Installation - Mechanical
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PKG-SVX027A-EN
9. Install differential pressure switch on the water inlet
and water outlet. Unit control scheme will trend water
pressure drop and alert user when internal 20 mesh
screen needs to be cleaned.
10. Fill and leak check water side connections.
Note:
To prevent water pump damage, design system
piping to provide relief when using energy saving
waterside economizer valves.
Condensate Drain Connections
Note:
Unit is not internally trapped. Installer will need to
provide an external trap for unit to operate
properly.
Locate condensate drain on the unit. 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 for
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.
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 condenser piping in reverse
returns. This helps balance the system by equalizing the
length of supply and return pipes. Multi-story 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 startup 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 startup 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.
Note:
Unit does not have floor drains.
Water Temperature 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 (intermediate 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.
Water Piping Verification
•
Make return and supply water connections to the unit
and/or waterside economizer piping package with
recommended valves and piping components.
•
Install unions to allow waterside maintenance.
•
Install cooling tower and standby pumps.
•
Treat water to prevent algae, slime, and corrosion.
•
Prevent refrigerant piping from rubbing against other
objects.
Refrigerant System
Modular Self-Contained Units ship with a dry nitrogen
holding charge.
Before installing refrigerant piping, verify holding charge
is present. Momentarily depress the MSC suction or
discharge line (and condenser liquid line) access port
valves.
If charge is present, continue with piping installation.
Figure 15.
Condenser water piping components for
cooling tower system
