Leo is a volume flow controller which works independently of the duct pressure. It is the desired air flow rate at choked damper that determines the duct pressure required for the applicable unit/string. The VAV unit is based on dynamic measurement of volume flows, and controls the damper position to maintain the air flow rate required. When a change in duct pressure occurs, such as when other volume flow controllers on the branch open or close, the unit will compensate by adjusting the damper until the correct volume flow has been restored. The required air flow rate can, for example, be provided as a 0-10V signal from room thermostat / CO² sensor in the occupied zone covered by the unit. Minimum and maximum air flow rates can be set at the factory or during installation by using a service tool from Belimo or Siemens. The VAV unit is designed to provide comfort ventilation at temperature conditions of between 0°C and 50°C and a relative humidity between 5% and 95% without condensation. A 4-conductor cable connects the controller to various control equipment in the room. Consistent use of a common reference system for all equipment is important. For the VAV controller, cable no. 1 is system-0. All control and measurement signals are linked up in accordance with this. For energy-efficient operation, VAV systems are equipped with pressure sensors in the ductwork, which transmit control signals to branch dampers or to the fan frequency control.
Leo VAV is a complete measuring and control unit where the air flow rates in ventilation systems can be set as required. At the measuring station, the differential pressure is measured via measuring rod integrated in the unit. The unit is installation-friendly in terms of straight ducting, and can thus be mounted in most ductwork sections. It is fully compliant with air permeability class 4 for damper in closed position, and class C for leakage to the surroundings. Leo is equipped with VAV controller from Belimo or Siemens.
Leo comes in a galvanized steel design. The measurement unit is in aluminium. Tubing, nipples and motor casing are in plastic. Leo's connection collars are fi tted with EPDM rubber gaskets. LEV is made of galvanised steel, and comes with mineral wool and a glass fi bre layer as attenuation material. Connection collars are fi tted with EPDM rubber gaskets. ASN is made of galvanised steel and is equipped with an EPDM rubber gasket on the connection collar.