Trane Modu manual Air-Cooled Condensers, Airside Economizer Interface with Comparative Enthalpy

General

Owner Information

Standard Two-Position Damper Interface Units with the two-position damper interface are provided with a 0-10 VDC control output suitable for controlling a field-provided modulating actuator. In occupied mode, the output drives to the maximum position.

Airside Economizer Interface

Units with airside economizer interface are equipped with the necessary control sequences to allow using outside air for the first stage of cooling, in occupied or unoccupied mode and when ambient conditions are favorable for economizing. Inherent in the unit controller is the ability to suppress the setpoint below the normal unit setpoint. This allows the building to improve comfort levels when possible, and at the same time, optimize building mechanical cooling operation for peak operating efficiency. An outside air temperature and relative humidity sensor are provided for field installation to monitor reference enthalpy. Economizer operation enables when the outside air enthalpy is less than 25 BTU’s/ lb. (adjustable 19-28 BTU’s/lb.). During occupied mode, the outside air damper opens to 15% (adjustable 0-100%) for ventilation purposes. Also, the ability to

control board, with outside and return air temperature and relative humidity sensors, are provided for monitoring outside and return air.The sensors are field installed. Economizer operation enables when the outside air enthalpy is 3 BTU’s/lb. less than the return air enthalpy. During occupied mode, the outside air damper opens to 15% (adjustable 0-100%) for ventilation purposes. Also, the ability to alter the outside air damper position to compensate for VAV supply air modulation is inherent in the unit controls, and can be enabled by the operator. An analog 2-10 VDC output (adjustable (0-10 VDC) is provided to modulate the field-provided 30-second damper actuators (adjustable 1-255 seconds).

Air-Cooled Condensers

SXRG units are designed for use with the remote air-cooled condenser, model CXRC. For more information, see the air- cooled condenser Installation, Owner, and Diagnostic Manual, CXRC-SVX01A-EN.See Table O-GI-10 for CXRC refrigerant connection sizes.

Condenser fans will stage per a user- defined setting. If the condenser is equipped with head pressure control (air modulation on last stage of condenser capacity), the condenser airflow will modulate to maintain condensing temperature setpoint. Condensing temperature is determined by sensors located at each condenser coil.

alter the outside air damper position to compensate for VAV supply air modulation is inherent in the unit controls, and can be enabled by the operator. An analog 2-10 VDC output (adjustable (0-10 VDC) is provided to modulate the field- provided 30 second damper actuators (adjustable 1-255 seconds).

Airside Economizer Interface with Comparative Enthalpy

Units with airside economizer interface and comparative enthalpy are equipped with the necessary control sequences to allow using outside air for the first stage of cooling, in occupied or unoccupied mode and when ambient conditions are favorable for economizing. Inherent in the unit controller is the ability to suppress the setpoint below the normal unit setpoint. This allows the building to improve comfort levels when possible, and at the same time, optimize building mechanical cooling operation for peak operating efficiency. A factory-installed

Figure O-GI-6. CO2 Reset Function, Outside Air vs. CO2.

Table O-GI-10. Remote Air-Cooled Condenser Refrigerant Connection Sizes - English inches (Metric, mm)

Unit	Circuit 1		Circuit 1	Circuit 2		Circuit 2
Size	Liquid Line		Discharge Line	Liquid Line		Discharge Line
CXRC 20, 25, 29, 30	5/	8	1 1/	5/	8	1 1/
			8			8
	(16)		(29)	(16)		(29)

88 SCXG-SVX01B-EN