It'ss no secret that in the VRF systems (either single or multi VRF) the compressor(s) acts dual role: producing heat and cool, but also being a hydraulic pump, transporting the refrigerant betw. external and internal units.

Depending on the overall length and height betw. the external and all internal units, diameters of the pipes and number of elbows (45o/ 90o), additional capacity must be added on the top of the demanded cooling/heating capacity (based on cooling loads and heating losses)

This additional capacity is very often varying between. 20-40%. Together with that significant additional refrigerant quantity must be charged as well.

VMF on the other side has only 1 internal unit and that is IHU (Internal Hydraulic Unit), and thus capacity losses are minimized (2-5%). The cool/heat of refrigerant who's being transferred into water within IHU is transported to all internal units via highly efficient and energy saving water recirculation pumps with low PI. Damvent's tests show that VMF Heating Power Input (kW) (incl. Heating, Ventilation and Pumps) is -15 to -30% lower than top VRF`s (heating only, without Ventilation)!

Another significant disadvantage of the oversized VRF's is the capacity regulation of the external unit(s), where they cannot go down below 20-30% from the total capacity. That literally results in the inability of the whole system to provide cooling/heating capacity when only 1 or 2 internal units have demands.

While VMF provides much smoother regulation going down to 7-10% of Max. Capacity, and providing cool/heat for only 1 internal unit if required

…And last but not least- VMS has not only 15-30 % less PI(kW), but also 15-30% less demanded installed electric power- extremely important for every owner…