.
Subject: Re: My first rocket stove space heater Sun Mar 16, 2014 10:50 pm
Well I would if I could get this forum interface to accept jpegs and sketchup files, and to preview, and then go back to upload without losing everything I just typed, back to the FAQ
hermetic
Posts : 19 Join date : 2014-02-18 Age : 71 Location : Driffield, East Yorkshire.
Subject: Re: My first rocket stove space heater Sun Mar 16, 2014 10:58 pm
Hi again James, if you PM me I will send them to you as there seems to be no way of uploading files? Ho hum:-(
hermetic
Posts : 19 Join date : 2014-02-18 Age : 71 Location : Driffield, East Yorkshire.
Subject: Re: My first rocket stove space heater Sun Mar 16, 2014 11:02 pm
PM me with your email address that is, the "contact member" pm is equally recalcitrant
gadily Moderator
Posts : 1477 Join date : 2013-12-08
Subject: Re: My first rocket stove space heater Mon Mar 17, 2014 8:16 pm
jameshookway wrote:
Hi Phil,
Having done a top down sawdust burn in this stove (see photos earlier in this thread) although the surface area starts small it soon increases to an area larger than this burn. Having just looked back at the photos I have noticed that the exit hole is only 3", so maybe reducing the pipe going into the heat exchanger will help, as at this moment it is around 5"
Thanks for you thoughts
James
the thing i see is that you have changed the way its supposed to burn as your original idea was like a j tube just much higher the problem with having the fire and holes at the bottom is that you burn much quicker unlike your other top down version
on your previous version any attempts to open it will produce smoke out at the top and is best left to burn out after lighting
the illustrated video burns from below and goes back down like a rocket burner does therefore produces an 8 hr burn time ppottys version gives 2-4 hrs burn time and is much smaller 15"-18" in height id take another look at his version and produce it around that james