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 http://batchrocket.eu/