first test fire in DSR3 core

[iau461]

Today was the first test burn of our 8" DSR3 core. It went well enough that I don't think we need another test, and will soon start to build it in place with its bell and bench.

Video is here, along with a couple pics of my cast afterburner and forms:

photos.app.goo.gl/VqjiHKNUafJUYqvXA

Conditions today were:
- about 81 degrees F and humid - not ideal for getting a draft going. :-)
- no rain or wind - yay!
- firebox filled about 1/2 full with wood that was still a bit wet; threw in some dry 2x4 after about 25 minutes

Things I think I learned:

1) Simonds Heatguard Refractory Coating (similar to Satanite, ITC-100, etc.) does not form a hard surface when dry. More like a powder layer that bound to my refractory castings OK, but did not bind AT ALL to super-duty hard firebrick, or to slate. I'll find out tomorrow, when we disassemble the core, whether it stayed bound to the surface of my cast afterburner, which is the most important place. I had hoped to coat the entire inside of the firebox, but that would be pointless because it is so easily brushed off. Oh, and by the way, if you buy the Simonds stuff, ignore the directed mix/water ratio, it is WILDLY off. Instead, look at YouTube videos on how to achieve a "sour cream" consistency.

2) Don't use slate anywhere. At least not if it isn't well dried. I thought maybe I could get away with it on the bottom of the firebox, with a coating of the Simonds. Nope. Slate cracked in multiple places. No problem, that's why we do tests! :-)

3) It burned fine with the "doors" open, but there was usually a bit of smoke and hot gas coming out of the front of the firebox. I imagine that will be eliminated by an actual door, with intake ports of approximately system size?

4) Overall, I'm happy. I don't have a Testo, but the exhaust gas was completely clear about half the time, and only slightly smoky otherwise. I imagine this will only get better with a full load of drier wood.

Thanks to all who helped me get this far. More comments and suggestions welcome.

[martyn]

Twin chimneys are unusual.

[peterberg]

Congrats with a successful build of this rare core!

3) It burned fine with the "doors" open, but there was usually a bit of smoke and hot gas coming out of the front of the firebox. I imagine that will be eliminated by an actual door, with intake ports of approximately system size?

Yes, the door with an appopriate airframe will take care of the little puffs of smoke. The real test is when the heater is installed of course, stick to the proportions and so on and you will be fine.

[iau461]

Aug 26, 2023 4:31:05 GMT -8 martyn said:

Twin chimneys are unusual.

At the time, it seemed like the easiest way to create a test chimney of approximately the right system size. Two 6" risers being about 12% larger in area than a single 8" riser. Easy to buy the parts at the big box store. And I will reuse the 6" duct in the bench area. No intention to have a double chimney in the final build. :-)

[iau461]

Aug 26, 2023 7:02:34 GMT -8 peterberg said:

Congrats with a successful build of this rare core!

3) It burned fine with the "doors" open, but there was usually a bit of smoke and hot gas coming out of the front of the firebox. I imagine that will be eliminated by an actual door, with intake ports of approximately system size?

Yes, the door with an appopriate airframe will take care of the little puffs of smoke. The real test is when the heater is installed of course, stick to the proportions and so on and you will be fine.

Thanks, I obviously couldn't have done it without you!



Will definitely be sticking to the proportions. ISA of the bell is undersized, but I'm planning to actively heat a very large bench whenever the exhaust temps get high enough. Hoping this will allow me to "fine tune" the heat capture vs. exhaust/waste.

Going to replace the slate floor with cheap hard brick.

If anyone has a recommendation on material for the bell ceiling I am all ears. Mine will be about 36x60", with no penetrations. I have a good supply of superwool for lining the bell sides, and top if needed.

[iau461]

Hi mrkelley,

Peter van den Berg's work on the DSR3 starting in early 2021 is recorded here:

donkey32.proboards.com/thread/3710/dsr1-vortex-aspects-dsr3?page=7

In this post on the Permies site

permies.com/t/40/192518/Planning-DSR-Build-Cooktop-Questions

April Wickes posted this spreadsheet 10 months ago, after extensive discussions with Peter van den Berg on DSR3 specs:

docs.google.com/spreadsheets/d/1NtSG8JYFwjceHdosV2u81YJz48gw78qr8_DaigujjMo/edit#gid=1527349678

And here's a link to the SketchUp file for my build, based on that spreadsheet:

app.sketchup.com/share/tc/northAmerica/VU0EoNURxl0?stoken=FzGlRSPGWB6imlpYQsPRxaXTNi_uh9qUun8uVrVMfyspdjKQTgFyDodLSY7BM0nu&source=web

Good luck!

[foxtatic]

Aug 26, 2023 9:40:49 GMT -8 iau461 said:

If anyone has a recommendation on material for the bell ceiling I am all ears. Mine will be about 36x60", with no penetrations.

 Working on my own DSR3 build currently. How is yours going, one year later? 

I've been looking into all the bell top options. Kiln shelf is too expensive (and wouldn't work for your 36 inch span.) Cast refractory is also surprisingly expensive and costs out even higher than kiln shelf from my calculations. Vermiculite board would also be too small for your span. And those are about the only options aside from the good old fashioned method of making rails out of angle iron back-to-back hold spans of fire brick. Which is what I'm opting to do after exhausting the other options!