York AHU, Operation And Maintenance

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JOHNSON CONTROLS
29
SECTION 2 - START-UP AND OPERATION
FORM 102.20-OM2
ISSUE DATE: 6/01/2015
2
Variable Frequency Drive (VFD)
Johnson Controls air modulators are,
unless otherwise selected, provided with
start-up service. See forms 100.41-NO1
and 100.42-NO1.
The VFD controlling the speed of the AHU fan(s) needs
to be set up properly so the fan does not run at resonant
frequencies. This is true whether the VFD is field or
factory mounted. An option is available when ordering
the AHU to select Inverter Drive Balance (Sweep Bal-
ance). When the option is selected, the factory provides
a document or label attached to the fan assembly that
lists any values that exceed the peak to peak tolerance.
See Figure 19 below. These values are referred to as
Skip Frequencies (Jump or Lockout Frequencies). The
technician performing start up of the VFD is to enter
these values in the VFD programming according to
the manufacturer’s instructions. This step will prevent
continuous operation at the resonant frequencies listed
on the label. If the option was not selected on the AHU
order, it is the customer’s responsibility to have the In-
verter Drive Balance (Sweep Balance) performed and
enter any detected Skip Frequencies (Jump or Lockout
Frequencies) in the VFD program. This should be done
during start up.
Failure to properly set up the VFD before
applying power to the motor will void the
fan and motor warranty.
FIGURE 19 - EXAMPLE OF SWEEP BALANCE
RESULTS LABEL ON FAN HOUSING
LD16564
Check Doors And Latches
Refer to the service manual for adjusting and replacing
the doors.
Solution XT doors are shipped with metal shipping
spacers glued onto the edges of each door. They are
located on three edges of each door (top, latch side &
bottom) ( Figure 20 on page 29) . The spacers should
be left in place until the AHU is placed in its final loca-
tion and multiple skid AHUs are fully assembled. After
AHU installation use a channel lock pliers or a screw-
driver to remove the spacers. Do not damage the metal
door panel. Slight impressions left on the door gasket
by the spacers will rebound in approximately a week.
FIGURE 20 - METAL SPACERS ON SOLUTION XT
DOORS
LD16574
Energy Recovery Wheel
Configuring the AHU
Indoor AHUs - All indoor AHUs will accommodate
vertical energy recovery wheel segments in a tiered
configuration as shown in
Figure 21 on page 29
.
Outdoor AHUs - All outdoor AHUs will accommo-
date horizontal energy recovery wheel segments in a
low-profile, single AHU arrangement as shown in Fig-
ure 22 on page 30
.
Keep hands away from rotating wheel!
Contact with the rotating wheel can cause
physical injury.
FIGURE 21 -
VERTICAL WHEEL FOR INDOOR AHU
LD16566
Filter
Return Air
Supply
Fan
Mixing
Box
Cooling
Coil
Energy
Wheel
Heating
Coil
Exhaust
Fan
Filter/
Mixing
Box
Outside
Air