Roger - I think you and I exchanged some thoughts on this at an earlier time? You saw the picture of what I did with my E-2300?? I'll add it again here. I too, am considering a re-design when I have a few bucks.
I feel there is something to be said for introducing the primary air near the bottom of the firebox as the original design does. My first design does work very well, though I still need to restrict the primary air flow a bit, tried the other day but the solenoid is down as low as I think I can put it already. So I may for now just screw in a bushing on each side of the T and see what that does.
For my re-design, I'm thinking this... The original design had my air channel welded to the sidewall and had a flat top sort of making a notch in the wall. You can see it in the picture. That's where the original design called for 2 lifts of firebrick to be layed in against the wall. So if I come out through the back wall with my 2" pipe to a T, first one aiming up and down, have a nipple go down to rest on the firebox floor again as I have now (allowed for extra support for the design I'm using now, but also a creosote drain). On the top side, put a short nipple up to another T aiming crossways and pipe to each side, then elbow toward the front. I could piece it all together using nipples and T's for outlets. Add bushings into the T's to restrict flow a bit. And the side pipes could be sized down to maybe 1" or 1 1/4". Have maybe 3 or 4 outlets up each side and I would have them blow down at an angle toward the coal bed.
I think there is a lot to be said for air directly at the fire. With the original air channels I did have a more even coal bed. Now it is more centrally located at the nozzle. Also, on each of the Ts used for outlets (elbows in each end I would say) I would use bushings on the outlets to size them down. And finally, regarding the bushings, have bushings with smaller holes at the back and get slightly larger at the front as there is less air pressure remaining there. This would mimic the original design pretty close, but would be removable for cleaning. I also have the added benefit of allowing the new channel to rest on top of the old one. In your case, at the front end of your channels, provided you are doing a similar design, you could elbow down with a nipple to the firebox floor to support it on each side.
Something else I have going for me is that I've already added the spacer bar kit (bars hanging down my sidewalls to keep the wood away and allow air around it better. I don't know about your setup since I think you have them built in. With my add on bars, they can rest against my air pipe to keep the wood from fetching up on the air pipe.
This is my $0.03 worth. It's a bit more than $0.02 I think. Given my experience with what I've already done and learned, I think this is a good plan. I think you already have similar thoughts. Hope my ideas can be of some help. Good luck!! and keep us posted!!
Jeff
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