Carrier SINGLE PACKAGE ROOFTOP UNITS 48PG20-28 - Manual (Page 19)

19
Condenser Fans and Motors — Condenser fans and
motors are factory set. Refer to Condenser-Fan Adjustment
section (page 49) as required.
Return-Air Filters — Check that correct filters are in-
stalled in filter tracks (see Table 1). Do not operate unit without
return-air filters.
NOTE: For units with 4-in. filter option, units are shipped with
standard 2-in. filters. To install 4-in. filters, the filter spacers
must be removed.
Outdoor-Air Inlet Screens — Outdoor-air inlet screens
must be in place before operating unit.
Gas Heat — Verify gas pressures before turning on heat as
follows:
1. Turn off field-supplied manual gas stop, located external
to unit.
2. Connect pressure gage to supply gas tap, located on field-
supplied manual shutoff valve (see Fig. 14).
3. Connect pressure gage to manifold pressure tap.
4. Turn on field-supplied manual gas stop. Temporarily
install the jumper wire between “R” and “W1” on TB2.
Set thermostat to HEAT and raise set point until heat
comes on.
5. After the unit has run for several minutes, verify the sup-
ply gas pressure is between 5.5 in. wg to 13.0 in. wg, and
the manifold pressure is 2.95 in. wg on horizontal dis-
charge applications and 3.00 on vertical discharge appli-
cations. If manifold pressure must be adjusted, refer to
Gas Valve Adjustment section.
NOTE: Supply gas pressure must not exceed 13.0 in. wg.
6. Set thermostat to OFF.
7. Remove jumper wire if the unit will be operating under
thermostat mode.
8. Return thermostat to desired set point.
Table 5 — Fan Performance — 48PGD20 Vertical Supply/Return Units
LEGEND
Boldface indicates field-supplied motor/drive required.
NOTES:
1. Motor drive ranges:
(A) Low Range: 685-939 rpm, 4.26 bhp (208/230 and 460-v), 751-954 rpm, 5.75 bhp (575-v)
(B) Mid-Low Range: 949-1206 rpm, 5.75 bhp
(C) Mid-High Range: 941-1176 rpm, 8.63 bhp
(D) High Range: 1014-1297 rpm, 11.50 bhp
All other rpms require field-supplied motor or drive.
2. See page 36 for general fan performance notes.
AIRFLOW
(Cfm)
AVAILABLE EXTERNAL STATIC PRESSURE (in. wg)
0.2 0.4 0.6 0.8 1.0
Rpm Bhp Rpm Bhp Rpm Bhp Rpm Bhp Rpm Bhp
5000 590 1.47 663 1.74 727 2.01 786 2.26 840 2.52
5500 633 1.82 703 2.11 764 2.40 820 2.67 872 2.94
6000 677 2.21 744 2.53 803 2.84 857 3.13 907 3.42
6500 722 2.67 786 3.01 842 3.33 894 3.64 942 3.95
7000 767 3.17 828 3.53 883 3.88 933 4.21 979 4.53
7500 813 3.74 871 4.12 924 4.48 972 4.83 1017 5.18
8000 859 4.36 915 4.77 966 5.15 1012 5.52 1056 5.88
8500 906 5.05 959 5.47 1008 5.87 1053 6.26 1096 6.64
9000 952 5.81 1004 6.25 1051 6.67 1095 7.07 1136 7.47
AIRFLOW
(Cfm)
AVAILABLE EXTERNAL STATIC PRESSURE (in. wg)
1.2 1.4 1.6 1.8 2.0
Rpm Bhp Rpm Bhp Rpm Bhp Rpm Bhp Rpm Bhp
5000 891 2.77 940 3.02 987 3.27 1032 3.52 1076 3.77
5500 921 3.21 968 3.48 1014 3.74 1057 4.01 1099 4.27
6000 954 3.70 999 3.99 1042 4.27 1084 4.55 1125 4.83
6500 988 4.25 1032 4.55 1073 4.85 1114 5.14 1153 5.44
7000 1024 4.85 1066 5.17 1106 5.48 1145 5.79 1183 6.10
7500 1060 5.51 1101 5.84 1140 6.17 1178 6.50 1215 6.82
8000 1098 6.23 1138 6.58 1176 6.92 1213 7.26 1249 7.60
8500 1137 7.01 1175 7.38 1212 7.74 1248 8.09 1283 8.45
9000 1176 7.86 1214 8.24 1250 8.61 1285 8.99 1319 9.36
Bhp — Brake Horsepower Input to Fan
A
B
C
D
B
B
B B
C
C
C
D
D
D
A
A
A A
A
B
B
B
B
C C
C C
C