Preassembled compact kit combining the components required for balancing, control, flushing and commissioning of HVAC terminal units (fan coils, chilled beams, etc.) with the main distribution network. The kit consists of a diverting ball valve to bypass the unit, a full-port ball valve with integrated filter, a pressure independent control valve (PICV), a drain cock and four pressure ports to measure the differential pressure and the flow rate. Thanks to the two ball valves it is possible to clean the filter and operate on the unit with no need to drain the entire system. The kit is quick to install thanks to the use of only four connections which also prevent possible errors. Its pressure independent control valve (PICV) enables to regulate and keep constant the flow rate in the terminal unit when the differential pressure of the main circuit varies. The terminal unit can also be isolated and the flow can be bypassed through the ball valves installed. The water flow entering the terminal unit, which also runs through the PICV, is filtered by the filter integrated in the shut-off ball valve. The drain cock drains the water during maintenance and flushing operations.