Julian Adam

Congratulations Tony! Seeing your finished product, I was wondering if you went through a lot of trouble separating the glass panel from its attachment points to the rest of the cooking hob? Seems like they often have the attachment points glued to them.

Denise Cares wrote: There is no diagram or explanation of the design. I thought I'd share it with Permies RMH experts and would like to know what you think of it. Is it practical and efficient and might it pass building codes in most states/countries?

As far as I can tell it is a Kuznetsov stove design with the corresponding 'dry seam'. (a lot) more complex to build over a batch box rocket with hollow bell, and I believe Peter did some testing to show that the efficiencies are not as high as a BBR.
You can find the Kuznetsov designs online as well. They use russian brick sizes though, which I believe is a problem.

I would like to add to Glenn; if you are using the buildup with insulation under the slab, if you have the option, it's best to use XPS or EPS. Especially XPS does not suffer from moisture, PUR (nowadays the standard insulation, at least here in the EU) does. I will be using XPS for my underfloor heating (backup/alternative to my RMH).

Matthias, if I may quote Peter, a bit higher up in this thread:

Peter van den Berg wrote: The DSR3 is a nice one, very spectacular to see it burn. Although complicated to build, some materials aren't available everywhere. But it is as self-regulating as a Shorty core which development followed logically after this one.

I read self-regulating as you don't have to do any fiddling with the air intake - it 'decides' itself to dampen the air intake. As I understand, most people don't touch the air intake on batchrockets, probably just loosing a few percents in efficiency. But you can hear what Peter has to say on the matter.

Scott Weinberg wrote:
Being that I built into my  7" sized bell with related ISA  measurements, a very simple 8" dia inspection door that takes all of 10 seconds to slip off and inspect the insides, I found exactly as Peter mentioned.

Thanks for adding your experiences to this thread Scott!

Peter, I've started my build a few months back: https://permies.com/t/261401/BBR-inch-mm-sidewinder-build
Unfortunately I don't have enough free time to continue building as quickly as I'd like, giving too much time for thinking...
With 'my original question to you' I meant in my build thread, I asked about the 5 times CSA clearance around the core, and after your input I increased the clearance to around 7.5. The external skin is built now. Using the shorty core instead of the original batch box, I would be sacrificing some of that clearance again due to the deeper port, to around 6.1 times riser CSA. My sketch was not sufficiently clear.

Forgive me for sharing my thoughts:
If I'm using the shorty core, I could keep the door in the middle, but there will be a 'slit' to the right of the core which I probably shouldn't count as clearance around the core. Plus the hot gas would directly be aimed at my chimney.

Other option is to put the door at the right side of the bell, then I would be able to use the ful 6.11 x CSA clearance. Only concern would be 'side gap' (eq. to top gap for shorty) of around 20 (assuming some extra mass / insulation where the gas hits the bell's wall) - 24 cm, which is less than the recommended 2 x system size.

Peter van den Berg wrote: Most of the time there are three steps:  door open a crack to start with, door open half a crack (step1), door closed (step2), partially close the air inlet (step 3). With half a load step 3 is left out, the exhaust temperature will be stable by itself in that case. Time isn't the factor to go by, always the exhaust temperature. This a result of testing this heater endlessly, there seemed to be a direct correlation between chimney temp on the one hand and performance in terms of highest efficiency and lowest CO level on the other.

Great explanation, if I understand correctly the temperature at which to perform step 3 will be dependent on the construction of the heater / bell.

Peter van den Berg wrote: No problems with the sidewinder Shorty core, it runs beautifully. I tested it last July during a workshop and it performed just the same as a straight one. A couple of guys tried to overload the thing for hours on end and they didn't succeed, not even with a reload right in front of the port. It was a strange sight while I walked to the workshop site, saw nothing leaving the bare chimney pipe only to be met with a heater that housed a huge, roaring fire. Such moments, I became unresistable giggly and felt very, very satisfied. No wonder, its development took the best part of a year, after all.

I can imagine, at these times, it probably almost feels like you are defying the laws of nature! I must come back to my original question to you, Peter. That is, do you think the shorty sidewinder could be incorporated in my bell? My concern being that the flue gas flow coming from the riser may obstruct the downwards stratifying layers in the bell?

Peter van den Berg wrote: 2 to 5 degrees C, nothing much to speak of.

This is indeed very little, thank you for clarifying.

Peter van den Berg wrote: A complicating factor is the fact that I am used to tuning the heater down with the air inlet during the burn, in order to keep the exhaust temperature below 120 ºC (248 ºF). Between 100 and 110 ºC (212 and 230 ºF), while the roar is unaffected is very close to ideal. This is one of the things I tried very hard to have it built-in with the Shorty core, it is meant to regulate itself, independent of the air supply. That's why the Shorty is a casual burner, burning clean with a high overload resistance and good hot refueling characteristics.

I have two additional questions, sorry! :)
1. If you say you tune down the air inlet, how often do you have to play with it? Is it just closing to x percent after x time once?
2. I can see the advantages of the shorty core. My bell will be high but the shortness appeals to me because if the regular sidewinder core would ever need replacing I would be up for a (huge) rebuild, because of the tall riser. Only recently I discovered that you had mentioned the build of a sidewinder shorty version as well. I was wondering if you tested this version with your Testo? I would assume the lack of floor channel may make the sidewinder less ideal?

Scott Weinberg wrote:
I got behind on my replies, sorry.  

Please don't apologize, there is no need!

Scott Weinberg wrote:
Julian, I presume the gap difference would happen because you want to keep the face of the bricks on the outside flush with each other?  And rightly so, And I think Glen said it well, that things might not be quite as uniform, but... will you be able to really tell?  That is always the question.

You are completely right, I want to keep the outside flush. You are also right that it probably does not matter a great deal, but I'm a bit perfectionist so I like to exclude as much (big) mistakes as possible, knowing full well that once built, changes to my heater will be very hard as it will be in my living room and I have a girlfriend to keep happy..

Glenn, I would definitely be interested in these pictures! I suppose the walls looked similar to the video Hof shared? Thank you for your extra info, scooping out the ashes after a few years it is!