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I I n n s s t t a a l l l l a a t t i i o o n n - - M M e e c c h h a a n n i i c c a a l l
to be installed at this time.
6. If using a cooling tower, refer to
a typical piping circuit from the unit.
7. Ensure the water pressure to the unit does not
exceed 400 psig.
8. It is recommended that water pressure is applied
prior to fan cassette installation.
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.
N N o o t t e e : : To prevent water pump damage, design system
piping to provide relief when using energy
saving waterside economizer valves.
Condensate Drain Connections
N N o o t t e e : : 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
32
Figure 16, p. 32
for
removal, include a shutoff/balancing valve on the
entering and leaving waterside pipes, drain tees, and
unions of each unit.
N N o o t t e e : : Unit does not have floor drains.
Figure 16. Condenser water piping components for
cooling tower system
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.
N N o o t t e e : : 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.
PKG-SVX027C-EN
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