Variomat pressurisation systems maintain pressure by means of a pump in the hydraulic system.
- When the set pressure is exceeded, the overflow valve opens and releases water from the system into the expansion vessel. The water in the vessel increases and the pressure in the system drops.
- When the pressure falls below the set pressure, the pump switches on and pumps water from the expansion vessel into the system: the water content in the vessel drops and the pressure in the system rises.
In the Variomat, degassing is part of the performance range. A partial flow from the system is routed into the expansion vessel by a timer and de-pressurized there. Released gases escape under slight overpressure through a special fitting.