I posted a year or so back about my project to develop a truly engineered Rocket Stove (see previous thread showing early prototype - https://permies.com/t/59117/adjustable-wood-pellet-rocket-stove ). My design is modular and allows the heater to be used for a variety of purposes- Hot tub heater, sauna heater, space heater and pizza oven. The unit can, if the user wishes, be vented through Mass just like any other RMS (unless being run with the water heater attachment). It has been engineered to last and so uses high-end materials such as refractory, ceramic fibre, vermiculite board and 316 stainless.
It has now gone through 3 prototypes and has been heating our hot tub for over a year. 1000litres of water from tap cold to 100F in 3 hours using 20lbs of wood pellets.
In space heater mode, I have measured the top of space heater barrel at 1100F, but it has a cruising heat of 752F. This is outside of the top of barrel- inside the core would be far hotter.
It is mainly designed to run on sustainable wood pellets. Here in the UK, we can buy these easily at $4 a 20lbs bag. However, it will have adaptors to allow wood chips, charcoal and wood to be used. The great advantage of the wood pellets is that a hopper can be filled (included in base unit) and the heater will run indefinitely (we have often let it run for 8hrs without any fire tending etc. )
I am currently going through the process of protecting aspects of my design with patents - primarily the adjustable heat control (range 400F-1100F with no loss of efficiency) and the water heating aspect. The design also utilizes a unique burn tunnel shape that I may also protect.
What I would love is some feedback from the community as to interest in this design. The unit is modular- so you buy the base unit and then add the capability as and when you need it. i.e you could buy the base unit with the space heater attachment and then at a later date add the water heating attachment. You then can change them over as your usage dictates.
I would love feedback on the expected retail price:
Base unit- $1950
Space heater hood (with ceramic glass viewing window) - $650