Hello! This is my first completed stove.

[Forsythe]

I love this so much! sertus , you rock!!

I'm so happy to see that front slot (above the firebox) working for your secondary air intake! I've been playing around with very similar side-slots brought up along the left and right of the firebox, which then feed into the port from the sides in a very similar manner... But your idea here for feeding secondary air directly from the front might work even better... since the secondary air would have less residence time to superheat and over-expand... which ultimately lowers the amount of oxygen reaching the port. (Peter had recently come to this conclusion with his bottom-up air feed — which had a greater pre-heating residence time before entering the burn chamber.) donkey32.proboards.com/post/37584/thread

It seems crazy that preheated secondary air would actually be capable of overheating and thus over-expanding... but the concept holds true for wood-fired kilns, too, and it has always amazed me in that context as well: It's easier to fire a kiln in the dead of winter or in the cool of night —when the air supply is cold or cool— because the amount of available oxygen in *cold* air is greater per volumetric unit of air... simply because cold air is so much more dense than hot air.

Supposedly, this holds especially true for kilns at high elevations, where air is less-dense by virtue of lower atmospheric pressure at high altitude... and so bringing cold air into the kiln firebox improves combustion efficiency, by ensuring the fire has enough O2 for complete burn of the pyrolizing wood gasses. That's just... mindblowingly counter-intuitive.


Above all, thank you for sharing all these results, videos, and sketches, Sertus! Your contributions here are outstanding, and very much appreciated — Cheers!

[sertus]

Hello, Forsythe ! Thanks for the good review! I follow and read your forum posts that educate me and challenge me to look for problems and find solutions in my theoretical and practical developments and experiments! Following the guidance that peterberg has shared and continues to share, in future builds I will increase the gap between the hearth and the secondary chamber so that it feeds secondary air through the 20% CSA.

"It seems crazy that preheated secondary air would actually be capable of overheating and thus over-expanding... but the concept holds true for wood-fired kilns, too, and it has always amazed me in that context as well: It's easier to fire a kiln in the dead of winter or in the cool of night —when the air supply is cold or cool— because the amount of available oxygen in *cold* air is greater per volumetric unit of air... simply because cold air is so much more dense than hot air."

I can call the stove whose pictures I have posted "idiot-proof" because I loaded it in all possible ways in order to destroy it from high temperature or to get smoke out of the short 1.5 m chimney. The samples were at an external temperature of ~ 35 degrees Celsius. While I was shooting, I got so hot that I had to go out in the sun to cool down. After the initial fuming for ~10 min during which the system heats up, no smoke is released when adding fairly thick wood on top of the coarse red coals, when adding 0.5~1kg wood chips, when adding small pieces of bicycle tire. After I convinced myself of the so-called "idiot-proof", I disassembled the stove and built it at the address where it will be used - sealed, with an isolated hearth and a bypass for easier starting. The truth will emerge with the first autumn frosts.

[hof]

Good stove!

[sertus]

Thank you, hof!

[sertus]

Photos and videos from October 30 - what the hearth and afterburner chamber of the stove look like from the inside, the device, the charging, the ignition and the burning process of the stove.Timing and some temperatures.
youtu.be/gKQdl_yH_Ck

[Vortex]

Hi Stefan, That looks great!
It's a nice clean burn up to about the 8 minute mark on the video, then she starts over-fueling. The vortex should stay in the afterburner (second floor), otherwise the carbon monoxide will be really high. It looks like it's happening because you're lighting the fire from the bottom, that causes too much wood-gas to be released to quickly from the heating of all the wood above. Try a top lit fire with the logs horizontally laid front to back, biggest at the bottom getting smaller up to the kindling at the top.

Trev

[sertus]

Hi Trev! In principle, you are absolutely right! I would use similar words after seeing the video file! I made the following mistakes when loading, igniting and during combustion:
1. The geometry, parameters, proven by experiments and logic demanded that I load the hearth relatively densely, without worries, because the previous (in the summer) ignitions showed calm, without overloading, burns. However, I allowed and loaded the stove "loosely", not taking advantage of its full potential. I lit it in the top third, but the looseness allowed the fire to go down too quickly.
2. During the burning, shortly after the stove ignited, about 7 minutes, through the opening for primary air, which is located on the hearth door, I pushed the heated logs. As a result, I got a super flare and a quick, sharp increase in pyrolysis - the secondary combustion chamber choked, but I want to note that she did not vomit . So the burn turned into a sprint to the finish. To be honest, I'm glad the stove did the trick, swallowed the big bite and snuggled up for about 2 hours.
Trev, I designed the stove to be loaded with wood in a vertical position - no room for a stove with logs stacked horizontally. I don't want to describe my emotions when I received the ordered wood, for the stove in question - normal one-third of one meter - about 33 cm, I sized the hearth according to the logic that a normal person cuts a cube of wood consisting of one-meter pieces. Here is the place of:
3. The loading timbers range from 18 to 24, 26, 28, 30cm. This forces me to put a horizontal first row to put on the vertical logs and fill the intended volume of wood to the intended height - distance to the port of the secondary chamber.
4. My desire to do a perfect and real/original photo shoot of the stove failed me. The previous day (29.10) I loaded and ignited according to the rules provided by me for this stove quantity, volume, density and height of logs of wood. I achieved the normal beautiful, calm, clean burn lasting about three hours. THE PRE-PREMIER AT WHICH I DIDN'T HAVE A LASER THERMOMETER!
5. I did NOT have time to do another perfect third photo shoot the next day. MEA CULPA!!!

I have an idea how to avoid overloading with a design change, but I'll do my secret experiments first . I think #martyn, as a fan of fire paintings, will love it!
Be inspired and thank you for all you have shared and "fired" me on the idea of ​​"what is and what can be" the wood stove!

[solobird]

Hi Stefan, nice heater, thanks for sharing!
Could you tell us a few words about the materials used for the build (firebox/bell).
Also is the bell just a hollow chamber or does it have any interior walls ? What's it's ISA ? I see you're getting good temps on your exhaust - 80C.

[sertus]

Hello #solobird ! Thanks for the kind words!

For the hearth, I have used refractory plates 300 x 240 x 30 mm. On the outside, it is insulated with fire-resistant wool 25 mm - 1260 0C.

The first, second and third floors of the chamber for secondary combustion are in a common volume (box), made of insulating plate 25 mm - 1260 0C. The formation of the flue gas path in the first and second floor is by means of cordierite furnace shelves. From the same shelves, I have also formed the space between the hearth and the chamber for secondary combustion - this is the path of the secondary air.

The bell is built of 40 mm thick refractory concrete slabs cast by me - 1350 0C.

The stove has a "second skin" - for additional heat accumulation + aesthetic considerations, I used 330 x 330 mm terracotta (granite).

My calculations are based on a system size 110mm. I don't know how much they correspond to the "canon", but the stove works and heats better than expected .

[solobird]

The insulating plate for the box is 1260C CFB (ceramic fiber board), right ?
I'm asking because from what i've read the recommended ISA for the standard batch rocket for a 150mm system is 5.3 m2 while for the same size DSR3 it's 3.3 m2 (as per scalable dsr3 specs).
A very good core inside a very efficient convective system getting most out of the fuel. Glad it's working fine for you!

[sertus]

Right. Ceramic refractory plates for high temperatures. They are made of aluminosilicate fibers and have a temperature class of 1260 oC. At the moment, the internal surface of the heat exchanger (bell) is 1.6 square meters. I am thinking of increasing the surface to 2.2 square meters for the next heating season.