During the 19th and early 20th century, there were five boiler-houses at Pleasley Colliery.  There was one on each side of the North and South engine-houses with another to the SW of the fan-houses.  All the boiler-houses were originally enclosed and covered over by a double ridge slate roof with glass lights and ventilation cowls.

There were four boilers in each of the engine-house boiler ranges but there may only have been two in the fan range initially.  In 1890 a generator driven by steam from the fan boilers was installed and the fan range appears to have been upgraded to four boilers served by a short railway siding.

Following the 1922 deepening of the South pit, the main boilers were consolidated into a single range along the the east side of the engine-houses and the west side ranges were discontinued.  The ventilation fans were later converted to electric drive, the boilers removed and chimney demolished. The beds of the boilers were then converted into 4 sedimentation tanks (possibly for water from the early washery plant).

Sedimentation tanks at site of the old fan boilers circa 1932 (FoPP)