Large version of the single bourry box kiln

This is a dense firebrick salt kiln based on the single bourry box kiln plan, but it has been scaled up considerably to 107 cubic feet chamber volume. The critical proportions are A=10.3, B=5.8, C=16, D=23.8, where E=100 and V=9% of W.

Although we used it for a number of years there was always a temperature range from top front to bottom back of about 4 cones.

A better arrangement of exit flues, a slower firing schedule, more insulation, or improved user skill may have evened things out a bit, but we decided that it was always going to be a battle and became disenchanted with the design at this size. I decided to bring the chimney around to this side (in the photo), and add another firebox on the left, but did not get around to doing that.

Bigger kilns are more efficient than small kilns because the surface area of the box increases less rapidly than the chamber volume as the dimensions increase, so there is proportionally less heat loss through the walls. This firebox was unneccessarily large. It had a satisfying amount of power at full throttle, but firing the kiln quickly did nothing to improve the uneven temperature distribution.

Quite big logs could be dumped accurately on the hobs with this top loading bourry box, but the stoker received an alarming blast of heat. Carol usually had her arms fully covered.

SideStoke home | This kiln home

Carol stoking, 1987