barrel business

[Prescott]

Howdy Gang!

Dialing in measurements and materials (I may have, after finally abandoning all hope, landed a local source of gray river clay ) and interesting in some barrel perspective...

I am casting an insulated core and heat riser. The latter being 14" at it's widest (filled with all sorts of insulation due to creating a 6" system) and rethinking the 50 gallon barrel. It's just HUGE, and the 32 gallon barrel really fits my space so much more naturally.

So the details and questions that arise are thus:

The 50 gallon barrel will yield a 4 1/2 in gap all the way around the heat riser.

The 32 (it might be 30, to me what matters are the measurements...) gallon barrel will yield a 2" gap around the heat riser.

I am running less than 20 feet of pipe in my bench, with three elbows going into a sound/solid/reliable chimney inside the living space, the first four straight feet of pipe is a highly insulated water heating element right after the plenum and first clean out then elbow. I am more interested in the heat getting to the water heater (in an open system, no BOOM+SQUISH here) and bench than the barrel, and know that insulating the barrel is a no-no...

What are the advantages, disadvantages, pros and cons of the barrel sizes for this system?

With my (rather busy winter) work schedule I am looking at only a couple of hours of burning about 14 hours apart.

I am willing to take the pains to make the smaller barrel fit uniformly over the heat riser if it will be enough cooling, pumping and pulling.

Thanks for having a look and weighing in! I'll be casting the core in a couple weeks and will soon be creating a thread to document the process. The latter only being fair, as I have learned so much from others doing so, and hoping to hear from the like!

Rocket on~p

[mannytheseacow]

I don't know about the barrel size, but on another note- I've been doing some tinkering and I think if I had to do it all over again I would abandon the idea of a square burn tunnel and feed and just use a 6" pipe as a form all the way through the core. I think you're guaranteed to keep a consistent size and nice burn all the way through. Especially since you're joining back to a round riser anyway. In the big picture I don't know how much it matters, but if you're starting from scratch that's the way I'd go. Sorry, I know this doesn't answer your question at all. Good luck with your build. I'm excited to see how it turns out. Especially the water heating part!

[matt walker]

Prescott, I tend to think that most of the idea of one or the other fitting better in your space is mostly an illusion since the 55 looks so much bigger than a 30. In reality, in the space, the difference between the 22.5" and 18.5" diameters is not probably going to change much about the way you use your space.

That said, there's no reason at all you can't try the 30 and see how it works for you. You can, and will, temporarily seal the bottom with a little bit of cob during the course of your build. It will be a matter of a couple minutes to try out both and see what you prefer. I tend to think that you will end up with the 55, but maybe not. Those 30 gallon barrels can be tough to find, I've got one on deck in my garage right now, but they only come around every so often.

Manny, as for the round vs. square, I do think it would work fine round. There is some evidence that the right angle at the back/top of the tunnel makes a long rotor into the riser, helping mixing a lot. If it were round in section that would only be a very small section. On the other hand, perhaps the flow would be better. I do think that once we are at this level of insulation, the finer points of the shapes are a matter of single digit efficiency changes in the burn and are unlikely to be able to be discerned by us. So yeah, if it's easier to build, I bet it's great.

[DevilsBrew]

As an amateur, I've never understood the whole square riser bit. If you are creating a vortex, it only seems reasonable that a cylinder would be ideal. The function of a rocket stove is to manipulate gas. Having or not having a physical structure will change the pressure and energy. But then, I am only in the bleachers.

[Prescott]

Sometimes threads steer in different directions...

I see why many make square cores, especially when working with bricks etc. materials often play a significant role. I mean look at the Dragon Burner heat riser, talk about low tech/no tech! I am not being negative, it is functional and simple (note to self, that's a good thing!) and their burner is remarkable! And mostly square...

I am going with square personally, as I am constructing the core's core out of wood I can manipulate. I will be notching the outside of the mould for tripwires (top and sides just bast the feed tube) and then a little swoop in the back bottom corner of the burn chamber, and adding that little "horn" above the swoop for turbulence in the HR. (details from the donkeyboards and the development of the dragon core)

All that said, I then shift to round for the HR because, you guessed it, materials! A round barrel for the outside and sonotube for the inside.

Back on topic, Matt I like your approach. I do have both barrels and though it doesn't sound like a big difference, when mocked up its noticeable. The 55 has a removable top and the key factor for me, oodles of room for the plenum, which is a metal wall vent 4x12 1/2. It is near (but not dangerously close) a window on the north side of the house and blocks some precious light, but the heat and comfort it will generate will trump those little details...

Thanks for the feedback y'all. I pick up my fire clay in a week and if I can prep enough this week, will cast the core with my (6year old) son!