Yezzir

1. VARIABLE AIR VOLUME (VAV) SYSTEM WITH TRACKING RETURN FAN

1. Variable Air Volume Control

        1. On start up the inlet vanes shall be in the minimum position.
        2. A static pressure controller shall, through the DDC panel, modulate the variable volume vanes as required to maintain the desired end of line duct static and space static where applicable.   End of line duct static shall be sensed approximately 2/3 the distance from the supply fan to the end of the duct.   Actual end of line duct static sensor location shall be determined by system design and shall be the responsibility of the DDC installer to insure correctness of operation.

2. Occupied cycle

        1. The unit fan shall be started and stopped from the central monitoring and control FMS system.   Return fan s/s shall be interlocked with supply fan.
        2. When the unit supply fan is started, the outdoor air dampers shall assume their minimum design position (approx. 10%).   The mixed air and exhaust air dampers shall assume their corresponding design positions.   Provide a morning warm-up cycle, which shall maintain the outdoor air dampers in a closed position until return air temperature is 70 degree F (adjustable).
        3. A mixed air sensor, averaging type, shall (through its DDC panel) override the control of the outdoor air, mixed air, return air and exhaust air dampers as required to prevent the mixed air temperature from falling below 55 degree F.
        4. Summer/Winter Switch-over - Switch system to summer operation when the following conditions have been met:

              1. Space temperature indicates cooling is required.
              2. Outside air temperature indicates cooling is required.
              3. Cooling is available.   e.g. Chilled water is available from central chilled water system or local package unit.
              4. CWS temperature sensor indicates that cooling is available...