Trane Modular 20 to 35 Tons Parts List download pdf (Page 82)

82 PKG-PRC003U-EN

Mechanical Specifications

operating efficiency. An outside air temperature and relative humidity sensor are provided to allow

monitoring of reference enthalpy and are field installed. Economizer operation enables when the

outside air enthalpy is less than 25 BTUs/lb. default (adjustable 19-28 BTUs/lb.). 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.

The mixing box fabrication is galvanized steel. Opposed low leak damper blades are galvanized

steel and rotate on rustproof nylon bushings. A factory installed 24V modulating spring return

actuator controls both damper positions.

Comparative Enthalpy Control

Units with comparative enthalpy control 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 control board, with field-installed outside and return

air temperature and relative humidity sensors, allows monitoring of outside and return air.

Economizer operation enables when the outside air enthalpy is 3 BTUs/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.

The mixing box fabrication is galvanized steel. Opposed low leak damper blades are fabricated

from galvanized steel and rotate on rustproof nylon bushings. A factory installed 24V modulating

spring return actuator controls both damper positions.

StandardTwo-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 BTUs/lb. (adjustable 19-28 BTUs/lb.). 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).

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 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

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Trane Modular 20 to 35 Tons Parts List Page 82

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