In Variomat pressurisation systems, the pressure is regulated through the use of a Pump in the hydraulics system.If the set pressure is exceeded, the overflow valve opens and allows water to flow from the system into the expansion vessel. The water content in the vessel rises and the pressure in the system falls.If the pressure undershoots the set pressure, the Pump switches on and pumps water from the expansion vessel into the system, the water content in the vessel falls and the pressure in the system rises.With the Variomat, degassing is part of the performance spectrum: Using a timer, a partial flow is directed from the system into the unpressurized expansion vessel, where it is depressurized. Gases released in the process escape at a slight overpressure via a special fitting.