Standard Sized Indirect Unvented Hot Water Storage Cylinders

  • An internal expansion gap or sometimes called a 'bubble top' makes use of trapped air within the top of the cylinder to accomodate the expansion of the stored water when heated. Sometimes the air gap is lost over time and is re-established by part draining the cylinder.
  • External expansion cylinders have an potable expansion vessel installed on the incoming cold main supply to accomodate the expansion of water when heated.

Select Internal Expansion or External Expansion