CAL-PRO Expansion Vessels


CAL-PRO: are membrane expansion tanks for centralized closed circuits suited to absorb the increased water volume when the temperature in the heating system increases. It has an SBR membrane and produced according to PED norm 2014/68/EU for centralized non potable water heating systems.


Technical Specifications

  • Max. working pressure mod 4-8 litres - 5 bar
  • Max. working pressure mod 12-50 litres - 4 bar
  • Max. working pressure mod 80-900 litres - 6 bar
  • Operating temperature  -10/+99°C
  • Factory precharge mod. 4-50 litres  - 1,5 bar
  • Factory precharge mod. 80-150 litres  - 2 bar
  • Factory precharge mod. 200-900 litres  - 2,5 bar


The CAL-PRO range of Expansion Vessels is specifically designed for domestic and commercial unvented central heating systems.The purpose of these vessels is to accommodate the increased liquid volume which occurs during system heating in an Unvented Circuit. A pressurised membrane allows ingress/egress of the liquid only during periods of heating / cooling.

The correct size of vessel must be considered prior to installation and installed by appropriately trained engineers.

Installation Siting

The Expansion Vessel must be fitted to the Return Side of the Central Heating System and in such a way that there can at no time be an obstruction between the vessel and the system.

The orientation of the expansion vessels Water Connection should be downwards to avoid risk of sediment ingress or other debris from the system. Some provision for the prevention of air ingress into the vessel must also be made as this will degrade the vessel very quickly.

Adequate provision for the mounting of the expansion vessel must be made by the installer and a suitable bracket or other mounting method used. A range of suitable brackets are available as accessories.


Download Installation & Operations Guide