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912SD: Installation, Start-up, Operating and Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
54
See NOTES following table.
1. A filter is required for each return-air inlet. Airflow performance includes a 3/4-in. (19 mm) washable filter media such as contained in a factory-authorized filter rack. See accessory list
in Product Data. To determine airflow performance without this filter, assume an additional 0.1 in. w.c. available external static pressure.
2. ADJUST THE BLOWER SPEED TAPS AS NECESSARY FOR THE PROPER AIR TEMPERATURE RISE FOR EACH INSTALLATION.
3. The “Function” column identifies which speed taps can be used for heating. Shaded areas indicate that this airflow range is
BELOW THE RANGE ALLOWED FOR HEATING
OPERATION. THESE AIRFLOW RANGES MAY ONLY BE USED FOR COOLING.
4. If the same motor speed tap is needed for heating and cooling, a Jumper Wire accessory kit is available, see Product Data for the current Jumper Wire accessory part number.
Reference the “Start-up, Adjustments, and Safety Check” section for further Jumper Wire instructions.
5. Airflows over 1800 CFM require bottom return, two-side return, or bottom and side return. A minimum filter size of 20” x 25” (508 x 635 mm) is required.
6. For upflow applications, air entering from one side into both the side of the furnace and a return air base counts as a side and bottom return.
7. The “-” entry indicates an unstable operating condition.
Adjust Cooling Airflow
The cooling airflow can be set from the remaining blower speed taps.
Refer to the Air Delivery Tables in these instructions.
If the same motor speed tap is needed for heating and cooling, a Jumper
Wire accessory kit is available, see Product Data for the current Jumper
Wire accessory part number. The single wire end of the jumper will be
connected to the desired blower motor speed lead. The two wire end of
the jumper will be connected to the control board, connecting one wire
to the HEAT (heating blower tap) terminal and the other will be
connected to the COOL (cooling blower tap). Use the provided wire ties
to secure the loose blower motor speed lead and any other loose wires,
being careful not to put tension on any wire connectors.
Adjust Thermostat Heat Anticipator
Mechanical thermostat
: Set thermostat heat anticipator to match the
amp draw of the electrical components in the R-W circuit. Accurate amp
draw readings can be obtained at the wires normally connected to
thermostat subbase terminals R and W. The thermostat anticipator
should NOT be in the circuit while measuring current.
1. Remove thermostat from subbase or from wall.
2. Connect an amp meter across the R and W subbase terminals or R
3. Record amp draw across terminals when furnace is in low heat and
after blower starts.
4. Set heat anticipator on thermostat per thermostat instructions and
install on subbase or wall.
5. Install blower access door.
Electronic thermostat
: Set cycle rate for 3 cycles per hr.
A96316
Fig. 65 – Amp. Draw Check with Ammeter
60080E21
Gray
5,
6
Cooling. Do not use for heating
2020 1965 1920 1865 1815 1760 1705 1650 1595 1545
Yellow
Alt Cooling or alt Heating
1650 1590 1535 1475 1425 1370 1315 1260 1205 1145
Blue
Heating or alt Cooling
1495 1430 1365 1310 1260 1200 1145 1085 1030 970
Orange
Alt Cooling or alt Heating
1420 1355 1290 1235 1175 1120 1060 1005 945
890
Red
3
Alt Cooling. Do not use for heating
1200 1120 1060 995
940
875
810
750
685
625
60100E21
Gray
5, 6
Cooling. Do not use for heating
2060 2010 1955 1905 1850 1800 1750 1690 1630 1565
Blue
Heating or alt Cooling
1730 1675 1620 1565 1510 1455 1385 1325 1270 1210
Yellow
Alt Cooling or alt Heating
1685 1630 1570 1515 1460 1410 1345 1280 1225 1170
Orange
3
Alt Cooling or alt Heating
1445 1370 1310 1250 1185 1115 1055 1005 950
875
Red
3
Alt Cooling. Do not use for heating
1235 1155 1090 1020 945
900
835
755
690
635
66100E21
Gray
5, 6
Cooling. Do not use for heating.
2205 2160 2120 2085 2045 2005 1965 1925 1885 1840
Yellow
5, 6
Alt Cooling. Do not use for heating.
2120 2080 2035 1995 1955 1915 1875 1830 1790 1745
Orange
Alt Cooling or alt Heating
1800 1755 1710 1665 1615 1570 1520 1470 1420 1375
Blue
Heating or alt Cooling
1680 1630 1580 1535 1485 1435 1380 1330 1275 1225
Red
3
Alt Cooling or alt Heating
1500 1445 1390 1340 1285 1225 1170 1110 1055 1000
60120E24
Gray
5, 6
Cooling. Do not use for heating
2070 2020 1965 1910 1850 1790 1725 1660 1605 1550
Blue
Heating or alt Cooling
1795 1735 1680 1620 1560 1495 1440 1375 1315 1255
Yellow
3
Alt Cooling or alt Heating
1465 1400 1340 1270 1210 1150 1090 1030 950
880
Orange
3
Alt Cooling. Do not use for heating
1295 1235 1165 1095 1030 970
905
825
760
700
Red
3
Alt Cooling. Do not use for heating
1095 1020 945
875
805
730
660
585
525
465
Table 21 – Air Delivery - CFM (With Filter) (Continued)
FURNACE
SIZE
SPEED
TAPS
Function
EXTERNAL STATIC PRESSURE (IN.W.C.)
0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in personal injury, death,
and/or property damage.
Reinstall manifold pressure tap plug in gas valve to prevent gas leak.
CAUTION
!
FURNACE OVERHEATING HAZARD
Failure to follow this caution may result in reduced furnace life.
Recheck temperature rise. It must be within limits specified on the
rating plate. Recommended operation is at the mid-point of rise range
or slightly above.
R
Y W
G
10 TURNS
THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED
(ANITICIPATOR, CLOCK, ETC.,
MUST BE OUT OF CIRCUIT.)
HOOK-AROUND
AMMETER
EXAMPLE:
5.0 AMPS ON AMMETER
10 TURNS AROUND JAWS
=
0.5 AMPS FOR THERMOSTAT
ANTICIPATOR SETTING
FROM UNIT 24-V
CONTROL TERMINALS