Trane SCXG-SVX01B-EN Mechanical Specifications, General Waterside Recommendations Cooling Towers

Mechanical Specifications

Condensate Drain Connections The condensate drain is internally trapped. Condensate drain connections are on the unit’s left side. Connect condensate drain piping to the 1 1/4“ NPT female fitting, using at least 7/8” OD copper or 3/4“ OD iron pipe. Pitch the condensate line downward a minimum of 1/2” for each 10' of horizontal run, away from the unit. Be sure to install the condensate drain “P” trap drain plug. Before starting the unit, fill the trap with water to prevent negative pressure in the fan section from impeding condensate flow.To facilitate drain pipe cleaning, install plugged tees in place of 90°elbows.

General Waterside Recommendations: Cooling Towers

Cooling tower control affects the unit cycle rates. Condenser water temperature swings from 10-15°F may cause excessive compressor, water valve, and unit cycling. Be sure to set the tower controls to minimize compressor/ unit cycling.

Table I-MR-1. Water Connection Sizes.

Unit Size	Direct Condenser	Factory	Piped
SCWG 20-35	1-1/2 NPT	2-1/2	NPT

Waterside Piping Arrangements

Install a condenser water pump between the cooling tower (either open or closed) and the self-contained unit. Lay out the remainder of the system’s condenser piping in reverse returns.This helps balance the system by equalizing the length of supply and return pipes. Multistory buildings may use a direct return system with balancing valves at each floor.

Install the supply riser and its return in close proximity. Furnish both with permanent thermometers to check the waterside balance during start-up and routine maintenance checks.

Also, include strainers at each pump inlet and unit. Install drain valves at the riser’s base to allow drainage points for system flushing during start-up and routine maintenance. For condenser draining and header removal, include a shutoff/ balancing valve on the entering and leaving waterside pipes, drain tees, and unions of each unit. Also, install a shutoff valve on the unit entering water pipe for condenser draining.

Note: Unit does not have floor drains.

WaterTemperature Requirements Do not allow the entering water temperature to go below 54°F (12.2°C) on units with constant water flow (basic piping). This will cause the compressors to shut down and the mechanical cooling function will lockout. However, the economizer (if enabled) will continue to function.The compressors will reset when the entering water temperature reaches 58°F (15°C).

Units with variable water flow (intremediate piping) have a modulating condensing pressure control valve that allows compressor operation down to entering water temperatures of 35°F (2°C).

For more information on constant and variable water flow, see the Sequence of Operation section of this manual.

Note: Units with a waterside economizer can be set from the human interface panel for variable or constant water flow.

Figure I-MR-2. Condenser water piping components for cooling tower system

Figure I-MR-3. Direct condenser connections.

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