With succes I build a RMH with a 15 cm/5 inch pipe system. This was a burner with a strait bench.
Now I want to build one in a L-shape. As there is not a lot of room for more, the max length of the short part of the L (see attachment) is 1.20 m / 47 inch.
Anybody any insight if these short-after-oneanother-bendings will have a lot of influence on the draft .. ?
I've seen plans for a similar RMH by Ernie and Erica Wisner called "The Annex". It was 6" pipe and a little longer, but had the same number of bends. I have no hands-on experience but from all I've read the critical part is a well insulated riser and good heat transfer cooling the exhaust on its way back down to the bench. This should essentially double the convection force, pushing the exhaust through the pipe in the bench. I would be more concerned about appropriate scaling, sizing the riser to the pipe, than the number of bends or how close they are to each other.
Please note this is armchair engineering but I've read enough real life experiences that I'm confident it should work as long as the other components are well designed and properly scaled to the system.
I do have a copy of the plans for "The Annex", but I'm not sure if I have the right to distribute it. I got it through a free promotion but I have seen it for sale.
Try this link to get it for free.
Location: Czech Republic; East Bohemia; Latitude 50˚ 12' 34"
posted 3 years ago
15 cm is equivalent to 6 inches and 20 cm is equivalent to 8. So from your picture if you have a tall chimney it seems like you are within the length that Erica and Ernie set forth for a 6" system. You start with 11-12 meters and subtract 1.5 meters for every 90˚ elbow but add 3 meters for a tall chimney. Seems like you are right there.