thomas rubino

Hi Tess, Welcome to Permies.
I do not know if it is cold where you live, but even if not, be sure to go check out the Rocket Mass Heater forum. Really cool stuff.

Hi, Von, Welcome to Permies!
To start a new thread, choose your forum (Rocket Mass Heaters) and click New Topic.

Name your thread appropriately, perhaps "Help with new Batchbox."
Tell us about your location, what temperatures are expected, and the size of the area you are trying to heat.
What kind of building are you wanting to heat?
This will keep all replies on your topic.
With the information we currently have, I can tell you that not many spaces require an eight-inch Batchbox.

Hi Ben;
Nice little rocket-style stove you built there.
Building rockets with glass has been tried before.  They are beautiful while burning, and as a rocket stove, they work great.
Other than the high costs of fire glass (average $10 a square inch), and the constant danger of the glass getting broken while a fire is burning.
As a mass heater, ultimately, you will not be happy.
The problem is that a lot of heat is escaping through the glass.
Here's what will happen if you try to turn that into a mass heater.
To start, as soon as you divert the exhaust from leaving straight up from the riser, your glass will blacken, and you will still see flames, but not the way you're hoping.
Next, because heat is escaping the core and not all of it is going through the riser, you will not reach the high temperatures required for a full burn.
You'll create ash build-up, and the infamous creosote will form, creating a chimney fire in the making.

If you want glass, consider building a proven Shorty Core; she can have a nice, large window to enjoy the fire.
Also, there are the double shoebox designs (DSR) that offer a spectacular view of the double ram's horn fire in the upper box.
Rocket scientist Fox James has some great videos of these designs.

Hey Josh.
I forgot about the "Baffle", leave that out, and please don't put any restrictions in the chimney system of an RMH.
Next, regarding AI, Liz has found it extremely useful for her business. However, she is asking for keywords or descriptions for artistic work.
In this case, you are asking it to make mechanical suggestions on a subject with significant conflicting information, due to ongoing innovation.
Ask at Permies, Donkeys pro boards, Walker stoves, Peter Berg himself, even Dragontech will help answer questions.
Call me old-fashioned, but I don't believe AI is as qualified as the folks who developed these stoves.

Yes Josh;
A 33" burn tunnel is much to long.
That makes the roof of your burn tunnel 17" long.
Glenn has 8=9", I prefer 10", but have found 12" to work, but no more than that.

Your buddy is asking that slowed down 8" J to push through 6" pipes, again, not to specifications.
A recipe for an ash-plugged system.
I used a 2.5" gap on my 8" for seven years.
I also had a 48" riser. I recorded a 1100°F reading on an 8" glowing red circle on my barrel top.
The riser can be within an inch of the barrel on one side.
What kind of transition area is the barrel dumping into?

You asked why a long burn tunnel is bad.
To create the temperatures at which J-Tubes are recorded.
You must allow the gases free easy movement, although it looks like your J-Tube is burning properly, I assure you it is not.
The core portion of any RMH must be built to specifications if you expect it to work like we say it does.

In your example, the gases are slowed by their horizontal travel. When they reach the riser, they cannot get the 1800°F temperature that it is touted to reach.
This allows Ash to reach the transition area and enter the pipe system.
Increasing the riser height to compensate does not solve the problem.
After the riser, he is asking for 8" of hot gas to travel through a 6" pipe.
It fills with Ash, slowing it down to the point it will not light properly anymore.
I know this to be a fact, as my 15" burn tunnel roof, plugged with ash by mid-winter...
Prior to that, I thought I had a Bad Ass Rip Roaring J-Tube...  I did not.

I believe it needs a rebuild to "factory" specifications, if he wants factory high-performance results.

Hi Cerbu;
Those are wood gases burning, but the source of the colors is a mystery to me.

Hi Matthias;
I agree with Ben, you need a matching chimney, perhaps even a 150mm for your 5.1" Shorty.
I have both a Shorty and several 1st-generation Batchboxes.
Shorty is an incredible stove, but she does not have the power of a first-gen.
As casual as Shorty burns, she "might" flow with a smaller flue, but there is a much better chance she will not like it.
Peter has recommended the use of a bypass with Shorty, something he did  not recommend with his other designs.

You could try if you wish, but I would have a larger pipe on hand; I think you will need it.
Perhaps Peter will give us his opinion.

Josh;
You mentioned that the burn tunnel was made longer than it was supposed to be.
How long is it?   Just the roof, from the trailing edge of the feed tube to the leading edge of the riser.
Stock specs call for this to be 10" up to 12." I built one at 15"... BUT, only one time.
I had to do a mid-winter teardown to shorten that build. It seemed to burn OK, but was filling my pipes with ash.

Those two barrels share plenty of heat while burning, but they also shed plenty of heat when not burning.

3" is now considered to be a good gap for riser to barrel clearance.

My 8" J-Tube in an uninsulated greenhouse in northern Montana was run nonstop from apx 7 AM to 10 PM all winter long.
I call it extreme burning. With an exposed barrel and 45' of buried 8" piping, we could easily top 80F while it was in the low teens outside.
My chimney exhaust gas temperatures were well over 340°F; they should be 180°F- 220°F.
By 7 AM the next morning, it would be in the low forties or upper thirties and dropping steadily.

My new all-brick double bell first-generation BatchBox is in the exact location. And easily brings the room to the lower sixties with three fires a day.
The next morning, it will be in the upper fifties and creeping downward at a tenth of a degree every half hour or so.

Hi Eugene;

An 8" J-Tube has more than just a few sticks burning. With a 7.5" throat, wide open all the time, they roar.
After many modifications, they have been "maxed out" in terms of output.

A 6" Batchbox derives its power, not from the size of the load of wood, but from the size and shape of the box and the port size in the back, and receives a supercharge of cool oxygen through the secondary air tube at the throat of the port, creating a cyclone or double rams horn of fire reaching greater burn temperatures than a J-Tube can create.