andrew stevens

any suggestions what sort of insulation / material i should consider for insulating the water tank ?

cutting out the top of the rocket stove barrel ( and maybe reinforcing the bottom of the water barrel with some thick steel ) a good idea

as is using an L-shaped flue instead of J-shaped, so heat from the coals will contribute to warming the water

very glad i sought some feedback here : )

here are some updated renders of the evolving design ; )

i don't mind at all if it takes 2 hours or whatever to heat the water : ) the point is to do it in an anti-fragile way that doesn't rely complicated devices or fuel externalities beyond my control

this is def gonna happen in whatever final form the design takes

i will absolutely document the process and post the results here as documentation / discussion fodder for anyone else thinking similarly to reference 🤝

this is a good point, though i don't think 55 gallons would be quite enough for the envisioned use. do you think the rocket stove steel drum would potentially support the weight of 2 drums welded together for the water tank ?

good tip on the shutoff valve to the solar collector loop as well 🫡

( understood mod requests to delete posts should go in this sub-topic )

if possible can we delete this thread :

https://permies.com/t/362863/combination-passive-solar-collector-rocket

i posted it to the "plumbing" board but really it should have gone in the "rocket mass heaters" board

since i've now replicated it at RMH and the original post in plumbing as yet has no replies wanna avoid avoid duplication

sorry for the trouble and thanks ! 🙏

looking to get some feedback on a combo solar / wood fired water heater design

this will go into a straw bale house at 8000' in southern colorado, design priority places an emphasis on anti-fragility

primary heating element : a passive solar heat collector using a thermosiphon glycol loop copper tubing heat exchanger inside the water tank, preferably WITHOUT a pump involved. would also like to have the ability to further heat the water using an integrated rocket stove, for cloudy days or occasions when more hot water or hotter water are desired

- will commission a welder build / modify a custom water tank that allows the upper end of the rocket stove barrel to to nest under it for conduction heating
- solar loop in / out connects to a large passive solar water heater on the outside of the south-facing wall

have seen quite a lot of rocket stove water heater vids on youtube but most of those are using copper tubing to make a heat exchange loop around the rocket stove interior J-flue. have not seen anyone attempt to nest the barrel under a water tank for direct heating via conduction, which seems like a simpler approach. can't imagine why it wouldn't work ?

( see attached illustrations )

some considerations :

- water tank will obviously need an aperture at the top to prevent pressure build-up
- this system is envisioned as very hands-on / monitored while heating using the stove - if temp gets too high / water boils solution is to let the rocket stove fire die and manually add more water from the well inlet
- rocket stove exhaust outlet run under a short ( likely cob ) bench and up through the roof
- weight of water tank is supported on ring stand with legs / rocket stove bears no weight
- water tank will be well insulated

- servicing the interior of the rocket stove barrel will prove challenging in this setup. if the j-shaped chimney inside it built of high quality refractory bricks how likely / often would one expect this to pose an issue ?

purpose of this water heater : provide hot water to the kitchen sink, bathroom sink, and a small soaking tub

- soaking tub will be insulated and exposed to incoming sunlight on the south side, so it should be possible to get the water in there lukewarm by end of day before adding any solar / wood heated water to bring it up to soaking temperature

- daily use will require filling the water tank in the morning so the solar collector can heat the water and using the soaking tub in the evening

anything i'm missing / misconstruing / missed opportunities before i attempt this ?

thanks for your time and attention ! 🙏