Carrier 50FK, JK034-074, 48FK specifications Thermistor T2 Location, Size 034-048 Units

STANDARD	BAG
FILTERS	FILTERS

Fig. 11 Ð Thermistor T2 Location, Size 034-048 Units

STANDARD FILTERS	BAG FILTERS
	(054-074 Only)

Fig. 12 Ð Thermistor T2 Location, Size 054-104 Units

Economizer Ð Economizer control is used to control the outside and return air dampers of the unit, to satisfy space cooling demand using all outside air (when permitted), and to satisfy cooling in conjunction with compressor operation (when conditions permit). During Occupied periods without cooling demand, the outside-air dampers will be at the user- con®gured Minimum Damper Position (at P5 on accessory board). During Unoccupied periods, the outside-air dampers will be closed.

The economizer is available as a factory-installed option. The user can install an accessory differential enthalpy sensor to enhance economizer control. Refer to the installation sec- tion for ®eld wiring of the sensor.

Fig. 13 Ð Thermistor T3 and T4 Locations,

Size 034-048 Units

ENTHALPY CONTROL Ð Outside air enthalpy control is standard with the factory-installed economizer option. En- thalpy is sensed by a controller located behind the end out- side air hood. The control can be accessed by removing the upper hood ®lter. See Fig. 17.

DIFFERENTIAL ENTHALPY Ð Added efficiencies in econo- mizer control can be gained by installing a differential en- thalpy sensor in the return air duct. When differential enthalpy control is installed, the economizer control will use the air stream with lower enthalpy (outside air or return air) to pro- vide for lower compressor operating costs during integrated economizer cycle operation. The differential enthalpy sen- sor is installed in the return-air duct.

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