Anne Christgau

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since Feb 10, 2015
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Recent posts by Anne Christgau

bob day wrote:These are some comments from      as you know, a batch monster is different from a j channel, so you may need to rethink any changes

The correct sizing of the bell was hard won by experimentation, and like all open source projects contributions came from many different people. Klemen Urbanija from Radomlje, Slovenia found out after a lot of tinkering that a 15 cm (6") system with a single bell with an internal surface area of 6 m² (64.6 sq ft), excluding the floor, gave an exhaust temperature 60 ºCelsius (140 ºFahrenheit). He built his experiment outside the house and changed it several times until the results were satisfying, then he tore it down and moved it inside the house. A new round of problems emerged due to the chimney stack being made of bricks, which extracted heat from the exhaust thereby killing the draw. This needed more tinkering and rebuilding of the bell in order to raise the exhaust temperature and restore the draw. The final result was a figure of 5.3 m² (57 sq ft) of 'heat absorption area'. This is important to grasp, and once grasped it can be seen that the floor area of the bell will not be part of the 'heat absorption area' as the flue exits above it. Equally, if the firebox is built into the bell then the surface area of the firebox within the bell won't play a role in calculating this area as no heat is absorbed there.

The term we use for the total area available for heat absorption within the bell is ISA, short for Internal Surface Area. As noted, this does not include the floor area as that floor does not (directly) absorb heat. The difference between a steel bell which is shedding its heat immediately and one that is storing heat in a mass of stone or brick is marginal in terms of ISA. My workshop heater (see article Three barrel batch rocket) is built out of three oil barrels which together are very close to the same ISA as Klemen's masonry bell and bench. Both systems have a comparable exhaust temperature.

Scaling up of these numbers posed a long-standing problem which was finally solved in 2015. It turned out that the same critical dimension used to scale the size of fireboxes up or down, the cross sectional area of the heat riser, can also be used to scale the bell ISA up and down from the base result determined by Klemen. 2015 was the year that the bell with two cul-de-sac benches was built during the MHA meeting (see article Bell with dead-end benches). The maximum ISA of that 20 cm (8") system and a masonry bell without chimney bypass turned out to be 9.4 m² (101 sq ft). The ratio of Klemen's heat riser CSA to the MHA riser CSA was 1 : 1.77, and the same ratio of 1 : 1.77 appeared in both ISAs. We had found it!

As a consequence we can use the following 'table', and simply extrapolate or interpolate as required. As far as we know, this method works within reasonable limits in both directions.

Riser diameter   /   Internal Surface area

   12.5 cm  (5")   ISA 3.7 m²    (39.8 sq ft)
   15.0 cm  (6")   ISA 5.3 m²    (57 sq ft)
   17.5 cm  (7")   ISA 7.2 m²    (77.5 sq ft)
   20.0 cm  (8")   ISA 9.4 m²    (101 sq ft)
   22.5 cm  (9")   ISA 11.4 m²  (123 sq ft)
   25.0 cm  (10") ISA 14.7 m²  (158 sq ft)

Thankyou Bob for the brief history, re Batch Box and sizing. I copied Peter V D B Minnie Mouse Stove as far as I could from photos and sizes he gave. All was good. I take on board what you say re batch box and will leave that to the not too distant future ( tongue in cheek). Thanks again
1 year ago
Morning Paul Thanks for the photos of Minnie Mouse. Sorry we have none of our hut stove, My build was very messy and it worked well. But the fitting of the firebox and riser into the barrel was a bit makeshift even I have to admit, so Peter has removed the firebox and riser ( he has just told me) refining them as only you men can do!!!. And then putting in the bricks for mass. Should Bricks be all fire bricks, or firebricks lower down and ordinary ones above. I think we will be giving the batch box a miss for the time being, but it's not out of our mind. I will take photos and post them to you when all is done.

1 year ago
Many thanks for remembering Paul. In Fact when there were no replies I emailed Peter in Holland and he came up with some answers.
It's installed in my hut. J tube at present with no brick lining as yet. Working like a little wonder. Am thinking of making a Batch Box. With casserole door. I hope I can get away with using the same barrel. 45 Gallons English measurement.
, what do you all think.
I hope your Jamboree went well.
All the Best
1 year ago
Good Morning from across the pond. My first post on Rocket Stoves, Hello to all.
I have a small hut 7' 6" x 18'. No insulation to date. Old wood stove has finally collapsed.
Am very interested in the Minnie Mouse heater / stove, 4" J style in bell, built by Peter Van de Berg at a get together in Montana, have searched the net For more information without success, only one or two photos and a brief description of build by Peter on this forum. Ianto Evans book does not show such a build. It seems to be a relatively easy build for me bearing in mind age and physical ability. Most important it has a small footprint.
Three questions.

1) For the 'Minnie Mouse' Can I use a barrel smaller than the 55 gallon mentioned and still line it with brick for internal mass?
2) I have read that the heat riser is cut down, how far should it come towards the top of the barrel?
3) Alternatively if I cast a 4' batch box for the 'Fat Rabbit' how far could I reduce the size of barrel?

Be most grateful for any advice am not up to speed with the maths or science.
2 years ago
Good Morning from UK.
If you live in London everything is at a great price, you name it, you can get it but it will hit your pocket.
Salvage firebricks are expensive, although the more you buy the cheaper they are.
I live in South East London and most of the old buildings are made from yellow stock. Not much soft red around
and what there is is bought by architectural salvage companies.
Is it possible to make a temporary kiln that will last for one firing? Something simple enabling you to cook your bricks?

Good Luck and if I hear of anything will message you.

2 years ago
Many Thanks for your replies, suggestions. We rent our container purely for storage
but the condensation gets out of hand. Buying a container may seem like a
cheap option for housing / storage etc, but when you factor in insulation etc it is
not ideal.
Thanks again
2 years ago
Can anyone advise me on how to reduce the condensation inside
an unlined unheated container?
2 years ago
Hello, it may be suffering from dwarfism, not much you can do about this, other than talk to the breeder,
Bantams are usually quite tough little birds despite their size. But it is worrying for you.
A rabbit hutch is not ideal, and it is essential that in their coop they have a branch that they can perch on during the night,
about two feet off ground they will feel so much safer than huddling together and not feel the drafts so much.
All the best

2 years ago

Joy Oasis wrote:I love adding nettles to my green juices, smoothies, making nettle pesto, soups, and tea. I use rubber gloves to handle them until they are cooked or blended. However, do not overdo on them. I did eat them daily and after 2 weeks my neck started itching and I got full blown eczema after one more week until I finally understood the culprit.

Good Morning from across the pond. When I was a little girl 70 or more years ago, I lived in Gloucestershire, sometime we had to pick nettles to sell, I think to Herbalists or the like,
we'd start out with great enthusiasm cutting the nettles and watching the pile get higher and higher and getting very excited in anticipation of all the money we would earn, then off for tea break,
and oh disaster when we returned to find our big pile completely diminished, of course they had wilted through, so disheartenening for one so young.
Also My Grandmother would never have to wear gloves, she would pull them up from the base under the leaves
you dont get stung, well she didn't. If we were stung there was always an abundance of dock leaves to rub on. Nettle soup as Joy writes is great and very very young fresh nettles are good in salads.
2 years ago
Hello from across the pond,

At our local park in South East London lichen can be seen growing on the tarmac paths
At first I thought I was looking at gobs of chewing gum, on closer inspection lo and
behold lichen.
2 years ago