American Standard YK-IOM-2, Installation Operation & Maintenance

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Important: kW (BHP) listed in the Table is the
percentage range of nameplate amperage the motors
will safely work within before an oversized motor is
required.
3. Adjust the variable pitch pulley to increase or decrease the
fan RPM as required. See Figure 9.
Figure 9
Typical fan, motor, and sheave assembly
TO INCREASE m3/h (CFM)
Loosen the pulley adjustment set screw and turn sheave
clockwise
TO DECREASE m3/h (CFM)
Loosen the pulley adjustment set screw and turn sheave
counter-clockwise
TO INCREASE BELT TENSION
Loosen the nut (next to the idler sheave) that secures the
sheave in place. With a wrench, apply pressure clockwise on
the outside nut (round headed one), until tension desired is
reached. While holding pressure with the tension nut, retighten
the nut next to the idler sheave.
Electrical Connections
Electrical wiring and grounding must be installed in accor-
dance with national and local codes.
Electrical Power
It is important that proper electrical power is available for the
unit. Voltage variation should remain within the limits stamped
on the nameplate.
Power Entry
Holes are provided for low-voltage and high-voltage wiring. It
is not necessary to punch any new holes in either the interior
or exterior unit panels. If new holes are punched, performance
will be adversely affected unless they are resealed to be both
air- and watertight.
Disconnect Switch
Provide an approved weather-proof disconnect either on the
side of unit or within close proximity.
Over Current Protection
The branch circuit feeding the unit must be protected in accor-
dance with national and local codes.
Power Wiring
The power supply lines must be run in weather-tight conduit to
the disconnect, and into the bottom of the unit control box.
Provide strain relief for all conduit with suitable connectors.
IMPORTANT NOTE: Units with Scroll Compressors
only. Proper scroll compressor rotation is determined
by main power electrical connections. (See
Compressor Electrical Phasing section.)
Provide flexible conduit supports whenever vibration transmis-
sion may cause a noise problem within the building structure.
Insure all connections are made tight.
Note: For branch circuit wiring (main power supply
to unit disconnect), wire size for the length of run
should be determined using the circuit ampacity
found on the unit nameplate.
GROUNDING: THE UNIT MUST BE ELECTRICALLY
GROUNDED IN ACCORDANCE WITH NATIONAL AND LO-
CAL CODES.
Note: Unit must be grounded for igniter to operate
properly. Gas pipe to unit is not an adequate ground.
Ground the unit internally as provided. See unit
wiring diagram for location of grounding lug.
Control Wiring
Note about 24V Volt Transformers:
Units have intergal circuit breakers in their low voltage trans-
formers. If the breaker trips, be sure to open the unit discon-
nect before attempting to reset the breaker.
Open and lock unit
disconnect. Failure to do so could result in severe
personal injury or death due to electrical shock.
Remove compressor access panel and control box panel to
access transformer. Reset by pressing in on the black reset
button located on the left side of the transformer.
Replace all panels before restoring power to the unit.
Note: The unit 24 volt transformer must not be used
to power Field Installed Accessories (FIA), except for
the ones that are factory supported.