Dan (brother) is still working on a foam grinder for me.  He’s not working so it might catch his attention a little more often and I might actually have something to play with by late spring.  As soon as I can grind some foam I’ll get the eps-crete infill installed in the north wall of the sun porch.  Once that’s done I can pour the last bit of footer and get the east wall glass put in.  Once that’s done I can get my fish tank moved in and my aquaponic grow wall (lettuce, tomatoes, peppers, et al grown in hydroton) put in place and start growing for our table.  Right now the fish tank is outside half sunk into the ground.  I can’t grow anything attached to it until the weather warms fairly dramatically unless I install a heater in the tank.  I can’t do that until I get the new electric service in (coming up soon!).  Getting the tank into the enclosed sun porch will greatly lengthen the growing season without increasing the electric bill.

It’s been so warm I haven’t been able to talk Wadly into installing the sawdust stove.  I keep hearing “next winter” when I mention it.  I know better than to push.  He pays the electric bill and collects the sawdust we’ll burn once the burner’s installed, so it’s best for me to just go with the flow.  When he’s ready, we’ll get it installed.  I’ll start pushing him mid to late summer so it’s done when the cold weather hits.

Wadly’s planning to burn the paint off so it’s safe to light indoors.

You might want to check this out.  A person commenting on a previous post turned me onto a forum thread about a sawdust stove being used in a wood shop.  Thanks Nancy.

In future I hope to have dry hardwood sawdust to burn.  Keeping us supplied is going to be Wadly’s job.  Right now we have two stove loads of cedar sawdust.  That will do to get us started, but it won’t last beyond a day or two.

Note to self; learn how to braze and find your your anvil.

Raw sheet metal parts.

I took my concept for the bottom workings of the sawdust stove to our local sheet metal shop and they did a brilliant job of turning my concept into solid objects.  All this perfection (not the vent adapter which I got at Goodwill for $5) cost $89.  That’s a heck of a deal, in my mind.  I just don’t have the tools to easily cut and bend metal.

Yesterday I cut the hole for the sleeve/drawer in the 55 gallon drum.  The hole looks great.  It’s a tiny bit smaller than the final, but I’ll leave it as is until I talk to Lorr.  I’m dealing with a barrel that has a fairly good arch in the bottom, so want to have flexibility for which way I jump when putting this all together.

The hole in the sleeve (piece standing on end) has had its edges bent upward to facilitate centering and supporting the burn chamber.

All these bits (not the vent adapter) are to be tack welded Saturday at Lorr’s.  I’ll try and get good pics of the assembly process.

I haven’t cut the exhaust hole yet.  I don’t want to do that until I talk to Lorr.  He may not be okay with using the vent adapter.  Cutting the hole to match the vent adapter reduces my ability to step back and punt.

I see two benefits and one drawback to using a water heater tank.  Benefit: it’s a smaller diameter which will allow me to consider an insulating sleeve around the outside of the burn tank.  Benefit: the top of the water tank is domed.  Used top down as the burn tank, it will facilitate the removal of ash.  Drawback: the tank is smaller in diameter so will burn for a shorter period of time.

I’ve been pondering the sawdust stove and how/why it works.  When first lit, the sawdust stove emulates a rocket stove.  The burn tank circumference is insulated by the compacted sawdust.  As the sawdust is consumed the stack reduces in height and the room at the top of the burn chamber becomes as a secondary burn area for flue gasses.  I’m dying to know if insulating the burn chamber sides will improve performance.  It is probably totally unnecessary as the sawdust stove is noted for its complete burn of the fuel.

I can’t wait to start experimenting.

The premise of the sawdust burner is to use a low/no cost waste material to supply heat in a stove that can be hand built quickly, easily and inexpensively.  The plus for me is I can disassemble the stove and cart it outside for the summer months.  A 30 gallon barrel of sawdust should burn for about 8 hours.  With extra 30 gallon barrels pre-filled with sawdust I can quickly replace a spent barrel with a fully stocked one as needed and filling the barrels outside would keep a good part of the mess out of the house.

In one of my forays on the web I ran across a video of a sawdust burning heater built in England.  You can watch the video here.  The model in the video is available from British Hardwoods Online for about $500 US.  Shipping inside England is about $75 US.  In an attempt to get a real clear idea how the stove was built, I did some searching and, through chance, ran across an old open source plan for a “double-drum sawdust stove“.  The plans are available (free) online at VITA.  Do a search for double-drum sawdust stove and you should find the link.

The design shown in the video is a takeoff (improvement) of the original double-drum sawdust stove design. When comparing the plans to the video, take special note of the difference in location of the single exhaust exit from the outside barrel near the bottom, the lack of damper on the chimney (not needed or advised) and legs instead of a “false floor” in the outside barrel. The inside barrel’s three legs hold it above the ash drawer and allows air to circulate around inside the bottom of the outside barrel facilitating the exhaust up the chimney.

These relatively simple changes improve the performance of the design over the original.  With parts and self-labor, this stove, with the aforementioned design changes, can be built for about $100 US.  As we build I’ll keep close account of what we spend as opposed to what we can salvage so I can share the result at the end.

Wadly is embracing the task of accumulating the necessary 55 gallon and 30 gallon drums.  I will acquire the stove pipe, sheet metal, metal drawer pulls, adhesive and gasket material.  In addition I’ll need to buy a 45° and two 90° elbows.

Rather than weld legs on the barrels, I’m going to use three fire bricks to hold the inside barrel off the bottom of the outside drum.  I’ll buy (hopefully used) stainless drawer pulls for the handles on the lid and drawer.  If I can’t find the pulls I want I’ll build some out of 3/8 mild steel rod.  I’ll fold, spindle and mutilate a piece of sheet metal for the drawer and I’ll use the cut-out piece as part of the vent control on the drawer face. I’m a bit fuzzy on this part, but I’ll get there.

I want to be able to install temporary fire proof wall covers for the corner where the burner will rest.  I’ve got plenty of fire brick to make a base on which to set the burner.  I can mortar them in with a clay/sand mortar which will make them easy to take apart and clean for reuse or I can build a 2×4 fence and set them in place therein.

I’ll supply pics as we build/test/build/test so you can see what works and what doesn’t.

RMH with permit - installed in the Dana Annex

One of the points of discussion at the rocket mass heater workshop was how to get RMHs permitted by local government.  RMHs aren’t a wood stove, they aren’t a masonry stove and unless you’re a RMH aficionado, which city and county permitting departments generally aren’t, getting a permit to get one built and approved is a fairly steep road.

Ernie Wisner and Erica Ritter have been working toward getting the basic RMH tested and approved.  They were able to get a permit for the RMH installation in the Dana Annex but the county/city hasn’t yet signed off on it.

To get the rocket mass heater design approved, emissions need to be certified by an accredited lab.  With the stove technology certified, the permitting process for all of us becomes much easier.  We need to get this technology transitioned from *experimental* to tested, something all of us who want to install a RMH need.

Toward that end, I have seeded a fund for testing and certifying the rocket mass heater but funding the project is something I can’t do this alone.  I need your help.  If you are an alternative building person, you understand how important it is to get the technology we advocate recognized and approved.  It’s we, the little people, who are going to make this happen.  If you think RMHs are fascinating, contribute and be part of the development of this technology.

If you can squeeze some money out for this project, be assured it will be used wisely.  Donations earmarked for Testing Fees will be used specifically for the costs associated with certification using an EPA-certified lab or university.  Certification gets us a big step toward an accepted permitting process.

Donations specified for use in general research will be used for the purchase of refractory materials, water-heating parts and other materials needed to develop test builds.  This is research from which we will all benefit.

PayPal your donation to eawisner@gmail.com.  When you donate, designate whether you want your funds to be used for RESEARCH or TESTING FEES.  Please help me support this worthy project.

I’m planning a 7″ system because I’m planning to use 8″x6″ rectangular steel tubing for my riser.  That cross sectional area translates closest to 7″ round pipe.  Because I have to have some of the thermal mass inside and some in the sun porch, I will have to calculate my turns carefully to ensure I don’t add so much equivalent length I slow the flow excessively.

The mock-up of my stove encourages me to find a larger diameter riser.  The 6″ well casing I have will work, but bigger in my case may be the difference between marginally functional and awesomely functional.  Ernie’s suggesting an 8″ core and I’m agreeing . . . bigger in this case is better as long as I don’t go above 8″.

I put a “want” out for 8″ well casing on our local freecycle and our County’s 2Good2Toss.  I’m not really expecting any results but I have to try.  I probably shouldn’t be fussing about this as the installation isn’t going to be a long term one.  I could use 8″ stove pipe.  It’s certainly more readily available, would easily last the couple years I need it to and I know where the scrap pile is for our local stove store.  But you know me, I’ve always got to say “what if”.

Logging is big in our area.  Short lengths of log truck reach (3/16″ thick 8″x6″ tubing) are pretty readily available.  With Wadly’s connections I could probably score 50+ inches of that fairly easily.  So the question is, can I use 8″x6″ steel tubing for the riser?  What effect will the rectangular shape have on the draw/draft?  I’ve posted queries on the RMH Experimenter’s Corner and and on the Permies Alternative Energy forum.  I won’t hold my breath waiting for answers.

Riser in place and base for barrel in the works

Working through the exhaust port detail

Mocked up exhaust port

Making sure the barrel is properly supported

With barrel added and fire started

Nice clean burn, good draft

Without an insulated riser, once the barrel warmed up, draft was lost and smoke-back was unfixable

Knocked apart when the test was over

Last weekend I attended a rocket mass heater workshop put on by Ernie Wisner and Erica Ritter.  I learned SO much!  You cannot imagine!  I’m going to try and cover a very small portion of what I learned.

I learned I will not be able to use all the lovely free stainless steel ducting in the construction of my rocket mass heater.  Some I will re-purpose to improve air circulation between rooms.  Whatever I have left won’t go to waste.  You know me, I’ll find a use for it.

I spent the night at Ernie and Erica’s on the RMH bench in their living room.  My hips loved the heat.

My RMH requirements are a bit out of the norm, so I took my parts with me to do a bit of testing to see where I would have issues.  The whole process was extremely educational.  The pics on the left are thumbnails.  You’ll need to click the thumbnail to see the detail.

In addition to the four paying attendees was an awesome and ever changing group of young people known collectively as “the legs”.  You will see bits of them in the photos of my rocket mass heater test.

I’ll post more later.