Knowing the following data:

  1. The minimum operating pump pressure
  2. The maximum operating pump pressure
  3. The plant maximum absorption
  4. The maximum allowable pump starts per hour

it’s possible to calculate the required volume of the expansion vessel.


  • The water volume of the system is the one after the non-return valve or after the pressure reducer.
  • The set pressure of the safety valve must be lower than the maximum working pressure of the vessel.
  • The precharge pressure should be set at 0.2 bar less than the minimum system pressure.
  • The calculation provides only an indication of the required volume of the expansion vessel and must be verified by a specialized and authorized technician.