York 120 User Manual
035-17311-002-A-0803
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.
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 10).
the dot plugs see Figure 10).
2.
Insert eight-inches of 1/4 inch metal tubing into the air-
flow on both sides of the indoor coil.
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.
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.
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.
measurements to assure a dry evaporator coil.
4.
The CFM through the unit can be determined from the
pressure drop indicated by the manometer by referring to
Figure 23. In order to obtain an accurate measurement,
be certain that the air filters are clean.
pressure drop indicated by the manometer by referring to
Figure 23. In order to obtain an accurate measurement,
be certain that the air filters are clean.
5.
To adjust Measured CFM to Required CFM, see ’SUP-
PLY AIR DRIVE ADJUSTMENT’.
PLY AIR DRIVE ADJUSTMENT’.
6.
After readings have been obtained, remove the tubes
and replace the dot plugs.
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.
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.
Using the whole drilled in step 1, insert eight inches of
1/4 inch metal tubing into the airflow of the return and
supply air ducts of the unit.
1/4 inch metal tubing into the airflow of the 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.
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). In order to obtain an accurate
measurement, be certain that the air filters are clean.
the pressure drop across the unit. This is the External
Static Pressure (ESP). In order to obtain an accurate
measurement, be certain that the air filters are clean.
4.
Determine the number of turns the variable motor
sheave is open.
sheave is open.
5.
Select the correct blower performance table for the unit
from Tables 17 - 28. Tables are presented for horizontal
and downflow configuration.
from Tables 17 - 28. Tables are presented for horizontal
and downflow configuration.
6.
Determine the unit Measured CFM from the Blower Per-
formance Table, External Static Pressure and the num-
ber of turns the variable motor sheave is open.
formance Table, External Static Pressure and the num-
ber of turns the variable motor sheave is open.
7.
To adjust Measured CFM to Required CFM, see ’SUP-
PLY AIR DRIVE ADJUSTMENT’.
PLY AIR DRIVE ADJUSTMENT’.
8.
After reading has been obtained, remove the tubes and
seal holes.
seal holes.
NOTE:
With the addition of field installed accessories
repeat this procedure.
repeat this procedure.
TABLE 29: 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
DM090
1-1/2
1725
80%
1.15
56
3.4 - 4.4
7/8
1VM50
9.0
1
AK94
A57
2
1725
80%
1.15
56
3.4 - 4.4
7/8
1VM50
7.5
1
AK79
A55
DM120
2
1725
80%
1.15
56
3.4 - 4.4
7/8
1VM50
8.5
1
AK89
A56
3
1725
80%
1.15
56
3.4 - 4.4
7/8
1VM50
7.0
1
AK74
A54
DM150
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.
tity can result in extensive blower damage.
Failure to properly adjust the total system air quan-
tity can result in extensive blower damage.
tity can result in extensive blower damage.