Trane Modular 20 to 35 Tons Parts List download pdf (Page 83)

PKG-PRC003U-EN 83

Mechanical Specifications

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. An analog 2-10VDC output (adjustable (0-10VDC) is provided to modulate

the field-provided 30-second damper actuators (adjustable 1-255 seconds).

Basic Water Piping

This option is available on units without a waterside economizer and with condenser water

applications above 54°F that do not require condensing pressure control. Left hand water

connections and piping are extended to the unit exterior. Manifold piping is factory installed.

Intermediate Water Piping

This option provides condensing temperature control when the unit is configured (user defined at

the HI) for variable water flow with or without a waterside economizer. A two-way modulating

control valve is wired and installed in the unit to maintains a specific range of water temperature

rise through the condenser when entering fluid temperature is less than 58°F.This option allows

the compressor to operate with entering fluid temperature down to 35°F.The minimum valve

position to maintain minimum condenser flow rates is user-defined at the human interface.This

valve drives closed if the unit shuts down or if a power failure occurs.

Waterside Economizer Flow Control

Units equipped with a waterside economizer can be set from the human interface panel for variable

or constant water flow.

Constant Water Flow

Two-way modulating control shutoff valves are wired, controlled, and installed in the unit. One

valve is located in the economizer’s water inlet, and the other is in the condenser bypass water inlet.

When the waterside economizer enables, the two-way valves modulate to maintain the discharge

air temperature setpoint. As the economizer valve opens, the condenser bypass valve closes, and

vice versa. Full water flow is always maintained through the condensers. Both valves will close in

the event of a power failure.

Variable Water Flow

Two-way modulating control shutoff valves are wired, controlled, and installed in the unit. One

valve is located in the economizer’s water inlet, and the other is in the condenser bypass water inlet.

When the economizer valve is active, the condenser bypass valve closes.The economizer valve

modulates, thus water flow through the unit is modulates. If the water is cool enough for

economizing, but mechanical cooling is also required, the economizer valve fully opens to establish

full water flow through the condensers.Whenever the water is too warm for economizing and there

is a call for cooling, the economizer valve fully closes and the bypass valve fully opens, establishing

full water flow through the condensers. Full water flow is always maintained through the

condensers when mechanical cooling is required. Both valves close whenever cooling is not

required, and in the event of a power failure.

Water Flow Switch

A water flow switch is factory installed in the condenser water pipe within the unit. Whenever the

flow switch detects a water flow loss prior to or during mechanical cooling, compressor operation

locks out and a diagnostic code displays. If water flow is restored, the compressor operation

automatically restores.

Service Valves

Service valves are factory installed on each circuit before and after the compressor to allow

compressor isolation for servicing.

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Trane Modular 20 to 35 Tons Parts List Page 83

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