5566217-JIM-C-1019
50 Johnson Controls Ducted Systems
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. See Figures 12
and 13.
2. Insert eight-inches of 1/4 inch metal tubing into the airflow
on both sides of the indoor coil.
Note: You must insert the tubes and hold them in a position
perpendicular to the air flow so that velocity pressure
does not affect the static pressure readings.
3. Use an inclined manometer or Magnehelic® to determine
the pressure drop across a dry evaporator coil. The
moisture on an evaporator coil can vary greatly, measuring
the pressure drop across a wet coil under field conditions
could be inaccurate. To ensure that the coil is dry, de-
activate the compressors de-activated while the test is
being run.
Note: De-energize the compressors before you take any test
measurements to ensure that the evaporator coil is dry.
4. Use the pressure drop indicated by the manometer and the
graph in Figure 31 to determine the unit CFM. In order to
obtain an accurate measurement, verify that the air filters
are clean.
5. To adjust measured CFM to required CFM, see Supply air
drive adjustment on page 52.
6. After you note the readings, remove the tubes and replace
the dot plugs.
7. Tighten the blower pulley and motor sheave set screws
after any adjustments. Re-check the set screws after 10-12
hours run time.
Table 20: Indoor blower specifications
Size
(tons)
Model
Motor Motor sheave Blower sheave
Belt
HP RPM Eff. SF Frame
Datum dia.
(in.)
Bore (in.) Model
Datum dia.
(in.)
Bore (in.) Model
J06
(6.5)
ZH
1-1/2 1725 0.8 1.15 56 3.4 - 4.4 7/8 1VM50 7.0 1 AK74 A49
2 1725 0.8 1.15 56 3.4 - 4.4 7/8 1VM50 6.0 1 AK64 A49
J07
(7.5)
ZH
1-1/2 1725 0.8 1.15 56 3.4 - 4.4 7/8 1VM50 7.0 1 AK74 A49
3 1725 0.8 1.15 56 3.4 - 4.4 7/8 1VM50 5.7 1 AK61 A49
J08
(8.5)
ZH
2 1725 0.8 1.15 56 3.4 - 4.4 7/8 1VM50 9.0 1 AK94 A56
3 1725 0.8 1.15 56 3.4 - 4.4 7/8 1VM50 7.0 1 AK74 A54
J10
(10)
ZH
2 1725 0.8 1.15 56 3.4 - 4.4 7/8 1VM50 8.0 1 AK84 A56
3 1725 0.8 1.15 56 3.4 - 4.4 7/8 1VM50 7.0 1 AK74 A54
J12
(12.5)
ZH
3 1725 0.8 1.15 56 3.4 - 4.4 7/8 1VM50 7.0 1 AK74 A54
5 1725 0.87 1.15 184T 4.3 - 5.3 1-1/8 1VP56 6.7 1 BK77 BX55
Table 21: Power exhaust specifications
Model Voltage
Motor Unit (per circuit)
Fuse size
CFM @
0.1 ESP
HP RPM
1
1. Motors are multi-tapped and factory wired for high speed.
QTY LRA FLA MCA
2PE04704706 208/230-1-60 3/4 1075 1 24.9 5 6.3 10 4800
2PE04704746 460-1-60 3/4 1075 1 N/A 2.2 2.8 5 4800
2PE04704758 575-1-60 3/4 1050 1 N/A 1.5 1.9 4 4800
On VAV units be certain that the VFD is set to maximum
output, exhaust dampers are closed and individual
space damper boxes are fully open.
VFD units with manual bypass option must not be in the
bypass mode (LINE position), unless all individual space
dampers are fully open.
You must adjust the belt drive blower systems to the
specific static and CFM requirements for the application.
The belt drive blowers are not set at the factory for any
specific static or CFM. You must adjust the blower speed
and belt tension.
Verify proper sheave alignment. Tighten the blower
pulley and motor sheave set screws after these
adjustments. Re-check the set screws after 10-12 hours
of run time.
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