rmh book questions

[eseating]

I am reading Ianto's book, and am wondering if anyone hear could tell me a couple things. I haven't built a thing yet, just gathering info at this time.
1)Talking about the feed tube he says it is best square or rectangular, not rounded. Why?
2) "Inspect the horizontal flue in your heat storage every month or two. If ash or soot is building up it can be cleaned out" with a brush or vacuum. Does this mean only at the cleanout? Because the rest of the tube will either be an S shape or will divide and come back together. I can't see how it would be possible to do a complete clean out in either case.
Thanks.

[hpmer]

1) I think the square comment has more to do with the burn tunnel than the feed tube, and that is because square promotes turbulence which helps mix the fuel and air for better combustion.

2) Ash can eventually accumulate downstream, so having clean outs to provide access is a good idea. Wherever you can't reach means that's where the ash will eventually build up, so it's probably best to have some access to all of it.