Longer Batchbox - Anyone taken up Peterberg's invitation?

[wrekinwanderer]

Anyway, I'm considering lengthening the batchbox for my 6" system, to try and get a bit of a longer burn and some more energy going into my Apostol Engineering style water heater. It took me ages to finally track down what Peterberg had to say about a longer batchbox and finally found it on the last page of the Adventures with horizontal feed...

It ends with an invitation from Perterberg, which I shall repeat below:

The combustion efficiency is halved when loaded half of the firebox. The best efficiency is achieved when the firebox is loaded to a level well above the port. So, somebody has to build one with a lowered firebox ceiling and a slightly lower and wider port. That way, the stove could be loaded for 3/4 again and all would be well. This is an entirely different experiment, not to be performed by me.

Have any of you lot had a go at lowering the ceiling and changing the port dimensions?

[grizbach]

Each build will need a different box size/primary intake according to the draft. The draft of each setup is a main variable of the equation.

[wrekinwanderer]

Of course. But that's where the ratios come in isn't it?.....

[grizbach]

I'll use my build as an example.
The maximum I can fill my batch box is about 7/8. Even this can be overly rich at times. I am safe at 3/4 full.
Now this is maximum efficiency for my build. If I had a stronger draft or less bells, I could fill the box all the way and have an efficient burn.

By lowering the ceiling, you are talking about changing the fuel charge aren't you?

[wrekinwanderer]

The quote where "lowering the ceiling" comes from is from Peterberg. I assume it means decreasing the height of the firebox, thereby changing the batchbox ratio.

[satamax]

I have a diferent ratio on mine, 30x30 X47~ for the one in the water heater (green thing if you've seen it. And 30x30X50 on the 8 incher barbecue. What i find with the barbie, it's that it takes à while to heat up. Both systems are horizontal batch rockets. With no Pchanel.