59SU5A: Installation, Start-up, Operating and Service Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
22
AIR DUCTS
General Requirements
The duct system should be designed and sized according to accepted
national standards such as those published by: Air Conditioning
Contractors Association (ACCA Manual D), Sheet Metal and Air
Conditioning Contractors National Association (SMACNA) or
American Society of Heating, Refrigerating and Air Conditioning
Engineers (ASHRAE) or consult The Air Systems Design Guidelines
reference tables available from your local distributor. The duct system
should be sized to handle the required system design CFM at the design
external static pressure. The furnace airflow rates are provided Table 11 -
CFM (with Filter). When a furnace is installed so that the supply ducts
carry air circulated by the furnace to areas outside the space containing
the furnace, the return air shall also be handled by duct(s) sealed to the
furnace casing and terminating outside the space containing the furnace.
Secure ductwork with proper fasteners for type of ductwork used. Seal
supply- and return-duct connections to furnace with code approved tape
or duct sealer.
NOTE: Flexible connections should be used between ductwork and
furnace to prevent transmission of vibration.
Ductwork passing through unconditioned space should be insulated to
enhance system performance. When air conditioning is used, a vapor
barrier is recommended.
Maintain a 1-in. (25 mm) clearance from combustible materials to
supply air ductwork for a distance of 36-in. (914 mm) horizontally from
the furnace. See NFPA 90B or local code for further requirements.
Return Duct Sizing
Refer to the Filter Selection and Duct Sizing section for information on
the proper selection of filter sizes and the associated ductwork and duct
transitions. Improperly designed filtering systems and return ductwork
are the most common causes of airflow and/or noise complaints in
HVAC systems.
NOTE:
1.A filter is required for each return-air inlet. Airflow performance includes a 3/4-in. (19 mm) washable filter media. See accessory list in Product Data Sheet. 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.
4.If the same motor speed tap is needed for heating and cooling, a Jumper Wire accessory kit is available, see Product Data Sheet 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.
Ductwork Acoustical Treatment
NOTE: Metal duct systems that do not have a 90 degree elbow and 10
ft. (3 M) of main duct to the first branch take-off may require internal
acoustical lining. As an alternative, fibrous ductwork may be used if
constructed and installed in accordance with the latest edition of
SMACNA construction standard on fibrous glass ducts. Both acoustical
NOTICE
!
Many states, provinces and localities are considering or have
implemented standards and/or restrictions on duct sizing practices,
ductwork leakage, and/or ductwork thermal, airflow and electrical
efficiencies. CONSULT LOCAL CODE OFFICIALS for ductwork
design and performance requirements in your area.
NOTICE
!
Cabinet air leakage is less than 2% at 1.0 in. w.c. Cabinet air leakage is
less than 1.4% at 0.5 in. w.c. when tested in accordance with ASHRAE
Standard 193.
Table 11 – Air Delivery - CFM (With Filter)
UNIT SIZE
WIRE LEAD
COLOR
SPEED TAP 2, 3
(function)
EXTERNAL STATIC PRESSURE (IN.W.C.)
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
040E17--12
Gray Cooling. Do not use for heating 1347 1312 1278 1244 1211 1177 1143 1110 1076 1043
Yellow Alt. Heating or Alt Cooling 1006 963 920 878 836 794 751 702 656 613
Blue Heating or Alt Cooling 860 811 763 716 668 613 560 513 472 430
Orange Alt. Heating or Alt Cooling 761 708 655 604 543 486 439 394 346 295
Red Alt. Cooling. Do not use for Heating 581 517 449 380 326 226 202 - - -
060E17--16
Gray Cooling. Do not use for Heating 1670 1635 1595 1555 1515 1475 1435 1395 1360 1315
Yellow Alt. Cooling. Do not use for Heating 1465 1420 1385 1345 1310 1265 1225 1180 1135 1095
Blue Heating or Alt. Cooling 1215 1170 1125 1085 1050 1005 965 925 880 830
Orange Alt. Heating or Alt. Cooling 1120 1065 1025 980 940 900 860 815 770 720
Red Alt. Cooling. Do not use for Heating 945 895 855 805 765 715 670 625 570 530
080E21--20
Gray
5, 6
Cooling. Do not use for Heating 2165 2135 2115 2070 2025 1980 1930 1885 1835 1790
Blue
5, 6
Heating or Alt. Cooling 1800 1755 1715 1670 1620 1575 1525 1475 1425 1380
Yellow Alt. Heating or Alt. Cooling 1645 1595 1550 1510 1460 1410 1365 1315 1265 1220
Orange Alt. Cooling. Do not use for Heating 1505 1450 1410 1360 1310 1265 1215 1170 1120 1080
Red
7
Alt. Cooling. Do not use for Heating 885 785 705 645 570 495 430 360 295 -
100E21--20
Gray
5, 6
Cooling Do not use for Heating 2215 2180 2140 2100 2065 2035 1995 1960 1925 1890
Blue
5, 6
Heating or Alt Cooling 1890 1850 1810 1770 1730 1690 1650 1610 1565 1520
Yellow Alt Cooling. Do not use for Heating 1695 1650 1605 1560 1515 1475 1425 1380 1325 1280
Orange Alt Cooling. Do not use for Heating 1270 1215 1155 1100 1040 980 925 865 810 765
Red
7
Alt Cooling. Do not use for Heating 800 715 630 550 475 390 320 - - -
100E21--22
Gray
5, 6
Cooling Do not use for Heating 2185 2145 2110 2070 2025 1985 1950 1915 1880 1840
Blue
5, 6
Heating or Alt Cooling 1910 1865 1820 1775 1730 1690 1645 1595 1545 1500
Yellow Alt Cooling. Do not use for Heating 1705 1655 1610 1560 1510 1460 1400 1345 1295 1245
Orange Alt Cooling. Do not use for Heating 1495 1440 1385 1330 1270 1205 1145 1090 1030 970
Red
7
Alt Cooling. Do not use for Heating 845 745 655 560 445 - - - - -
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