Phasing; Checking Supply Air Cfm; Air Balance; Belt Adjustment - York DW-15 Installation Manual

PHASING

UPG MODEL DW, units are properly phased at the fac-
tory. Check for proper compressor rotation. If the
blower or compressors rotate in the wrong direction at
start-up, the electrical connection to the unit is mis-
phased. Change the incoming line connection phasing
to obtain proper rotation. (Scroll compressors operate
in only one direction. If the scroll is drawing low amper-
age, has similar suction and discharge pressures, or
producing a high noise level, the scroll is misphased).
Scroll compressors require proper rotation to
operate correctly. Units are properly phased at
the factory. Do not change the internal wiring to
make the blower, condenser fans, or compres-
sor rotate correctly.

CHECKING SUPPLY AIR CFM

The RPM of the supply air blower will depend on the
required CFM, the unit accessories or options and the
static resistances of both the supply and the return air
duct systems. With this information, the RPM for the
supply air blower and the motor pulley adjustment
(turns open) can be determined from the Blower Per-
formance Data Tables.
High speed drive accessories (containing a smaller
blower pulley and a shorter belt) are available for appli-
cations requiring the supply air blower to produce
higher CFM's and/or higher static pressures. Use
Model 1LD0460 for 15 ton units, Model 1LD0417 for
17.5 and 20 ton units, and Model 1LD0435 for 25 ton
units. Refer to the Blower Motor and Drive Data
Table 21.
Note the following:
1. The supply air CFM must be within the limitations
shown in the Unit Application Data Table 1.
2. Pulleys can be adjusted in half turn increments.
3. The tension on the belt should be adjusted as
shown in the Belt Adjustment Figure 21.
44
FIGURE 21 - BELT ADJUSTMENT

AIR BALANCE

On VAV units be certain that the VFD drive is
set to maximum output, exhaust dampers are
closed and individual space damper boxes are
full open.
VFD units with bypass must not be in bypass
mode ('LINE' position) unless all individual
space dampers are full open.
Start the supply air blower motor. Adjust the resis-
tances in both the supply and the return air duct sys-
tems to balance the air distribution throughout the
conditioned space. The job specifications may require
that this balancing be done by someone other than the
equipment installer.
To check the supply air CFM after the initial balancing
has been completed:
1. Remove the two 5/16" dot plugs from the blower
motor and the filter access panels shown in the
Dimensions and Clearances Figure 13.
284816-BIM-B-0707
Unitary Products Group