Model, scale 1:12, of balloon or haystack boiler

The haystack boiler was the earliest type of boiler used alongside steam engines. It was typically employed with atmospheric engines, providing steam at very low pressure only, and was often positioned beneath the engine's cylinder, surrounded and supported by a brick-built setting which allowed for the provision of a surrounding heating flue, to maximisse the amount of heat conveyed to the water within. The boilers were fabricated from wrought iron plates, riveted together, and when they had finished their working lives the wrought iron shells often found new uses, as water tanks or even as shelters for horses.