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Post by yoorname on Nov 22, 2018 9:30:38 GMT -8
Hello. I've built a Batchstove that has this shape : uzume-asso.org/assets/img/batchrocket_proportions/vues_3D_batchrocket.pngAfter several hours burning, I have to get coal out of the box to get place to put new wood inside. It's quite dangerous as the coals are red incandescent. So I am thinking about adding an ashtray with something that shake the embers to get the ash down in the bin. Has someone invented an ashtray for bachstoves ? (I took a look in the forum searching "ashtray" and didn't find something...) Thank you.
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graham
Junior Member
Posts: 74
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Post by graham on Nov 22, 2018 15:25:54 GMT -8
The coals provide heat in order to burn new wood. And provides more energy from the direct combustion of the coals rather than from burning wood gases.
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Post by wiscojames on Nov 22, 2018 15:31:18 GMT -8
Was the original poster trolling?
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graham
Junior Member
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Post by graham on Nov 22, 2018 19:55:38 GMT -8
No, I don't think so. A lot of modern people are not familiar with how fires work.
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Post by yoorname on Nov 23, 2018 4:12:06 GMT -8
Thank you for answering. Actually I do not want to get the coals/embers out of the stove. I would like to only get the ashes out.
The burning chamber dimensions are : 166x248x420mm. This is not that big. After 3 burns, I mean I've put wood to the top of the chamber, burnt it, re-put wood to the top, reburnt it, one time again (=> 3 burns), I have so much ashes (I do not speak about coals/embers) that I can hardly put new wood inside the chamber.
That is why I would like an advice : how to deal with ashes in such a situation ?
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Post by Vortex on Nov 23, 2018 9:41:32 GMT -8
You could probably make an ash trap by having a half inch slot either side of your P-channel. Though you would need a good airtight door for the ashbox. This is the one I use in the bottom of my new vortex stove:
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Post by drooster on Nov 23, 2018 10:18:44 GMT -8
Peterberg must do three consecutive burns sometimes in his optimised batchboxes, how about asking him what he does with the ashes, and when.
An ashpan might affect some aspects negatively if the batchbox is up to proper spec.
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Post by coastalrocketeer on Nov 23, 2018 11:58:41 GMT -8
That seems like a lot of ash, though I have not operated a batch box myself. What kind of wood are you burning, and do you have a door on the stove?
Photo of the front as it exists, door open and closed, woukd help woth visualizing a solution that could work with what you have there.
I could see making a suitably shaped pan out of sheet aluminum or steel that hooks somehow to, or you hold by a handle at, the bottom edge of the box opening for sweeping the ashes out into...
Like a flat dust pan one would use with a broom, but with the leading edge shaped with the flat bottomed V of your stove core's floor.
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Post by peterberg on Nov 23, 2018 12:01:21 GMT -8
I find it strange your firebox is filling up with ashes. Mine doesn't, I run it in the morning and in the evening, just one load each time. Mostly conifers, sometimes I can lay my hands on oak or birch. I let the coals die down and close the heater. Some coals are still there in the morning and I start a new fire on top of that. Virtually all the carbon is combusted this way, the ashes starting to form clinkers. Lumps of ash that has been fused together so there's a layer of ash in the firebox. Last week I emptied it for the first time this season. The recent development test runs are done on a 120 mm system, built of ceramic fibre board. No build up of ashes to speak of, even eight runs using ash wood didn't.
Now about what can be possibly wrong with your heater. #1 Bark and lots of moist fuel can build up ashes fairly quick. Did you check the moisture content of your fuel and what type is it?
#2 You say you run the heater and refill it two times completely, so I'd think that will be in the course of 3 hours. And you want to refill it once more but the coalbed is enormous by then. You seem to run the heater like a cast iron stove, after three hours of running a batch box the thing should be awfully hot. Maybe you want a lot of power out of a this heater, in that case you've built it too small. Do you know what temperature is exhausting to the chimney during such an extended burn?
#3 What material is your combustion core made of? Since it is a small system the ratio of wall area and volume of the firebox is very unfavourable.
#4 Vortex is right about the way to implement an ashpan, just a slit in the floor plus a very tight closing ash door. The batchbox combustion process will be fatally disturbed by under air supply. The off-gassing of the fuel will get much higher with fuel overload as the result, lots of black smoke out of the chimney.
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graham
Junior Member
Posts: 74
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Post by graham on Nov 23, 2018 12:04:40 GMT -8
The burning chamber dimensions are : 166x248x420mm. This is not that big. So, this is approximately a 4.5 inch batch box? What are you trying to heat with this?
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Post by yoorname on Nov 23, 2018 14:18:58 GMT -8
Thank all of you to answer my question.
If the temperature outside is cold enough, I have to burn quickly several wood loads. That means, burn a full chamber of wood, as soon as there are no flames any more, add another load of wood to the top and do so, let's say, for 3 to 6 times. Then I end up with a big pile of embers.
Later on, if I want to fire up the stove again, I have a mix of red coals and ashes. Removing the ashes could save some space and may burn better with no stifling ashes around them.
For me ashes are the tiny parts of wood that can't chemically be burnt, so they have to be removed by some way...
Stoves usually use a sort of "shake system" to drain the ashes down to a drawer. Maybe the solution would be to horizontal plates, one on the other, each with holes, sliding on each other, once the holes are aligned and the ashes can get down, once they are not and there is no "bottom ventilation". What do you think about that ?
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graham
Junior Member
Posts: 74
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Post by graham on Nov 24, 2018 13:01:57 GMT -8
I think you need to show everyone your whole system. Batch rocket stoves are supposed to dump their heat into mass storage and do burns maybe twice a day to replace the heat lost from the mass. It sounds like you're using your batch stove differently if you need to do 6 burns a day, or your system is undersized for your storage.
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Post by yoorname on Nov 24, 2018 14:37:14 GMT -8
Yes, it is undersized. The smoke coming out the mass heater is around 80°C and it's only steam. So the heater works well (Peter said it in another thread I've opened last March) but less, in size, than the half of what I should have according to the volume of the place/room it heats.
But there is a reason why the stove is too small, the riser could not be higher than 75cm, I am limited in height, I use a 250 litres water heater tank and to keep the spaces needed above the riser and underneath the combustion chamber make that riser cannot be more than 75cm.
Voilà voilà for the story :-) .
But I think that it does not change anything for the ash removal problem, for me an ash drawer simply misses in the design of the stove to be complete/full options.
And this keeps me thinking about it : my secondary air intake lays on the bottom of the chamber (sort of ___| design) not from above. The horizontal tube is heated by the fire coals, if I put a plate between the fire and the tube, it'll miss some heat. A round tube maybe ?
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graham
Junior Member
Posts: 74
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Post by graham on Nov 24, 2018 15:16:54 GMT -8
Have you looked at the riserless cores? The DSR2 and variants? They're not so limiting in terms of vertical height.
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Post by peterberg on Nov 25, 2018 1:36:08 GMT -8
Yes, it is undersized. The smoke coming out the mass heater is around 80°C and it's only steam. So the heater works well (Peter said it in another thread I've opened last March) but less, in size, than the half of what I should have according to the volume of the place/room it heats. So you built it less than half the size you should. Because of that, you tend to feed it semi-continuously which creates the enormous glow bed problem. I would say you let the glow bed die down on its own until it's nearly all black and close the air inlets. That would solve this particular difficulty, I'd say. Creating another problem on the way, not enough heat for the place where it's situated. Looks like riding a Citroën deux chevaux on the motorway and complaining it doesn't do 160 km/h. Looking around for a solution to this alleged problem by adding a turbo charger and an Abarth exhaust system for instance. You read the Uzumé website so you've come across the sizing recommendations of Yasin which says to always oversize, not undersize. This batchrocket design is specifically meant and developed for mass heater purposes. Your 250 liter boiler vessel won't hold heat for long so you are using this combustion core as a bog standard cast iron stove. One could expect it to be absolutely riddled with problems, not just one. It's winter now but the solution, without creating another problem again, would be to build another one. Properly sized, using the DSR2 setup for example which proved to be quite reliable, plus a lot of mass to even out the heat. I am terribly sorry, but I can't see it any other way.
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