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Operating Fan for Test and Balance
During the Test and Balance procedure, it is necessary to operate
the supply fan in High Speed without concurrent operation of the
Cooling or Heating systems. Use the following procedure to force
the fan speed to High.
UNIT WITH ACCESSORY VFD KEYPAD
1.
Set the space thermostat to SYSTEM OFF and FAN in
AUTO.
2.
Disconnect unit power. Lock-out/tag-out.
3.
Open the fan access panel (see Fig. 10-27 for specific unit).
4.
Locate pressure ports or pitot tubes in the return duct and sup-
ply duct to measure external static pressure. See Fig. 28 and
Tables 29-31 for typical locations.
5.
Restore unit power.
6.
Set the space thermostat to FAN CONT.
7.
At the VFD keypad, tap the HAND key and then tap the
UP arrow button to increase the motor speed until 60.0 is
displayed on the display screen.
8.
Check the motor speed with stroboscope or similar tool.
Motor shaft speed must be in 1725 to 1760 rpm
(28.8 to 29.3 r/s) range for High Speed.
9.
Replace the fan access panel.
10. Perform Test and Balance procedure.
11. Adjust the supply fan speed according to base unit instruc-
tions to deliver the project selection CFM value. Ensure
the selection CFM value is not lower that the "Min CFM
Per Fan Motor Type" for this unit-size as found in
Tables 4-28 on pages 7-10.
To restore the unit to ready-to-start condition, tap the DOWN
arrow button to reduce motor speed until the 40.0 is displayed on
the display screen and then tap the AUTO key. Disconnect the unit
power and lock-out/tag-out, set the space thermostat to FAN
AUTO. Remove the test pressure ports from the external duct lo-
cations. Restore unit power.
SUPPLY
AIR
A
Fig. 28 — Measuring External Static Pressure —
Distance Below Unit Base
RETURN
AIR
B
Table 29 — Measuring External Static Pressure —
Distance Below Unit Base — Carrier
AHRI PRESSURE LOCATIONS
Supply
MODEL
SIZES
07-12
48/50HC
14
17-28
07
08-14
48/50TC
16
17-30
04-06
50HCQ
07-09
12
04-07
08-12
50TCQ
14
17-24
Table 30 — Measuring External Static Pressure —
Distance Below Unit Base — Bryant
AHRI PRESSURE LOCATIONS
Supply
MODEL
SIZES
07-12
581J/551J
14
17-28
07
08-14
580J/558J
16
17-30
07-09
549J
12
07
08-12
548J
14
17-24
Table 31 — Measuring External Static Pressure —
Distance Below Unit Base — ICP
AHRI PRESSURE LOCATIONS
Supply
MODEL
SIZES
090-120
RGH/RAH
150
181-303
090-140
RGS/RAS
181-336
090-102
RHH
120
090-120
RHS
150
181-243
24
in.
in.
mm
Return
Supply
Air
Air
Air
[A]
[B]
[A]
43-1/2
12
1100
64-1/2
14
1640
83
19
2110
32
10
830
43-1/2
12
1100
64-1/2
14
1640
83
19
2110
32
10
1100
43-1/2
12
1100
44-1/2
13
1130
32
10
830
43-1/2
12
1100
44-1/2
14
1130
83
19
2110
in.
in.
mm
Return
Supply
Air
Air
Air
[A]
[B]
[A]
43-1/2
12
1100
64-1/2
14
1640
83
19
2110
32
10
830
43-1/2
12
1100
64-1/2
14
1640
83
19
2110
43-1/2
12
1100
44-1/2
13
1130
32
10
830
43-1/2
12
1100
44-1/2
14
1130
83
19
2110
in.
in.
mm
Return
Supply
Air
Air
Air
[A]
[B]
[A]
43-1/2
12
1100
64-1/2
14
1640
83
19
2110
43-1/2
12
1100
83
19
2110
43-1/2
12
1100
44-1/2
13
1130
43-1/2
12
1100
44-1/2
14
1130
83
19
2110
mm
Return
Air
[B]
310
350
490
260
310
350
490
310
310
330
260
310
350
490
mm
Return
Air
[B]
310
350
490
260
310
350
490
310
330
260
310
350
490
mm
Return
Air
[B]
310
350
490
310
490
310
330
310
350
490
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