RECIRCULATION VALVESThe two re-circulation valves are shut-off butterfly valves. Each valveis mechanically actuated by a 28V DC motor and electricallycontrolled from the Ventilation Controller (VC). The recirculationvalves have two positions, open or closed. In closed position, thebutterfly still allows airflow through the valve, so they operate asrestrictors. Each valve has 2 limit switches for Fully Closed/Not FullyClosed (FC/NFC) and Fully Opened/Not Fully Opened (FO/NFO)position indication. There is a manual lever used to see the butterflyvalve position and to manually change it.