In Reflexomat pressure maintaining stations, the pressure on the gas side of the tank is controlled via compressor: If the set pressure is exceeded, the overflow valve opens and discharges air from the expansion tank. The drop in pressure on the air side causes water to flow into the expansion tank and the system pressure drops. When the pressure drops below the set value, the compressor switches on and delivers air to the air side of the expansion vessel. This pushes the water into the system, the water level in the tank drops, the system pressure rises. For make-up and degassing, the Reflexomat can be equipped with additional devices. The option of intelligent integration of make-up is already integrated in the Control controller.

In Variomat pressurisation units, the pressure is controlled by the use of a pumps in the hydraulic system.If the set pressure is exceeded, the overflow valve opens and causes water to flow from the system into the expansion tank. The water content in the tank rises and the pressure in the system falls.If the pressure is below the set pressure, the pump switches on and delivers water from the expansion vessel to the system, the water content in the vessel falls, the pressure in the system increases. With the Variomat, degassing is part of the service scope: A time control system is used to direct a partial flow from the system into the depressurised expansion vessel, where it is depressurised. Consequently,at a slight positive pressure, the released gases escape via a special valve.