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Post by kees57 on Oct 3, 2017 11:29:05 GMT -8
In that case, the cross section area of your rocket heater is rather limited, about 110x110 mm. Can't be helped, too small remains too small however much used. To overcome that limitation I have designed a electric shimney fan, extra nice about that is I can make draft when cold for startup, shimney fans are expensive so I do make one myself, afcouse save with regulator for draft adjuistment, this way it is done also with normal stoves and seems to work. The rocket sees then a bigger channel, maybe even 20 inch can work, when not I have to replace the pipe inside the old shimney who is big but leaks. O yes something else, I read the burn tunnel needs smaller then the riser, I did however not read it in the books I did buy some time ago, who is been seen as the way to go. Thanks for reaction. kees |
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Post by peterberg on Oct 3, 2017 11:53:53 GMT -8
Yes a fan, inline or not, will do the trick. I tried a complete 150 mm batchrocket system, bell and all to vent through a 100 mm chimney pipe aided by a small tuned-down inline ventilator and it worked like a charm.
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Post by kees57 on Oct 5, 2017 5:32:13 GMT -8
Yes a fan, inline or not, will do the trick. I tried a complete 150 mm batchrocket system, bell and all to vent through a 100 mm chimney pipe aided by a small tuned-down inline ventilator and it worked like a charm. Thanks for advice. You have insert the vebntilator into the pipe, maybe even in a room in stead of the roof? I have drawn a ventilator with a 24 cm 8 blades horizontal blwoing fan (Radial), better is calculate it but have no formulas for that and I do not now yet what the fan does, because it is a whole own design, outside dimensions is 26 x 26 cm. buy one goes into the 1000 euros, and at least the cheaper ones does 600 euros. So make one is quite interesting. PS the batch rockets are very nice, I have a metal woodstove now, a old one I have rebuild with heated air tubes and a ceramic blanket above it for insulation. do well. www.youtube.com/watch?v=TUeDcHuj2ZsUnfortanely I can not upload sketchup file or pictures to this forum, it exceeded his quotum, needs to be clear up.. regards |
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Post by jazeke on Oct 21, 2017 2:35:45 GMT -8
Thanks, Peter and everyone for all your hard work. I have been in the process of building a large batch box heater in my back yard and was wondering if the batch box can be enlarged, i.e., keeping all other dimensions the same for a given configuration, can I widen and/or deepen the batch box in order to increase the amount/size of wood I can load and to also increase the fire viewing window that I plan to put in the door?
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Post by peterberg on Oct 21, 2017 11:11:25 GMT -8
Depth of the firebox can be enlarged to 125% of the recommended figure without repercussions. It will be harder to lit in font of the port though. All other dimensions respected as recommended. Larger glass viewing windows are possible but that's limited by the size (height/width) of the box.
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Post by jazeke on Oct 25, 2017 22:12:50 GMT -8
Thanks, Peter. Would lighting of the larger firebox be improved if the depth were increased by a larger factor? It seem that the longer tunnel might help while also allowing one to use larger pieces of wood.
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Post by peterberg on Oct 26, 2017 0:22:30 GMT -8
Increasing the depth by a larger factor would make lighting in front of the port harder since one need to reach farther to the back of the firebox. I tried a 50% depth increase and found it very hard to light it properly. A longer tunnel won't help at all and the risk of overfuelling is increased as well.
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Post by Orange on Oct 26, 2017 3:03:24 GMT -8
Peter, are the slope bricks in the firebox for easier 2nd fire start or they have other purpose?
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Post by peterberg on Oct 26, 2017 5:46:37 GMT -8
The sloped sides are there for concentrating the glowing coals together in the middle at the end of the burn. Otherwise with a flat floor the coals are spread out and won't burn to ashes properly. Also, the sloped sides are part of the design in that when omitted the firebox would be larger than recommended.
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jeffs
New Member
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Post by jeffs on Nov 1, 2017 20:15:28 GMT -8
Peter, I've been researching RMH info for a couple of years and I must say the information that you have provided here over the years is the most complete I've found anywhere. Thanks for all your work. I've waited until I thought I had enough information and now I am going to start my "Batch Box" heater immediately.
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Post by esbjornaneer on Nov 4, 2017 0:21:20 GMT -8
Thanks, Peter and everyone for all your hard work. I have been in the process of building a large batch box heater in my back yard and was wondering if the batch box can be enlarged, i.e., keeping all other dimensions the same for a given configuration, can I widen and/or deepen the batch box in order to increase the amount/size of wood I can load and to also increase the fire viewing window that I plan to put in the door? Interesting to see Peter's answer to this post here. I asked him the same in a personal message. The jist of the answer I got is that it is best to keep to the dimentions in the spreadsheet as a longer fire box gives the same amount of heat while burning more wood in the process. I take it both answers are correct  |
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Post by smartliketruck on Nov 4, 2017 13:06:33 GMT -8
Interesting to see Peter's answer to this post here. I asked him the same in a personal message. The jist of the answer I got is that it is best to keep to the dimentions in the spreadsheet as a longer fire box gives the same amount of heat while burning more wood in the process. I take it both answers are correct Is this an equal amount of productive heat due to a less efficient burn, or does increasing the firebox depth cause a higher peak output or a longer burn? |
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Post by Orange on Nov 4, 2017 13:26:58 GMT -8
my guess it that a bit longer firebox enables just a bit longer sticks and a bit longer burn at the same rate.
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Post by smartliketruck on Nov 4, 2017 14:15:31 GMT -8
my guess it that a bit longer firebox enables just a bit longer sticks and a bit longer burn at the same rate. Yes that would be my guess also, but hearing from someone who has already charted those dimensions would be good. I'm making my form to cast a 4" (100mm) to burn mostly stickwood bundles of willow and alder. So increasing burn length as much as possible for a low mass heater would be of great benefit. |
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Post by esbjornaneer on Nov 6, 2017 0:47:51 GMT -8
This is what I should have done from the beginning: Below is Peter's reply to me, including the way I phrased the questions. Peter I hope you are OK with me re-posting this. Please remove it if you wish. I just looked back at your youtube video "Batch box rocket stove 10" (https://www.youtube.com/watch?v=YAFhFPdwYss) and it seemed to me that the wood you put in does not reach back to the glass/door. Am I correct about that observation? Yes, that's correct. In fact, the fuel is about 4"shorter than the total depth of the firebox so there's roughly 2" space between the fuel and the back wall as well as fuel and glass. Many of us that have 'replicated' you batch boxes have chosen to make them longer to have less wood cutting to do, and I use logs the full length of the (extended) fire box. Is that false economy, are we loosing efficiency by doing that? And should the logs not be taking up the full length of the fire box? Yes, it's false economy, you are diminishing efficiency by doing that. By keeping it shorter you'll obtain just as much heat from a lower volume of fuel. Interpret it as you wish. As it says in my second question, I did increase the length of the fire box but will keep to recommendations in future (re-)builds. |
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