DSR3 build, 200mm bell system + bench

[skywalker]

We are ready to build a DS3 according to your drawings next month. System size 200 mm. Large space in a strawbale house. Let's see if that works.

Any pros and cons?

Ps: super exciting news about the test certification. 

Keep on going Peter!

[peterberg]

Wow, that's a biggie! What's the plan, this core inside a brick bell so as to create a real mass heater? That would be the first with this core incarnation, the ink of the design isn't even dry yet... I am very curious how such a scaled-up core would perform, please take the time to take pictures and videos of the build.

You might need a bypass of some sort in order to start the thing up.

[skywalker]

Feb 6, 2022 8:25:03 GMT -8 peterberg said:

Wow, that's a biggie! What's the plan, this core inside a brick bell so as to create a real mass heater? That would be the first with this core incarnation, the ink of the design isn't even dry yet... I am very curious how such a scaled-up core would perform, please take the time to take pictures and videos of the build.

You might need a bypass of some sort in order to start the thing up.

Yes the plan is to use this core within a brick bell and add a bench. Also incorporate a bypass. We will document the build and share it here on the forum. The location is perfect. A well insulated free standing strawbale house and will add a new chimney with sufficient draft. 

I'll keep you posted.

[skywalker]

Just another question peterberg:

What would you reckon would be the minimal distance between the top exit of this dsr3 core and the ceiling of the bell? I'm starting off with making some drawings for the minimum sizes this system would need. Especially the minimum total height of it is something interesting to find out in our business.

[peterberg]

In order to avoid friction: keep the space above the core equal to system size, I would say.

[skywalker]

Update: We've just finished the build of this DSR3 with a 200mm system size, bypass and open bench. All pictures off the build can be found here: drive.google.com/drive/folders/1FqSqoeGr99Cv1M45tRamwELaXmbF2oJ0?usp=sharing


In the video we've just finished the build, the stove is still wett and you will see some condense on the looking glass.

Dimensions: 

Total height 170 cm 
Width 110 cm on the front
Bench 150 cm long by 60 deep

We've used 90mm compressed earth blocks as the outer skin of the bell (oskam-vf.com/en/clay-products/compressed-earth-blocks) and halfway we've switched to a double skin bell. 40 mm earthblocks on the outside, 40 mm chamotte stones on the inside. Leaving 1 cm gap for expanding. 

There's also a bypass just below the exit port of the dsr 3 heatriser. 

We had several online meetings with peterberg discussing this build for which we are truly grateful. Thanks a lot Peter, credits for this design go to him! The design is really simple and logical and buildingwise a great improvement.

Please note that this build is still a test. We don't know yet how it's performing. 
The heater is now drying and we are planning to invite Peter to visit this stove together with his Testo equipment to run some tests and get more information on how it's performing. 

In this way we are hoping to contribute in a usefull way to this open source system and the further development. 

[martyn]

That looks fantastic and quite a bold build considering there are not any plans available!
I cant wait to see a video once you have it working on song….

[skywalker]

May 12, 2022 9:55:46 GMT -8 martyn said:

That looks fantastic and quite a bold build considering there are not any plans available!
I cant wait to see a video once you have it working on song….

Yes thats true. The client is a very good friend of us and up for an adventure. If it works than its great, otherwise we will customize it into a sidewinder batchbox or dsr2. This was a 4 day build, and we were going to do a dsr3 build research anyway.

[skywalker]

Today we've had a chance to fire it up a bit more heavy. The core of the stove is dry, but there were still some wet spots in the plaster on the outside top. This part was not yet heated sufficient because of the insulation.

We filled up the firebox for 2/3 part with just some simple pinewood leftovers.

The fire started easy, and slowly the double ram horn appaered in the top window. The top window was still black from all the litlle fires we made to help the stove dry faster but after a while the window became crystal clear.

First things we noticed:

-The stoves runs very easy
-Opening the door during the burn doesnt seem to change the behaviour. While other rocketstoves we've build have a tendency to run harder when the door is slightly opened.
-In the firebox the fire remains calm but in the topbox theres quite a turbulent fire with the tipical double ram horn.
- the ram horns remain almost till the glowing phase.

I will post videos of the burn asap.

[skywalker]

Note the soot on the looking glass and how this disappears during the burn.

[Orange]

looks great!

don't know how hot outer shell gets, I'd rather use metal than plastic mesh.

[fiedia]

I was afraid to use metal mesh inside a clay or lime plaster because of corrosion and dilatation issues. Is it stable over the years ?

I measured temperatures up to 200°C on my bell skin2 inner side. It is surprising that a plastic mesh withstands such temperatures.

[skywalker]

May 19, 2022 4:46:20 GMT -8 Orange said:

looks great!

don't know how hot outer shell gets, I'd rather use metal than plastic mesh.

The mesh is not made of solely plastic but of glassfibre with a plastic coating. It will never burn. Many years of experience on this, doesnt matter how hot the stove gets.

I'd be cautious with using iron mesh, because of expanding and rust. What's your experience on that? It seems to me iron mesh is way too sturdy too shape it around your stove in fresh plaster. 

[Orange]

I'm just cautious because of of-gassing. I've used once aluminum mesh for facade plaster, it's easy to shape.

[peterberg]

Last weekend, June 11 and 12, I went to the north of the Netherlands. In order to have a look at the build above and do a couple of testruns. This heater has been built by a collective, named 'De Vrijlemerij'. Loosely translatable as 'The Loam Freemanship', Skywalker is one of the members. This heater happened to be the first DSR3 implementation that I know of, not including my own, of course. And on top of that it's also an upscaled version, from the 130 mm (5.12") development model to a 200 mm (7.87") system.

This implementation was built during the same week that I finally managed to get the air supply right on the first prototype. Suffice to say, I was very anxious to see whether it would work the right way or not.
The builders and the owners of the heater were willing to devote most of the weekend to the test procedures. So we started with talking about how a couple of details were done. One thing that might be not that good was the extremely short chimney. Even when one took the length of the pipe inside the main bell in the equasion it was still short, something around 3 meters (9.84 ft). The standard minimum chimney length in the Netherlands is 5 meters (16.4 ft).



The heater being cold, we decided to do a warming up fire first. Mixed medium to small size of fuel, mostly beech, leaning against the rear wall of the firebox and lit on top should do the job. In fact the load could be larger but after a slow start it came upto temperature.



I was a bit puzzled by the hump of CO in the diagram between 35 and 40 minutes. But altogether it wasn't much, the flames did spin happily in the afterburner, no visible smoke out of the chimney. I walked around the house in an attempt to sniff some of the odor but all I could detect was a faint smell like a metal workshop. And oh yes, the bypass was closed at 34 minutes as is visible in the diagram.

This test was ended prematurely in order to do a refill with the biggest fuel pieces I could find. However, it seemed I delayed it too long and the pieces refused to produce long flames at first, necessary to lit the gases in the afterburner area.



Shortly after the test went well I restarted the Testo and the bypass was closed. At seven minutes the CO went through the roof, something appeared to be very wrong. Although outside there wasn't any smoke to be seen and the same faint smell of metal could be detected at the downwind side of the house. At 13 minutes the combustion seemed to be getting back to about normal. The CO level wobbled a bit, only to go through the roof again at the 21 minutes mark. Although the view through the firebox door looked quite good and still no visible smoke from the chimney at all. At the 24 minutes mark the Testo stopped, I was lucky to be able to retrieve the data from this run. The battery of the Testo ran out because I forgot to switch the external loader on. Silly enough, everything was connected and all. Maybe old age is showing up...

During the early hours of Sunday morning I suddenly realized there has been a similar experience. In Missoula Montana, during the first Innovators Event. We built the first upscaled 8" (203 mm) batchrocket using a ceramic fiber tube. The first test run showed a high level of CO which after some debate was reasoned as being the binder of the tube burning out. The Testo could detect it but mistakingly took it for CO. Which in turn would mean, for the current situation, the next test shouldn't show this behaviour anymore.

The firebox was loaded for a top-down burn, largest pieces first. Some people in the room were unsure about this approach, would those big lumps burn well? Since the whole session turned into a workshop/ lecture/ question-answer, this one could be answered as well.



The firebox wasn't really full, so top lighting could be done quite conveniently. The evening before there has been some debate about the length of the chimney. So it was lenghtened temporarily with another two meters of insulated chimney pipe. The effect was quite pronounced, a stronger draw made it necessary to alter the setting of the air inlets (air wash top and bottom) during the burn.

More about this later.