York DJ150 - Manual (Page 31)

035-19046-002-B-0104
Unitary Products Group 31
AIR BALANCE
Start the supply air blower motor. Adjust the resistances in both the supply and the return air duct systems 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.
CHECKING AIR QUANTITY
METHOD ONE
1. Remove the dot plugs from the duct panel (for location of
the dot plugs see Figure 9).
2. Insert eight-inches of 1/4 inch metal tubing into the air-
flow on both sides of the indoor coil.
NOTE: The tubes must be inserted and held in a position
perpendicular to the air flow so that velocity pres-
sure will not affect the static pressure readings.
3. Use an Inclined Manometer or Magnehelic to determine
the pressure drop across a dry evaporator coil. Since the
moisture on an evaporator coil can vary greatly, measur-
ing the pressure drop across a wet coil under field condi-
tions could be inaccurate. To assure a dry coil, the
compressors should be de-activated while the test is
being run.
NOTE: De-energize the compressors before taking any test
measurements to assure a dry evaporator coil.
4. The CFM through the unit with clean 2 inch filters can be
determined from the pressure drop indicated by the
manometer by referring to Figure 25.
5. To adjust Measured CFM to Required CFM, see ’SUP-
PLY AIR DRIVE ADJUSTMENT’.
6. After adjustments have been completed, remove the
tubes and replace the dot plugs.
METHOD TWO
1. Drill two 5/16 inch holes, one in the return air duct as
close to the inlet of the unit as possible, and another in
the supply air duct as close to the outlet of the unit as
possible.
2. Insert eight inches of 1/4 inch metal tubing into the air-
flow of both return and supply air ducts of the unit.
NOTE: The tubes must be inserted and held in position per-
pendicular to the airflow so that velocity pressure
will not affect the static pressure readings.
3. Use an Inclined Manometer or Magnehelic to determine
the pressure drop across the unit. This is the External
Static Pressure (ESP).
4. Select the indoor blower specifications for the unit from
Table 19, 3 or 5 H.P. Motor.
5. Determine the number of turns the variable pitch motor
sheave is open.
6. Select the correct blower performance table for the unit
from Tables 15 - 18.
7. Determine the unit Measured CFM from the Blower Per-
formance Table, External Static Pressure and number of
turns the variable pitch motor sheave is open.
8. To adjust Measured CFM to Required CFM, see ’SUP-
PLY AIR DRIVE ADJUSTMENT’.
9. After adjustments have been completed, remove the
tubes and seal holes.
NOTE: With the addition of field installed accessories
repeat this procedure.
TABLE 19: INDOOR BLOWER SPECIFICATIONS
MODEL
MOTOR MOTOR SHEAVE BLOWER SHEAVE
BELT
HP RPM Eff. SF Frame Datum Dia. (in.) Bore (in.) Model Datum Dia. (in.) Bore (in.) Model
DJ150
3 1725 80% 1.15 56 3.4 - 4.4 7/8 1VM50 7.0 1 AK74 A54
5 1725 87% 1.15 184T 4.3 - 5.3 1 1/8 1VP56 6.7 1 BK77 BX55
Failure to properly adjust the total system air quan-
tity can result in extensive blower damage.
Failure to properly adjust the total system air quan-
tity can result in extensive blower damage.