Rocket mass heater for a large warehouse?

I'm interested in building a rocket mass heater for my 5000 sq foot, poorly-insulated warehouse. Is that crazy? Will it do any good? We currently have 4 enormous natural gas space-heaters on the ceiling which make it quite toasty, but I'd love to reduce the use of them and also try out building an RMH before I make one for my home. Can I put it straight onto the concrete floor? There's an old furnace chimney in the center of the building no longer in use; I might be able to vent through that. Anybody have any brilliant input on this? Thanks!!

go for it! Any heat put in by the rmh should offset the cost to heat with your other furnace. A warehouse version could be pretty cheap and crude and still get the job done.

if the concrete isn't insulated from the ground, you'll lose a whole lot of heat downward where it won't do you much good. insulating the mass from the concrete would mitigate that problem.

. There's à few who've asked before, and i'm in the same boat kind of. I want to heat my future workshop with one.

First of all i would use an horizontal feed batch rocket myself.

Or may be a huge J tube. At Donkey's board, there was à guy talking about something similar. Making a 20"x20" in J tube of 250kw. http://donkey32.proboards.com/index.cgi?board=discuss&action=display&thread=640

I'm doing woodwork mainly. And having a J tube rocket, buried in the slab, with the mouth flush with it would be nice, as i could sweep the dust and offcuts straight into it.

For the bell, (barrel) i think using an old heating oil tank, or may be a big propane one. If you don't want to go that big, air compressor tanks or hot water tank could do it. I have an horizontal feed batch rocket into a 500l hot water tank.

And, it's a shame that your slab is most certainly not insulated, otherwise, you could have cut chanels for the flue pipes in it, then laid the pîpes and re poured concrete on top. You could always do this, digging a hole in your slab, insulating the bottom and sides with four inch styrofoam, bring it up 1 or 2 inch shy of the surface, put your pipes in it with checking T or whatever. Then pour concrete back in. Should be prety easy if you have a massonry saw and à mini digger. I'd say 2 cubic metres if you don't burry the rocket in it, 3 if you do (cubic metre or cubic yard is aproximately the same.)

Hth.

Max.

or start your build with a sheet of some kind of insulation and when you move out you could bust up the heater and haul it out in pieces if you ever want it gone (or it doesn't end up working to your satisfaction).

Oh, good point about the concrete floor not being insulated; I'm sure it's not. But it's not my building, so I can't cut a hole in the floor. Maybe I could build up an insulated base. Any suggestions on what would work best? Also on specifics of the stove itself? I see the plans for sale in these forums, two sets of them, marked 8" and 6", but I'm totally new to this and don't even know to what those measurements refer, much less which one I should choose.

Actually, would anyone out there be interested in coming to lead a workshop to build this thing? I'm quite willing to dive in and try it on my own, but I'd be far happier to have some guidance. As I said, I'm totally new to RMHs in particular, and building anything like this in general. The fanciest tool I own is a handheld drill, and all the technical spec talk in the forums is totally over my head.

If you get a friend who is mechanically inclined to help I bet you could make it happen. Having a large open space gives you lots of options that people trying to squeeze something like this into their homes don't have. I am thinking if you found a large long well built pallet you could use that as your base and work from there. Think a really large 8" scale version of something like this:

Download the pdf of the book here and you should have 75% of the info you need http://www.rocketstoves.com/

So the Ianto Evans book is the way to go, not the Erica/Ernie plans?

I saw that video and was thinking something like that. But what keeps the wood from catching fire? Can I build a sturdy insulated wood platform and then cover it with cob and surround it with a cob bench with the flue running through it? I'm envisioning a bench that wraps around the stove rather than sticking out away from it, just to use the space better.

A handy friend... I'll see what I can round up. One of my employees is good at that sort of thing; I'll ask him. I was just kind of hoping to find someone who had actually built an RMH before.

Gryphon, check this http://donkey32.proboards.com/index.cgi?board=experiment&action=display&thread=511

They last a smidge more on their wood.

Gryphon Corpus wrote:So the Ianto Evans book is the way to go, not the Erica/Ernie plans?

I saw that video and was thinking something like that. But what keeps the wood from catching fire? Can I build a sturdy insulated wood platform and then cover it with cob and surround it with a cob bench with the flue running through it? I'm envisioning a bench that wraps around the stove rather than sticking out away from it, just to use the space better.

A handy friend... I'll see what I can round up. One of my employees is good at that sort of thing; I'll ask him. I was just kind of hoping to find someone who had actually built an RMH before.

Erica and Ernie's plans might be helpful but the book is usually the first place to start for something like this. When designing the flue you want to keep in consideration that you would have to clean this thing every once in a while and the more complicated you make the exhaust the trickier it's going to be to get in there. If you want to use a vertical stack chimney it sounds like you will need some extra heat left in the exhaust to get the gases to rise. Ideally a hole in the wall would be the best exhaust, but if you are renting it might not be an option for you.

Keep in mind I haven't actually built a successful unit, just a test rocket to play around with the concept. Mine is in the garage half built right now but I have spent more time researching this than I care to admit so i have come across most of the common questions and have formed my own opinions of what I would do if I were in a certain situation. In your business do you have to worry about fire inspectors or insurance issues? These are the main reasons I am locating mine outside and going hydronic.

Book downloaded.

That makes sense that one as to be able to get into it, and to have enough heat to drive it up the chimney. I don't think my landlord would care for me punching a huge hole in the wall, especially when there's a great big chimney in the middle of the building already. But it does go up a good 15-17 feet, if not more. Will that be a problem? Will I lose too much of my heat up the chimney? And how does one make a pipe inside a cob bench accessible, even if it's straight?

The fire inspector has never been by, so I'm not worried about that. Our insurance guy probably won't love it, but he's also pretty relaxed and has never inspected anything. We have massive open flames all the time anyway.

Satamax Antone wrote:Gryphon, check this http://donkey32.proboards.com/index.cgi?board=experiment&action=display&thread=511

They last a smidge more on their wood.

Thanks, I'll read through it! So much information out there; it's all a little overwhelming at this point.

Gryphon Corpus wrote:Book downloaded.

That makes sense that one as to be able to get into it, and to have enough heat to drive it up the chimney. I don't think my landlord would care for me punching a huge hole in the wall, especially when there's a great big chimney in the middle of the building already. But it does go up a good 15-17 feet, if not more. Will that be a problem? Will I lose too much of my heat up the chimney? And how does one make a pipe inside a cob bench accessible, even if it's straight?

You could replace a window with a board and a hole cut in it if that's an option, chimney would lose some heat but I have no idea how much or how much it would effect the rocket-y-ness. A chimney adds one more dimension to cleaning and also needs to be properly sized for the system, may limit how big you can go. At this point I would think you could make this thing big and pour some heat out of it. As for the mass, cob=work to me so I would be thinking along the lines of loose mass that can be delivered by truck for cheap and it would keep labor down, pea gravel for instance. I would like to think you could do this whole thing hand mixing little or no actual cob but maybe a slurry in a batch mixer and dumping it in... Others on this board would know more on the best mass to use for a job like this, there is kind of a theory to it I am sure.

To clean the flues you can run a t with a cap on the end and leave the cap accessible on the outside of the box.

So much to think about! Window-hole is not an option - we only have overhead glass doors and just got brand new ones today (yay!!), so no cutting holes in those. I'll have to investigate the chimney - it used to have a great big boiler attached to it, so it's huge, with just a big round hole in the side to attach the pipe.

I like the idea of not mixing a ton of cob! Pea gravel with a slurry? What kind of slurry? And in what would the pea gravel contained?

Erica would be the best to ask about different mass materials, I was just speculating as it sounds like you are in an industrialized area and not necessarily a homesteader working with the native materials readily available. Either way it sounds like you don't want air trapped in your mass as it will act as an insulator (they were saying even sand has some insulation value as there are little pockets of air between the grains). Heck you might even be able to just get bag mix concrete at the home store and rent a portable cement mixer but again I have very minimal experience in this area to know why that would be a bad idea. This thread has a great post by Erica about mixing cob: https://permies.com/t/18864/stoves/thermal-mass-materials

Just like that video you could build a box to contain everything, could build forklift clearance under the bottom so it could be moved if need be.

Ill be watching this thread. Can you post a picture of the space/warehouse?

Any one that has tinkered or built one has good info. I will say though, Ernie's been my biggest motivator.

Ooh, very helpful bit in Erica's post at the end about reducing the weight of the bench - after I figure out this RMH in my studio, I want to build another for my house, which has wood joist floors.

I'll get a photo of the space where I want to put the stove in the studio, maybe later today.

Okay, here are photos of the chimney inside and out, and the little cleaning flap at the bottom. My landlord says I can just attach the exit duct to that hole in the chimney, which is 8" in diameter.

Sorry for the sideways photo; here it is turned.

totally doable. might need to rearrange some clutter, though...

That's not clutter, that's very high-end luxury yarn! But yes, it's moveable