York D*SC360, Руководство по установке

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2. Install two 1/4" O.D. tubes, one between the filters and the
air entering side of the evaporator coil and one between the
supply air blower(s) and the air leaving side of the evapo-
rator coil.
NOTE: To get a proper static pressure reading, the sensing
tubes should (A) be inserted through the rear or con-
densate drain side of the unit, (B) be located approxi-
mately 6 inches away from the coil surface and as
close to the center of the coil height as possible, (C)
extend into the unit approximately 12 inches.
3. Make sure that the access panels for both the supply air
blower motor and the filters are partially secured. These
panels do not have to be secured where the 1/4" tubes enter
the units because the blower and filter compartments
operate at a negative pressure.
4. Make sure that the tube openings are perpendicular to the
air flow so that velocity pressure will not affect the static
pressure readings.
CAUTION: If this method is used, the holes must be sealed
with dot plugs (P/N 029-13880) or equivalent to
prevent moisture from leaking into the unit.
5. Using an inclined manometer, determine the pressure drop
across a dry evaporator coil. Since the moisture on an
evaporator coil may vary greatly, measuring the pressure
drop across a wet coil under field conditions would be
inaccurate.
NOTE: Disconnect the compressors before taking any test
measurements to assure a dry evaporator coil.
6. Knowing the pressure drop across a dry coil, the actual
CFM through the unit can be determined from the curve in
Figure18.
If the CFM is above or below the specified value, the supply air
motor pulley may have to be readjusted. After one hour of
operation, check all belts and pulleys for tightness and align-
ment.
WARNING: Failure to properly adjust the total system CFM can
result in extensive blower damage
FIG. 17 - HOLE LOCATIONS FOR SUPPLY AIR
CFM CHECK
FIG. 18 - PRESSURE DROP ACROSS A DRY
EVAPORATOR COIL VS SUPPLY AIR CFM
MODEL
% OF NOMINAL CFM
80 90 100 110 120
CFM
DSC360 9600 10800 12000 13200 14400
DSC480 12800 14400 16000 17600 19200
MASTER PRINTED CIRCUIT BOARD & PLUG-IN
RELAY ASSEMBLY
All of the control relays that are required for unit operation are
mounted on the printed circuit board. Figure 9, 10, 11 or 12
shows this assembly which is located in the main control panel.
All of the relays are of the plug-in variety; no wiring connections
have to be removed to replace a relay. Since the relays are
transparent, the mechanical contact switching can be observed
for easier electrical troubleshooting.
The low voltage field wiring is to be connected along the top of
the printed circuit board at the eyelet connections. Each terminal
is marked both numerically and with letters corresponding to the
room thermostat for easier installation.
Two jumper plugs, one red and one white, are located at the top
of the board. When they are removed and replaced with the
connectors of the service analyzer, the analyzer will override the
room thermostat. All system functions such as heating, cooling,
economizer, and night set-back can be simulated. Malfunction
indicator lights are provided to determine which system has
malfunctioned.
CAUTION: When removing the connectors of the service ana-
lyzer, the two jumper plugs (one red and one white)
must be reinstalled into their proper sockets before
the system can function.
The following procedure is an outline for troubleshooting a unit
with a service analyzer connected to its printed circuit board.
530.25-N3Y
18 Unitary Products Group