The Beam Engine at Tees Cottage requires steam to generate power. This steam is produced in one of two Lancashire boilers, which were installed in 1902. Currently only one boiler is used for this purpose.
The boilers each contain 5,500 gallons of water and take seven days to warm up from cold. Gradual warming is necessary to reduce the thermal stress on the boiler so helping to preserve it for as long as possible. The energy required for the warming process is provided by the burning of waste wood but on each open day this is replaced by coal. Half a ton of coal is consumed each day for this purpose.
The fuel (waste wood and then coal) is ignited in each firebox and the resultant hot gases then pass through two tubes which run through the water contained in the boiler drum. These gases heat the water to boiling point, creating steam. The steam escapes through a pipe at the top of the boiler and is fed to the Beam Engine.