My outdoor water heater RMH project

So I found out about rocket heaters a couple days ago and this evening I set up a cinder block rocket heater with about $17 worth of materials from a home store. It lit and took off surprisingly well and got me really excited to build a real mass heater that I hope to eventually heat my home and outbuilding with. I am currently using pellets in the garage and propane in the house and it would be nice to eliminate most of the cost of both if possible. I still need to figure out my wood supply better but there are many sources including a neighboring woods that I may be able to get permission to "maintain".

I saw a couple of water heater designs but I like the idea of the RMH's I see Ernie and Erica building with the 55 gallon drum for radiant and the bed of mass with horizontal exhaust. My book hasn't come yet but I can see the reasoning behind it all. The idea would be to make this into a pallet mounted module in a framework, sheet metal sides with insulation (much like you see those kentucky wood gobbler type yard mounted wood boilers). This would have the same layout except around the drum would be some kind heat exchangers to absorb the radiant heat from the drum (but not overboard as to kill combustion temp) and then the exhaust pipe would stay horizontal and be submerged in the waterbath. Most of it would be metal to contain the water but whatever areas need to be masonry would be masonry. It would be an open to air system so no steam involved.

It would be cool to see if it can be run in the summer for hot water and run a stirling engine pto to do some kind of air conditioning:)

I have the skills to do the job, just need the time and patience to find materials cheap instead of buying out of convenience. I have had this project in the back of my mind for 7 years now but didn't have a clean hot cheap fuel source like these rmh designs.

Right now I just want to blow the heat off in each building with a radiator and eventually make a coil for the home's hot water heater.

Going to be fun building this, anyone have any links to similar builds or ideas for me?

Progress so far, Decided to try as best I can to burn wood chips with a gravity feed system. I left the front of the burn chamber unfinished as I am going to be trying a few designs to get them to burn. Will be sending about 18 feet of 6" mechanical tubing through the barrels to try to transfer as much heat from the flue as possible. Right now I have the riser and burn chamber mortared, ran out of clay to make clay slip for the perlite mix that insulates between the heat riser liner and the outer shell. Warming up to 39F tomorrow so hoping to be able to get some clay dug up and thawed out so I can keep going.

Nice job, and nice shop...
I'm working with interchangeble feeds too.
Are the "exhaust" barrels for water heating, or set up as bells?
Kudos from balmy Milwaukee!

Andor

You live all the way over there in Milwaukee?

Yep, I am sending 6" pipe from the barrel through the horizontal barrels, back through and out a third time for a total of 18' flue. Heating 110 gallons of water (minus the exhaust volume). If that proves to be too small of volume I was going to add some more water storage but only time will tell.

Beautiful work. I also agree with "beautiful shop". I'd like to know how many bricks you used and were they refractory (fire bricks)? Did you bond them with thin-set or fire-brick mortar?
I am particularly impressed with using that double walled stack for the chimney. I have a 6" stack and will probably do the same thng.

I was going to ask how you were going to move that thing from the garage to another location but then I did see the wheels on the bottom of the two girders.

Any idea what that thing will weigh with water in "both barels"? The other question I was going to ask is how did you cut the top off the jacket for the chimney. You see it in the early photo with the top on and then in subsequent photo you see it with the top cut off. Are you using a plasma cutter or a saw of some sort? I've been using hacksaw blades made for my jig saw which really work well. I do use my sawzall on some things because of the angles, though.

I used to live in Milwaukee, but now am out in the wilds so heat for the living space and hot water are certainly near the very top of the list for creature comfort/survival above the 45th parallel.
Nice work!!!

Thanks, I think i have 24 full fire bricks and a sheet of 10 half bricks for the floor. I used alsey airset fireplace mortar http://alsey.com/products/residential-mortar-indoor/ and Alsey firebrick available from County materials in Pewaukee.

To do it over again I would probably ditch the triple wall stainless pipe and go with a firebrick riser. Every thing I hear is that metal of almost every variety will degrade in the heat riser eventually. I'll cross that bridge when I get there but if I was starting from scratch I would just brick the chamber and riser as one and then continue like I have it there with that nice stainless drum. That piece couldn't have been more perfect for the job.

I have another big batch of clay slip to make for filling the insulation in around the barrel and then I am going to work on the outlet transition into the other drums.

I made the transition out of the barrel last night and hung a crappy piece of 6" duct I had laying around for a makeshift exhaust. Set some block around the front and lit it with my propane torch, viola. It's putting out copious amounts of steam, roasting the water out of my clay/perlite insulation. It has a way to go before it's done but the first lighting is kind of fun (and anti-climactic).

...moving forward in WI...
next time you might wanna check out Firebrick Engineers here in Milwaukee, or I might be able to deliver - I have family in Manitowoc...

andor

Hi John,
Im Just outside of Hayward. I have not built one of these yet. But I have been trying to do my research first. I wonder if all the square corners were cut out,would it inprove the air flow in and out. For example the attachement you added for exhaust on the barrel is great compared to most pictures of other projects I have seen. I was wondering if it had a curved flange inside to get air flowing more direct out of the barrel and less turbulance. Just a thought. Like thinking of how a Head Match to Intake on a small block chevy works so much better than stock. We remove all rough corners to improve air flow.

Great Pictures and Nice Clean project you have going here.
Good Luck

Thank you Andor, If/when I do another one I will look you up, they sound like specialists in the field. I was thinking after incorporating this stainless burn tube how the next one would be all firebrick instead with just a metal insulation barrel.

Whipped together a quickie feed tube, 4" diameter, and managed to burn about a 3 foot column of wood chips. Like my brush I was burning yesterday it was wet and took some doing to get it going, but still managed to burn it. Found some better looking woodchips today hoping to try again tomorrow. I'm just trying to get the moisture baked out of the bottom layer of perlite/slip insulation but haven't been able to get this thing really roaring yet just playing around. May just have to get it going with regular dry wood sticks instead so I can get the moisture out and some paint baked off. I'll post the video of it running when I get a chance.

John,
...always good to have a bag of wood pellets to play with, <$4 for 40# bag of dry fuel @ Menards
my trick with wood chips here in the city: find them free at parks and municipal depots, sieve out the fines for my worm bin
- dry and save the rest for later use, a few bucketfuls can go a long way in testing, especially if they chipped a dead standing, leafless oak or ash!
remember the second hand stores for cheap stainless steel mugs, colanders etc for making perforated screens - see other"pellet" posts

Andor, Burning pellets in the garage right now, have 20 bags I could play with. Going to try a batch of wood chips I dried last night and see if they burn any better. Have plenty of pellets so when i want to get it roaring I'll probably whip up a feeder for those and see how it does. Found a perforated metal bin at the junkyard that is a perfect screen for the burner. Was trying to get a feel for these wood chips and the thing I am concluding is that wet is no good regardless of how dead. I burned th other chips last night and they seemed to burn a little better (larger chunk) but they are probably still too wet to be effective fuel. The plan is to find an arborist or two and wait all summer for the perfect load(s), like you say, an ideal dry dead hardwood tree they are shredding, shouldn't be too hard to find. They say they would give them away free if the drive isn't too far. Right now I am burning stuff I have found at the time, probably wet brush type chips.

Haven't been able to post in two weeks, had a crash, rmh fell off the dolly and shifted everything, very disheartening. Patched it back up, should work just fine. Brought it inside to try to use heat from the barrel now that I have the riser somewhat dried out. Making a makeshift flue and will have it running indoors this week, will put up some photos and video as soon as time allows.

when working with water it is best not to expose more things to leakage than necessary. The best way to heat water using rmh or any other heat sources is to run copper tubing around the heat source to extract the heat.

Nice job with the build. Love your enthusiasm

Yes indeed, Thank you. I will be putting coils on the top and side of the main drum as need be, trying to figure out the burn chamber first to see where I want to rob heat from, don't want to cool it down too much and inhibit the quality of the burn.