VRF (Daikin VRV) like ductless minisplits VRFs use refrigerant as the cooling and heating medium.
This refrigerant is conditioned by a single outdoor condensing unit, and is circulated within the building to multiple fan-coil units.
VRFs come in two system formats, two pipe and three pipe systems. In a heat pump 2 pipe system all of the zones must either be all in cooling or all in heating.