Heating water (--yes another thread)

[Donkey]

I was wondering when this thread would raise to the top again...

Yer answer is that it all depends. What is the context or the conditions? What is the purpose if the gizmo? And all that.
So far, my personal solutions have brought the heat to the water, AFTER the heat has dropped to a more sane temperature. My reasoning is based mostly on the surface area(and simplicity) of the various options available to me. It turns out that the water tank (even a small one) has more surface area than any reasonably sized coil that I would make. Also, coils provide more opportunity to screw up in a very dangerous way.
I'm a big proponent of passive systems, though passive systems can be VERY dangerous with solid fuels. Solids can't be regulated, and with wood in a rocket stove, they should be running at maximum hot all the time. Down in the heat riser we're seeing temperatures considerably above 1100 degrees F. which can flash water to steam instantly, which translates to "BOOM!! SQUISH!!" for you and me. Active systems meter the heat AND the speed of the water moving through and are designed with safety in mind. The water can't get explosively hot (unless something VERY wrong has happened) etc.

Everyone eventually (usually immediately) wants to heat water on their rocket stove.. It's only natural.. If you do it in an open container, then whatever, you're fine don't sweat it unless there's a coil involved somehow. If you plan to do it in a pressurized system, then you need to be VERY careful about your design.
Forgive me if you already know all this, but for me, better safe than sorry.

[bakermonitor1932]

Seams to me that a auto radiator could be used in the fire end and a custom heat exchanger in the tank place them on the same level one in the tank and one in the exhaust and rely on the natural thermosiphen to circulate the heat if the radiator burns up just find another one at the junk yard. There intended for conducting heat and have massive surface area for the fire to act on.
If more is needed use a semi radiator.

Small scale experiments could be done using cab heater cores from trucks and a 5gallon bucket.

[Donkey]

Sure. It would work fine, but improving efficiency of moving heat into water will only make the Boom!(squish) problem bigger..

I've now seen a way to do it that's totally brilliant and pretty much guarantees safety.
Check it out permaculturenews.org/2012/11/23/rocket-stove-hot-water/

[couchdiy]

I would love to heat the pool in the Spring for my aging parents. Would it be safe to use a copper coil around and above the barrel if the water is pushed through quickly by the pool filter and directly out into the pool? And does salt water make a difference?

[Donkey]

Feb 17, 2016 9:40:02 GMT -8 couchdiy said:

I would love to heat the pool in the Spring for my aging parents. Would it be safe to use a copper coil around and above the barrel if the water is pushed through quickly by the pool filter and directly out into the pool? And does salt water make a difference?

If you use large gauge pipe, like 1 inch or better for everything and follow the rules of thermosyphon to the letter, it should work fine. The limit will be how much wood you have to use and how much fiddle time would be needed for a swimming pool!! You will need a fantastic amount of BTUs to work, and wood can provide only about 6000 BTUs per pound.

[dylan]

Hello!
Canyon/Pluton 5 - i wonder how these projects are getting on did you ever get anywhere? I have a plan of my own to fire my brewery with rocket stoves. I am fairly new to it all so I was wondering if you could shed any light on any of these questions?

Here’s my rough plan:

Rocket stove water heater 1
For the initial part of the brewing process (hot water is mixed with the grains)

Design based on:
Immersion coil design (similar to this - www.permaculturenews.org/images/rocket_water_heater_diagram2.jpg)

What it needs to do:
Raise 200 Litres (42 gal) of water from ambient temperature to 78C (170F) in less than 3 hours. Water will then be used up in 2 x 100L batches.

Questions:
Will the water ever get that hot in this type of design?
Is it the most efficient way of heating lots of water?
I imagine this is scaleable (as long as temps are reached) whilst the fire burns, and the tap is running?


Rocket Stove Water Heater 2
To boil the beer.

Design based on:
Institutional barrel stove - www.youtube.com/watch?v=VdhLWMW7IXA

What it needs to do:
Boil 160L (42gal) of beer rigorously for 1 hour.

Questions:
Is this the best design for this?
Is there a limit to how big this design can get? (i realise i would have to make my own drums etc, i.e not a 55gal drum)
What if I wanted to boil 400L (105 gal) of water?


Thanks to all in advance!

D