Design Considerations

Every example of a Rhodesian boiler was built with whatever materials were to hand. As a result, there are nearly as many different designs of boiler as they are boilers. Nevertheless, this basic design is common to most:

Features

• most were constructed from burnt brick (made from ant heap) and were assembled with clay mortar, most often with the addition of lime or ash
• the roofs of the older examples were likewise constructed from a plastered vault of burnt brick; later editions often sported a flat concrete roof
• most chimney stacks were of the same brick construction, with inner dimensions of 6-8" (150-200mm) - others were made from a section of 6" iron or asbestos pipe
• most fireboxes extended the full width and length of the drum
• some were equipped with a fire grate, but most had no grate
• the drum was supported above the firebox with two or more fencing standards
• the length of the stand pipe generally remained within 10 feet (3 m), to keep the pressure in the drum below 5 psi (30 kPa)
• cold water could be fed directly to the boiler, however, if the pressure in the cold supply exceeded 3m head, the boiler either had to be raised on a plinth or a separate header tank had to be constructed for the boiler
• when the domestic water supply came from a tank on a ceiling height stand, the boiler would be raised on a plinth, in order to raise the bottom of the drum 3-4 feet (1.0-1.3m) off the ground thus keeping the pressure in the drum below 3m head.

Operation 

Boilers were generally fed twice per day, at dawn and sundown, with two or three large hardwood logs. For the remainder of the day, the fire remained smoldering; from time to time, one of the logs would be shoved further into the ash bed. The water was, therefore, scorching hot in time to do the milk buckets for the morning and evening milking, and remained sufficiently hot for ablutions and dish washing the rest of the time.

In fair weather, a bath could be drawn within 30-40 minutes of firing up (from cold), and the better examples would provide hot water for morning ablutions before being fed. With the fire stoked, hot baths could be drawn in an endless succession even when the house was full of guests.

The efficiency varied tremendously, some consumed two or three times as much firewood to get the job done, and poured flames and smoke from every orifice: