The ''OAS'' outside air sensor allows precise real time monitoring of the outside air temperature on your zoned HVAC system. The optional ''OAS'' wires directly into the BMPlus series, UZC4 series or UT3000 control panels allowing the control system to monitor the outside air temperature. Using the adjustable potentiometer on the control panel or the LCD menu, the installer can set the desired outdoor temperature changeover setting, to engage supplemental or backup heating systems. The OAS comes standard with the HK2000 Economizer system. The OAS is a versatile device because it can be mounted on an outside wall or an outside air duct. Make sure the OAS is mounted completely outside of the house. Avoid direct sunlight. Do not mount the OAS low to the ground where snow can cover it. Do not mount the OAS close to exhaust vents of any type. Use a dedicated 2 conductor 18 AWG solid copper jacketed thermostat cable to connect the OAS to the zone control system, Economizer or the Smart Humidistat. Avoid running cable in close proximity to line voltage circuits, or inside a conduit with other circuits. Avoid wire runs in excess of 100 ft.