Slimline Indirect Twin Coil Hot Water Storage Cylinders

  • Internal Expansion or sometimes called 'bubble top' in the trade make use of a self-generated air gap created in the top of the cylinder. This occurs on initial filling of the cylinder due to its clever design. The hot water draw off pipe is extended inside the cylinder creating a dip tube and water can not fill past this point. This air gap can sometimes be lost over a period of time and can only be replenished by partly draining the cylinder.
  • External Expansion is a physical expansion vessel fitted to the incoming cold water supply. Correct positioning of the expansion is important.

Select Internal Expansion or External Expansion