Peter van den Berg

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since May 27, 2012
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forest garden trees wofati woodworking
He's been a furniture maker, mold maker, composites specialist, quality inspector, master of boats. Roughly during the last 30 years he's been meddling with castable refractories and mass heaters. Built a dozen in different guises but never got it as far as to do it professionaly. He loves to try out new ideas, tested those by using a gas analizer.

Lived in The Hague, Netherlands all his life.
+52° 1' 47.40", +4° 22' 57.80"
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Recent posts by Peter van den Berg

I've had a look at the drawing. Do yourself a favor and raise the firebox at least 50 cm from the floor. Where is the exit hole of the bell?
3 days ago

Thomas Tipton wrote:... so while I have your attention perhaps you might indulge me on why you attempted the twin riser design.  Were you attempting to lower the riser height requirements as I am doing, or was it for another reason?  Just curiosity perhaps?

I tried to build one heater which was less deep back to front. Both risers were built exactly the same but one can't regulate uneven rising of temaperature.

Thomas Tipton wrote:Thank you again.  It's a great honor to hear from you.

1 week ago

Thomas Tipton wrote:Has anyone ever built a rocket stove with multiple risers?  And if so, what were the results?
If it failed, can you describe the failure mode.
Thank you for taking the time to read through my crazy.

Around 2009, I built a rocket stove of some sorts with twin risers. Results were meager, one of the risers tended to heat up first while the other was letting unburned gases through. There wasn't a pattern in which side heated up first, it seemed to be completely random. Escaping unburned gases means smoke for extended periods during the burn, not what we want in a properly running rocket heater.

I'd suggest you don't use a barrel but a masonry bell around the combustion core, with lots of insulation in and on the top deck. Further more, the riser could be 46" high without repercussions but there are people who did go down to 35" and still had a properly working batch box rocket. An aluminum radiation shield on spacers above the heater could further add to the safety against scorching rafters.
1 week ago

Frank Holzman wrote:This is an over complicated version of Rocket stove technology. I worked at Aprovecho in the 1980s where they developed the rocket stove. you can set one up much easier than this. I don't thin this guy really understands the principles.

Frank, I think you are mixing up the respective function of two distantly related combustion technologies.
A rocket stove to cook on is an entirely different device than a rocket mass heater to heat a house or a workshop.
1 week ago

Sidney Beauchamp wrote:Where the measurements done at the exit of the chimney or at the top of the riser ?

Neither of those. Measurements has been done in the vertical stove pipe that comes out of the heater, between 1 yard and 2 yards away from the heater's exhaust opening.

Sidney Beauchamp wrote:I have a theory that by adding a secondary vortex combustion chamber between the riser and the port, it would greatly minimize the amount of ashes that get sucked up the riser. Basically the same technology used in Dyson vacuums. It is used successfully in the Cyclone steam generators.

I am sorry, but that won't do the trick. A cyclone after the riser could be done, but it'll cost a lot of energy. Which need to be compensated by a strong draft, either from a very hot chimney or a chimney ventilator.

Sid, could you please start a separate item about your plans and proceeds? As it is now, you are going off-topic in this thread.
2 weeks ago

Sidney Beauchamp wrote:In your page you show results of measurements that demonstrates the performance of the design. I'd like to learn more about the instruments used and guidelines to run those tests so I can see the performance and share my findings.

Testing has been done with a Testo 330/2 gas analiser and a computer to log the numbers every ten seconds. Temperature, oxygen and carbonmonoxide are measured directly and can be compared with other gas analisers. All the rest is calculated  using those three, so is the efficiency. As Jura Rafal mentions, the formula to calculate that are slightly different from country to country depending on what the rules say for that specific country. So difference between mine and say, Matt Walker's analizer's efficiency is about 8%. Regrettably, making efficiency numbers a very unreliable number to go for.
2 weeks ago
The Italian version had a long time coming but it's completed now. My thanks goes to Davide Buldrini for this mammoth task he did on his own. There's no rush from the Italian people to the site yet but maybe next season?

Translation number eight is started: Russian! This one is a step up in complication as it has to be done in cyrillic lettering. Personally, I can recognize quite some percentage of French, Spanish and English of course. But Italian is out of my league and Slavic languages are way above my head. Let alone cyrillic, I can't even read the letters and what they represent!
2 weeks ago

Ashley Tarring wrote:Ive been reading a lot about batch boxes, and i keep seeing about the p-channel.
I kinda understand how it works but cant find a lot on exactly where it goes in the batch box design.
Does it enter directly into the riser or just into the steel barrel?

Neither of those, it ends inside the firebox right above the port. Most of the time a barrel isn't part of the heater's design.

Ashley Tarring wrote:And how far down should the pipe lead?

Hanging down just half an inch down the top of the port.

Ashley Tarring wrote:Also how important is it? Could you make a batch box without it?

It is important as a source of secondary air, specifically when the heater is running full tilt.
It's possible to build one without it but in that case you need to leave out the door as well. This would mean efficiency is quite a bit lower and there's also a risk of getting smoke into the room.

For comprehensive information about this and other details see
1 month ago
At the moment, there aren't any firm numbers to show. I've been in France for a one-week workshop and we've built among others also an 8" DSR. Results were mixed, the thing was prone to picking up a pulse whatever changes we made. Until... we did cut the firewood shorter so there was a space of 4" between the air inlet and the fuel. At the time the floor channel was sticking out and we used a steel angle profile to mimic a threshold and restricted the air inlet this way. At the moment we pushed back the steel angle so there was a space of 4" between it and the air inlet the pulse stopped, the exhaust cleared up and was without a discernable smell in about two minutes.

This same effect is also found in the normal batch box, sidewinder and p-channel or floor channel versions. There seems to be a need for space behind the air inlet. Also, when there's a piece of fuel sticking into the inlet the thing starts smoking just like when there's something solid in the port.

It looks like this DSR can be a viable alternative to the earlier implementations using batchrocket technology although there's a lot of more experimenting to be done.
1 month ago
May I suggest that a slanted feed tube doesn't work as well one would expect?
As drawn, all the incoming air is primary air, throttling pyrolysis of the fuel to high levels. But the combustibles produced can't be completely ingnited because there's no provision of heated secondary air. In your design there's no tunnel, the fuel is directly at the bottom of the riser and the flames are going straight up immediately. Instead of moving sideways in a horizontal tunnel which is THE essential part of the clean burning system in a rocket mass heater.
Moreover, there has been a lot of talk about metal in the core of a rocket heater, with good reason. When surrounded by high-temp resistant insulation the steel will burn away very quickly. Not by melting as such but by corroding very rapidly. By leaving out insulation the steel would probably has a better chance to survive but the so sought after clean burning is killed off too.

It's your choice to build it like this or not. But I thought I could at least warn you being on the wrong path in my opinion.
1 month ago