HVAC system with volume modulating valve

An HVAC system, comprising:

• an outdoor VRF unit configured to supply coolant with a compressor;
• an indoor fan coil unit configured to receive coolant from the outdoor VRF unit;
• an air duct network connected to the indoor fan coil unit;
• a plurality of volume modulating air valves connected to the air duct network;
• and,
• a plurality of thermostats, each of which is connected to one of the plurality of volume modulating air valves;
• wherein each of the volume modulating air valves are configured to 1) restrict passage of air to match a predetermined target volume for heating or cooling based on commands from one of the plurality of thermostats and 2) enter a vent mode when a respective connected thermostat reaches a temperature set point;
• wherein the vent mode of each of the volume modulating air valves maintains an open state at 40% or less of the predetermined target volume for that respective thermostat;
• wherein the compressor of the outdoor VRF unit maintains operation when at least one of the plurality of volume modulating air valves is delivering the predetermined target volume for heating or cooling;
• and,
• wherein the compressor of the outdoor VRF unit reduces operation to as low as 30% when at least one of the plurality of volume modulating air valves is delivering the predetermined target volume for heating or cooling.