Julian Adam

Incredible result, congratulations Peter & helpers! Are they topping it up all day long to have sufficient heat output? Almost a pity to cover it in clay plaster!

beautiful result, cedric, also an aesthetic improvement in my opinion!

Peter van den Berg wrote:
The ISA for the Shorty core is down to 85% of the recommendation for a first generation core.

That's what I thought, thanks for confirming Peter!

Peter van den Berg wrote:
Tried last month with the large heater in the Sculpter's shop  
and it works beautifully

I've been following your posts closely, wat een prachtige mammoet! Makes me a little sad I cannot find the time to finish my own. Looking forward to the rest of the sculpter build!

thomas rubino wrote:
I built mine using the ISA numbers for a first-generation batchbox. After hearing the temperature numbers I  was receiving, Peter lowered the ISA numbers on Shorty.

This I was completely unaware of, or must have forgotten already!
FYI, about the condensation, it also contains sulphur, making it acidic. For biomass combustion, it's a major concern in terms of low temperature corrosion (I'm following this up at work). 'Clean' wood contains little to no sulphur, or chlorine (so it's not like your chimney will get holes within one or two years) but it may still cause corrosion over time. Coincidentally (or Peter is aware), the 90 °C in the chimney I've seen him mention a few times as minimum is also typically around the sulphur dew point for clean wood - so that 90°C, I would consider completely safe in terms of corrosion.

thomas rubino wrote:
Check this thread out, Julian  https://permies.com/t/361932/Holding-heat-overnight-importance-shutting
Don't add a damper; close off your intakes instead.

I've seen your thread passing by Thomas! It's these kinds of experiments that demonstrate valuable insights. I hope by this time next year I'll be able to contribute something as well. (Unfortunately other renovation priorities still keeping me from finishing the BBR). In my case, the chimney will be within the bell, so inevitably I will be heating the air inside of it with the mass, which I assume will create extra draft and flow through my mass (I'm not yet confident I will be able to weld a fully sealing door, haha)

Being able to close the damper to the flue fully is also forbidden here in Belgium, you are required to leave minimum 15%, up to 25% of the system size free to prevent CO issues. In my case, for a 150mm system size, it wil require a hole of around 60 mm. I'm still doubting installing one, since it's more work, but on the other hand will allow me to decrease any residual airflow through the heater, which has shown to be very important to hold the heat.

A question to you Thomas, hearing about your condensation issue: would you suggest further decreasing the recommended ISA for the shorty? I will only be firing my bbr once a day, so I'd like to avoid condensation.

I will be using calcium silicate board to insulate the outside of my BBR core. It does not contain fibers, but of course you must still be careful with the silica. In my opinion, it is a viable alternative. It does not insulate as well as superwool, but you could go slightly thicker with it (e.g. 5 cm board instead of 2.5 cm blanket), or just accept that it will perform slightly less.
It's also not cost-prohivitive in my opinion.

https://www.broodoven.com/calcium-silicaatplaat-1000x500x50

Rico, Morgan Superwool may be ok to use while not yet exposed to high temperatures, but using it as a riser is, in my opinion, not a great idea. It will be toxic once you have to remove it. keep it for the parts of the heater which are exposed to lower temperatures, and even then tread carefully (especially when dismantling: at least wet it and use a mouth mask). I prefer to see it as a carcogenic until fully proven otherwise.

thomas rubino wrote:Hey Julian, Thank you.
Riser is 36"

Funny how the mind can play tricks, maybe it's the superwool that got me.

Great work Thomas and Gerry!
And thanks (again!) for documenting so well.
I just noticed the height of your riser is proportionally lower than what I have in my head. Are you at 8B length?
Keep it up!

I see you mention tomettes. Are you French(-speaking)? If so, maybe try looking for 'plaque d'égout en fonte ductile'. Based on the fact that the usual barrel over the J-tube can last for many years, I would think this would work well, assuming you put some stove rope / seal in the groove.