design and building my batch box rocket with creating warm tap water

hello all,
short introduction : i am a belgian architect, constructing my own house.

- maximum possible off the grid sunship house with large greenhouse attachted to the south (wink to the original earthship)
- 175 m2 floor surface ( 1883 sq ft) for 5 people and my own office, one can say a tiny house for each and everyone of us ;-)
- recycled glas shutters for foundation & floors
- wood foundation beams
- prefab strawbales for roof and walls
- wooden windows with triple glazing
- recycling & upgrading all rainfall

heating my house
1st = the sun through the greenhouse glass
2nd = wood from our own trees -  i will build a BBR in the living room/kitchen with direct radiation walls and a bench.
studied a lot of info from this website webpage & had a very nice meeting with the rocket master himself !!
3rd harvesting heath to send to my hot water tank (this can be done through the principle of thermosiphon or with traditional pump)


on top of the riser, i will put a smoke valve to send hot gasses through a well isolated horizontal metal tube
when closed, the gasses drop to the secondary chimney entrance, on ground level.

my question:
to calculate the dimensions of the BBR - do i need to take into account the chimney itself ? 200 x 200 mm (7,8 inch x 7,8inch)
or
do i need to use the diameter of the horizontal tubing ? 150 mm ( 5,9 inch)

what do you think of this configuration ?

greetings & looking forward to read your remarks
Maarten

ps : 4 pictures attached, but it is my first post here, so i m not sure if all will go well...

I would size the batch box and chimney together; the bypass is a minor run, and not intended for full-time use.

I also think the bypass can be just a straight horizontal run from the top of the bell to the chimney, not an angled run from the riser. Riser outflow will be very hot and damage metal parts directly above it.

thank you Glenn,

i ll keep your answer in mind !

the design of the horizontal pipe can have two solutions :
1, a chimney pipe with copper windings around it, the whole inside a hollow core, made out of fire proof isolation
- no creosoot in contact with the copper
- heat transfer is not optimal, lets say minimal, maybe oil instead of water can help, but then, whats next ?
(but maybe just enough energy to heat a small water tank for showering)
- easy to maintain because out of the smoke
-> in this case i can install it underneath the riser roof, in a simple horizontal way as Glenn describes

or

2, a chimney pipe with a rvs or copper winding inside it, hollow core around it.
- creosoot ! so maintenance is necessary
- heat transfer is good
-> in this case i will need to install it on top of the roof as in my drawings, but then the question rises
? what about the metal parts because they will be exposed to a very high temperature ...
heat to water exchanger inside a chimney

looking forward to your toughts
greetz
Maarten

Hi Maarten;
Placing your copper tubing inside the riser would disrupt the flow of hot air, also  I'm afraid your copper would melt. Temps inside a riser are 1500-1800 F. possibly more with a batch box.
The other thing to note is that there is no creosote in a properly functioning RMH ,the temperatures produced, eliminate almost all particulates.
Heating water with these temperatures can lead to steam...  not good , you must avoid that at all costs. An open tank of water above that can only steam into the room rather than in a confined pipe, is acceptable.
Heating oil is a much safer medium.It does not turn to steam.  If you are only wanting warm water for washing, possibly your water can be heated by a tank of warm oil?