Satamax Antone wrote:So Brian, any update on this one?
Unfortunately I’ve moved to New England and I’m not currently involved in any rocket heater builds. But “Uncle Mud” Chris McClellen actually installed this particular build in his home.
He sent me an update about the installation in early December:
“Your double shoebox is a lovely addition to our home. It does smoke when you are feeding it and not as clean/stingy as a regular rocket but REALLY great to watch the flames on and a nice long burn with the flooring cutoffs we use.”
If he’s around the Permies forum, maybe he can stop in and comment further, but I’m not sure how to “ping” him to this comment.
Thomas Tipton wrote:I was interested in hearing more about an 8" riser.
Unfortunately the original company mentioned in this post went out of business. The company that bought them out would make an 8” riser if requested but there would be a $1000 mold fee up front, so unless a lot of people organized a group buy for 8” risers it would be cost prohibitive.
My apologies, folks. I just took down the eBay ads for my shippable cores because my hands are going to be full for the coming months. (I’m the primary care taker for my 82 yo mom, and she just had massive emergency cardiac surgery, so I expect to be preoccupied for the foreseeable future.)
If you’re still interested in obtaining one of the 6” BBR shippable cores and not in a hurry, get in touch with me here via private message and I’ll still make them available that way. I just can’t fulfill any eBay orders in a timely manner for the foreseeable future.
Test fit, temporary while I make measurements for the masonry benches. Hearth is 96” wide, and now 27” deep since I extended it. The wood stove is 24” wide, 17” tall. The square metal box on top of it is 24”x24”x14” tall. Benches will be blind ended and 24”x24”, with 2’ bench to the right of the rocket and 4’ to the left. The metal box on top will have a 4”x6” mica glass viewport into the DSR above the firebox, with a view into the area above the port.
I have a 14 gauge sheet metal square box that’s 24”x24”x14” tall that’s going to sit above this. It has a 6” round flue collar on the bottom rear of the box that I’m going to use as a bypass with a blast gate. Since the wood stove is only 17” deep, there will be a 7”x24” space at the rear for the exhaust to pass into two blind masonry benches. One of those benches will contain this Conservo Toledo Cooker as a white oven. The whole assembly will sit on a 10” hearth in front of a fireplace so a chimney won’t be very difficult.
The firebox is now complete, along with the Double Shoebox Riser (DSR) on top, and the secondary air tube and flange are now mounted. The holes in the wood stove frame under the door were widened to provide increased secondary air area.
Next: Finish the firebox, the double shoe box riser (DSR), build the benches using reclaimed old 18”x9”x4.5” firebrick and 2’x2’ cement sidewalk pavers, figure out how to integrate this Conservo Toledo Cooker as a white oven, cap the rocket primary bell with a 14g square 24”x24”x 14” sheet metal box maintaining enough breathing space between the DSR and the cap, and apply a blast gate as a bypass damper on the bottom rear of the 24”x24” metal box cap...
Just to be clear, you can’t use just any old wood stove for these purposes. It needs to be a lighter gauge plate steel body (not cast iron) for ease of modification while maintaining structural integrity, and the size and shape of both the firebox and door have to both be easily modified and incorporated into the rocket heater build. Plus if it was mass produced for a long time at an inexpensive price point when new, it’s often cheaper on the used market. Doors with glass are a bonus; double doors or doors that are too wide or tall or have an odd mechanism for closing or latching should be avoided.
Frankly, I’ve searched literally thousands of Craigslist ads from several states here in northeastern USA, and the only unit I’ve found so far that meets all these criteria is the Vogelzang Frontiersman. I suspect that an Englander NC13 ( maybe the NC30) would also work, but I haven’t seen one in person yet. I’m sure there are others but I haven’t found them yet.
So far I’ve found three of these particular stoves on Craigslist. I picked up the first two for $45 each, and the third for $150 last week. But it came with 10’ of class A stainless steel chimney including a complete through the roof assembly, and I sold that tonight on Craigslist for $125. So for a net investment of $115 I’ve gotten 3 full wood stoves to modify - $38 each.
How to make a BBR rocket masonry heater firebox frame out of an old wood stove
Today I started modifying a Vogelzang Frontiersman wood stove I found on Craigslist for $45. I simply used a Harbor Freight 7” angle grinder ($45 with coupon) and Metabo cutting disks to modify it.
First I removed all the firebricks lining the wood stove and cut out the top, then the angle iron on the insides of the left, right and rear wood stove walls that previously held the firebricks in place.
I’m left with an empty 21” wide x 17.5” deep by 15” tall rectangular steel box that I can use to hold my 6” or 8” rocket core. (I’ll add a photo from a recent 8” masonry rocket heater build that utilized one of these wood stoves, but the core was in a traditional front to rear, left sidewinder orientation. I had to add door glass to the firebox door.)
This took less than an hour of light work yesterday afternoon. In this build, I’m going to use a 6” BBR core oriented from left to right, with the firebox door being part of the right hand wall of the firebox. Port will be in the ceiling of the firebox on the far right, with a double shoebox riser directly above the firebox.
A 24”x24”x14” deep square 14g steel box will sit directly over the wood stove with double shoe box firebox and riser, and that will sit between 2 masonry benches on my family room fireplace hearth.
But I just wanted to show how easy and cheap it can be to use old plate steel wood stoves like the Frontiersman to solve the issue of how to “build and mount” a firebox door with glass window.
I’m using one of my 6” shippable cores (with minor modifications) to build this firebox and double shoebox riser configuration, and I’ll add pictures as that takes shape. The primary air holes already in the firebox door will be modified for primary air. The holes under the door in the wood stove frame will be modified and used to introduce the secondary air through the recess in the 1” ceramic fiber board under the firebrick split floor of the firebox. (The two current air holes currently seen in the rear wall of the wood stove will be sealed off by the left side wall of the firebox.)
Adam Jonathan wrote:Does anyone sell a door for an 8" batch rocket with a window in it?
I don't know how to weld, and don't have equipment.
I'm thinking of hiring someone, but it would be easier just to buy a door and a p-trap, I think.
Keep an eye out on Craigslist for an older Vogelzang Frontiersman wood stove. They were an inexpensive plate steel wood stove with a cast iron door and usually had a window. I’ve found three of them now, two for $45 and one for $150.
They’re not hard to modify and use as a frame around a batch box rocket core. I’ve used one for an 8” masonry rocket build and I’m sketching plans using one for a 6” build.
I’m no expert on eBay but it sounds like you need to create a new account with the Montana address associated with it so eBay will allow you to make a purchase. We do not ship outside the continental US at this point so it sounds like their software is kicking out your current account due to the address currently associated with it.
We will not be making a one piece vacuum formed ceramic fiber mold as a core unless there is demand for one because of the high initial molding and tooling costs. Unless there is a demand for quite a few of these the molding costs would make the price per unit too high. We do not offer any refractory castings for the firebox.
C Jones wrote:This is wonderful, so glad someone is doing this. And that you've gotten to the actual sales stage! Congrats!
Can you give a real quick (like, three or four sentences maybe) intro to the level of work required to turn one of your kits into an actual functional heater (mass or not)? I'm trying to gauge the feasibility. Does one have to have studied the books, know some special skills, have nine strong friends, etc. etc. etc.
Also, how much does the kit weigh....would one able-bodied person be able to wrangle it inside from delivery by themselves?
This kit is just the firebox core and expansion chamber/riser. There's no door, barrel or masonry tower, exhaust manifold, bench or bell, flue, etc. Its still going to take a decent knowledge base of rocket heater basics to turn take this core and then build the rest of a functioning batch box riser rocket heater around it. But this core contains the hardest to source refractory parts for the firebox core and riser, in easy to assemble large pieces (eliminates most of the masonry joint work) , so it should make the rest of the build relatively easy.
The kit is between 60 and 70lbs, and comes in one 24"x16"x16" heavy duty cardboard box. If its too heavy to manage, you can just open it up where UPS left it and carry the pieces individually. The heaviest pieces are the two 21"x9" pieces of 2600HS IFB, but they're only about 12lbs a piece. Handle everything with care as both IFB and ceramic fiber board are relatively easy to break.
If you signified which rocket configuration you desired at time of purchase, left or right sidewinder or rear port, the Venturi port will already be cut in the firebox walls. If not, pre-set the parts of the firebox walls, figure out where you'll be placing the port, then follow Peter van den Berg's instructions for a 6" rocket heater at http://batchrocket.eu/en/building#dimension to cut the port in the IFB firebox walls. IFB can be drilled easily for pilot holes for the port and cut easily with a hacksaw blade, other hand saw, band saw or jig saw.
The parts go together pretty easily like a sheet cake on the bottom. First, one piece of 21" long sheet metal with a 1" lip at the sides and 3" at the rear. Next, 1" ceramic fiber board with the cut out up the middle for a secondary air channel is set flat inside the sheet metal, using the lips as a guide. Then assemble the stainless steel flange to the second, 20.5" piece of sheet metal using the mounting holes provided. Place this metal sheet directly on top of the 1" ceramic fiber board, with 1/2" space to the front edge of the 1" ceramic fiber board. This metal sheet has upward facing 1" lips on the sides, no rear lip, and an upward facing 3 1/4" lip as a sill in the front. Assemble the round stainless steel tube flush in the flange, and tighten the 2.5mm Allan wrench set screw.
Next walls are assembled. Using 3000 degree refractory mortar (supplied) put a thin coat on the bottom edge and left and right edges of the 13.5"x9" IFB rear wall, and place it firmly with a 9" side facing down, centered against the rear lip of the sheet metal, with a 2.5" space on the left and the right side for the side walls.
Left and right walls are next. Put mortar on the bottom of the 21"x9" pieces of IFB and firmly set them in place on the left and right sides, using the left, right and rear lips of the sheet metal as a guide. Now do the same with the two 21"x4.5" pieces of IFB,making sure they contact the rear walls. GENTLY tap all the walls together and downward (a rubber matter helps) to seat them firmly in place.
If you signified which configuration, left or right sidewinder or rear port as well as horizontal or vertical riser orientation (only with sidewinders), the 6" exhaust hole will already be cut in the ceramic fiber board for the expansion chamber/riser. If not, set up the expansion chamber/riser first, figure out where you want to place your 6" exhaust hole, make a pilot hole with a drill bit, and cut it out with a hack saw (blade only), drywall saw or jig saw.
Next take the ceramic cement (supplied) and apply to the top edges of the left, right, and rear firebox walls. Place the 20.5"x14" piece of 2" which ceramic board firmly on top of the firewalls. Place some weight centered over the rear, left and right walls of the firebox (a line of firebrick or two stacked red bricks should be sufficient) and let it all set up for at least 12 hours. Next set the four 2" expansion chamber walls upright in a 14"x16.5" rectangle. Apply the ceramic cement to the opposing surfaces of the walls and press firmly together, then apply ceramic cement to the top of the 4 walls and firmly press the 14"x16'.5" piece if 1" ceramic fiber board on top of the ceramic fiber rectangle walls. Place some weight (a line of firebrick or two stacked red bricks should be sufficient) centered over the 4 walls and let it set up for at least 12 hours.
After the firebox and the expansion chamber/riser have been allowed to set, place the expansion chamber in the left or right sidewinder horizontal or vertical orientation, or vertical orientation for the rear port configuration. Apply ceramic cement to the surfaces which will contact the firebox, then press them together firmly, using weight to hold them in position while they set for another 12 hours. Be very careful in removing the weights before building the remainder of the rocket heater so as not to cause them to separate.
Ceramic cement will be supplied in a ziplock bag approximately the consistency of runny peanut butter or thick pancake batter, and will be applied with a cake icing bag and nozzle (supplied.)
Refractory mortar will also be supplied in a ziplock bag and can be applied with a small trowel (or a big kitchen spatula, as long as your spouse never finds out ;-)
(I just typed up instructions from the top of my head, and don't have photos to illustrate them yet, so please let me know if they're not clear.)
There are few commercially available rocket heaters in the USA:
1) Dragon Heaters
2) Zaug Stoves
3) Liberator Rocket
Regarding all three options, these only represent the rocket heater itself, not the ‘mass’ (cob or masonry bench or “bell”) necessary for the rocket heater to heat up and which releases heat long after the rocket heater fire has gone out. The latter two are also all metal designs, and among the rocket heater community a common saying is “metal is doomed” due to spalling of the metal in the high temps developed in a properly insulated rocket heater core (2100-2200•F.)
Also, these represent “J” tube configurations, which are being eclipsed by “batch box” designs (with a small traditional firebox and door) which can be seen at Batchrocket.eu - Introduction and in most of Matt Walker’s designs
A clean out T with a removable cap placed in the chimney pipe can solve smokeback as related above. Mount a small metal cup on the inside of the cap and replace the cap while burning a fire starter in the cup prior to lighting the rocket. This will heat the chimney and establish draft. No reliance on electricity.
It does work. I have one on my back yard rocket and I’ve done start ups in cold rainy weather with and without it. With it there is NO smoke back. Without it, in cold rainy weather, smoke back conditions sometimes persisted 10-15 minutes.
I was visiting my local metal shop today, and I told him I need a cheap 100% effective bypass draft control for 6" stove pipe. He recommended I try a blast gate. They're "used to open and close branch ducts in a dust extraction vacuum system allowing air to be diverted only to machines that are operating, thus conserving air volume."
Its actually cast aluminum with a sliding galvanized steel blade with a locking screw. Since it will be open on start up, he didn't think the galvanized metal would be a problem and when its closed its out of the direct exhaust flow. I can dissemble it and easily replace the blade with heavier gauge stainless if necessary. Its also relatively light and fits inside 6" stove pipe well. A 6" is ~$15. They make sizes from 2” up to 24”.
Logan Keister wrote:
All things considered, if the shipping were to land somewhere in the $100 - $150 range, $500 +/- total is something I could certainly live with. I like the idea of starting to mess with RMH's in my spare time, but my current situation is as such that I may be better just buying the core and starting there rather than trying to learn from scratch. I bought the book from Ernie and Erica W. not all that long ago, but haven't had time yet to read it. Still trying to navigate my way through my day job, school, and being a newlywed, all the while living in an old farmhouse (that conveniently had frozen water lines to the kitchen sink yesterday). Can't wait to see the site when it's done, I have it pinned as a favorite! Merry Christmas and Happy New Years to you as well!
Actually, I'm pretty happy with where this shippable core kit ended up as far as a reasonable price. If I had pursued a vacuum formed ceramic fiber shape lined with dense fire brick splits as a core it would have cost $500 to $600 a piece, and I really thought that would have been too much. I can still go that route as another option in the future if there's demand for it.
Logan Keister wrote:I'll admit, I've been stalking this thread as a guest to the permies forum up until about a week ago, when I got my account. Did you ever decide on a price for these kits?
I'll be honest, between the 8 days I spent in NC with the rocket heater builds there and other travel this month, I've just gotten around to a detailed cost analysis in the last couple days. Because of the price of these big blocks, and using the more expensive 2600degree HS (High strength) insulating fire brick ("IFB") plus the high cost of ceramic fiber insulation board, plus my time to pick them up at the factory two hours away and to hand make each of these, the introductory price for a 6" batch box left or right sidewinder port or rear port design, with a simple ceramic board box expansion chamber/riser that will work with any of these configurations, will be $349 plus shipping. (This ceramic board expansion chamber/ riser can either be used horizontally or vertically, is about 8" deep and the length and width of the fire box.)
The kit will be easily assembled by the purchaser. The side bricks will be assembled and attached to the floor with 3000degree refractory mortar (supplied) and the roof of the firebox as well as the expansion chamber/riser walls and roof will be assembled with ceramic cement (also supplied.)
I still have to package a shippable core kit and take it to UPS to get a weight and typical shipping prices.
An 8" shippable core will be available February 1, 2017. It will cost more in proportion to the much larger firebox.
A 6" double shoe box configuration will be available in the coming months as the results come in on the design. That configuration is still experimental.
I'l also make whole individual 2300degree IFB 24"x9"x2.5" or 3" (for traditional vertical risers) and 2600HS 24"x9"x2.5" IFB slabs, as well as individual sheets of different thicknesses of ceramic fiber board available, as well as the stainless steel secondary air flanges and tubes, in the near future.
(I'm still working on the website with my web designer and we still hope to have a basic website and eBay store online January1, 2018, but that depends on his availability over these holidays, so it could be delayed a week or two.)
Merry Christmas and Happy New Years!
The shippable core will be similar to the fire box below, with 2600HS IFB sides and 1" ceramic fiber board roof, a 1" ceramic fiber board floor with a secondary air recess between two sheet metal plates, but with a short stainless steel secondary air delivery tube like in the second photo. The purchaser will need to line the firebox floor, either with flat dense firebrick splits, or with angled dense fire bricks like in PvdB's illustrations:
“On another note - the statistics of this bell heater are going to knock some socks off. I only have to burn maybe 1 full load in a day, maybe 2 arm loads, keeps the whole place toasty - wonder what insulation can do? haha.”
There must be 4000-5000lbs of mass in the masonry of this stove, and that’s the key distinction when people who have them claim they only use a fraction of the Firewood they would have burned in a regular wood stove. They capture, hold then slowly release massive numbers of BTUs. I don’t even think my Woodstock soapstone Ideal Steel Stove (an incredibly clean burning hybrid modern wood stove) could have compared to the effect this mass has on gleaning every ounce of heat out of the exhaust stream.
The homeowner was heating a HUGE interior space because the house was literally built like a modern barn, and only a third of it was finished and insulated, the third where we built this massive masonry rocket stove. So while this masonry rocket heater was performing exceptionally well, all the heat was flowing out into the main part of the structure and straight up the large third floor cupola, and he was having trouble keeping the temp up in the finished/insulated part of the structure.
Since I left, I recommended he build a wall with French doors at the end of the finished/insulated space to separate it from the rest of the structure and keep the heat in the finished area from the masonry rocket heater. He has almost completed the wall, and is thrilled with the results, as the first floor is staying really toasty, and the heat from the masonry rocket rises up the stairwell in the finished area and is keeping the second floor of the finished area really warm as well.
I can put one of these together for you fairly easily if it would suit your needs (but I need to order some parts first.) It’s a full size 6” batch box rocket heater only, no mass, using PvdB’s new double shoe box design. Im not sure about shipping to Canada though. It’s fairly light weight, less than 120 pounds.
And here’s the 6” rocket self contained in one 55 gallon barrel I just completed for him. It uses Peter’s new double shoebox (top port) design, a firebox door designed for Ugly Drum Smokers, a USSC 6” flue collar, and a clean out T in the 6” flue to use to warm up the chimney and prevent smoke back by inserting a small fire starter (or in this case we just used heavy brown paper from the refractory mortar bags.)
The firebox of both these stoves utilize a shippable core with 2600• HS (High Strenth) large insulating fire bricks for the walls and 1” ceramic fiber board for the roof. The 8” system is a tradional left sidewinder with 60” vertical riser made of 2300• regular insulating firebrick. The shoebox on top of the 6” firebox utilizes 2” ceramic fiber board for the walls and 1” for the top.
The barrel got to 800 degrees tonight but I still need to drill some air inlets in the firebox door frame.
Joseph Crawley (Asheville NC) and his friend Caleb, a mason, joined me for a team effort to help a gentleman in North Carolina this week build both an 8” masonry rocket mass heater with blind benches and a 6” rocket heater self contained in one barrel (plus a 11” pedestal/manifold.) We started Monday morning and had the first fires in both units tonight.
I ended up using the larger SS auto exhaust tube that Matt Walker had recommended. It’s about 2 1/8” diameter. (It’s hard to tell here but it is up against the rear wall of the port.) I also made the port depth 2 1/2”.
Peter van den Berg wrote:I don't know where you saw the square tube, I used several rectangle ducts at home, the best results were obtained with 60x40x2mm (2.36" x 1.57" x 0.08") and 2.25" x 1.5" in Montana. I'm not that sure about the latter one, maybe it happened to be slightly larger. The tubing I've been using was roughly 1.7 times larger compared to yours. The double shoebox air inlet openings are nearly 1:1, primary and secondary. It's quite different from the straight batch box or the sidewinder.
I must have been thinking of your earlier standard secondary air supply tube?
Regardless, I have a 3” SS exhaust pipe that Matt Walker had recommended recently. I can easily convert to that if this size is insufficient. What would be signs of starving for secondary air?
Peter van den Berg wrote:The tube should be dead against the back wall and as such is at the back of the port. The thickness of the firebox ceiling is in your proposal 2.5", as is the port depth. I'd recommend the stainless tube to end about halfway in the depth of the port, it's now 0.5" below. So it should be just 1.5" higher than it is at the moment.
I tried several configurations but this one seems to yield the best results and is the simplest at the same time. What's the diameter of that SS duct? It looks a bit small compared to what I used at home and in Montana.
Great, thanks again Peter! I have enough adjust-ability the way I made it to do both of those fairly easily.
The secondary air passage under the firebrick is 2"x1" and the SS secondary air delivery tube is 1.67" diameter. Since you had been using 1 1/4" square tube I felt that should be adequate?