TABLE OF CONTENTS The following explain some of the more fundamental terms encountered when considering boilers.
This is a boiler in which the products of combustion or hot gases pass through a series of tubes surrounded by water. All are contained in an outer shell.
In a watertube boiler water circulates through small-bore tubes constructed in banks and connected to drums or headers. The external surfaces of the tubes are exposed to the products of combustion or hot gases.
This is a horizontal shell boiler where the gas-reversal chamber from the combustion tube to the first pass of tubes is external to the rear tube plate and is formed by a refractory lined steel chamber.
A wetback boiler is a horizontal shell boiler where the gas-reversal chamber from the combustion tube to the first pass of tubes is integral within the boiler shell and surrounded by water.
This is a term applied to the early free-standing shell boilers of two- and three-pass construction. Originally, they were dry back and later wet back. These boilers superseded the brickset Cornish and Lancashire boilers. The earliest economic boilers were also brickset. The gases from the front smokebox returning across the lower external part of the shell were contained within the brick setting to form a third pass.
A packaged boiler is a concept of a factory-built and...
