Back-boiler for domestic fireplace - has rear water tube nest screened by water jacket in communication with headers

摘要

The back boiler consists of a vertical tube nest (4) at the back of the fireplace with a top and bottom header (5,6). The fire bars (10) are water tubes connecting the bottom header (6) to a horizontal under-hearth water jacket defined by a pair of plates (2,3). In front of the vertical tube nest (4) is a second water jacket (23) which is connected into the tubular fire bars at it's base and into the top header (5). The headers and both water jackets are divided into right and left hand sections. Water entering the back boiler at the inlet (12a) descends in the left hand half of both the tube nest and the vertical water jacket and flows to the front of the left hand fire bars to enter the underhearth water jacket and flow back to the rear of the latter.