Operating Principles
48
PKG-SVX027A-EN
The valve can also be used for condenser system chemical
purge and condenser cooling loop system balance.
Water Flow Switch Option
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.
Waterside Economizer Option
The waterside economizer option takes advantage of
cooling tower water to either pre-cool the entering air to
aid the mechanical cooling process or, if the water
temperature is low enough, provide total system cooling.
The waterside economizer includes a coil, modulating
valves, controls, and piping. The coil construction is ½-
inch (13 mm) OD seamless copper tubes expanded into
aluminum fins. The evaporator and economizer coils
share a common sloped (IAQ) drain pan. Drain pan options
are either galvanized or stainless steel, and insulated.
The tubes are arranged in a staggered pattern to maximize
heat transfer. The coil has round copper supply and return
headers with removable clean-out and vent plugs.
High Duct Temperature Thermostat
An optional factory-supplied temperature limit switch with
reset element detects the supply air duct temperature.
This sensor should be field-installed downstream from the
discharge in the supply air duct. If the supply air duct
temperature exceeds 240°F (115.6°C), the unit shuts down
and displays a diagnostic. A manual reset is required at the
unit. High duct temperature can be adjusted at thermostat.
Dirty Air Filter Sensor Option
A factory installed differential pressure sensor senses the
pressure differential across the filters. When the
differential pressure exceeds a user selectable setting will
display a diagnostic. The unit will continue to run until you
replace the air filters.
Supply Air Static Pressure Limit
The opening of the VAV boxes coordinate during unit
startup and transition to/from occupied/unoccupied
modes to prevent supply air duct over pressurization.
However, if for any reason the supply air pressure exceeds
the supply air static pressure limit, the supply fan VFD
shuts down and a manual reset diagnostic is set.
Figure 39.
Basic water piping, constant water flow
Condenser 2
Condenser 3
Condenser 4
Condenser 3
Condenser 4
Condenser 2
WSE
Condenser 1
Condenser 1
Basic water piping, constant water flow
Basic water piping, constant water flow
with WSE
