035-20464-002 Rev. A (1004)
Unitary Products Group
23
Example: For a 130,000 BTUH (38.06 kW) furnace with 2 return open-
ings and operating on high-speed blower, it is found that total system
static is 0.58” w.c. To determine the system airflow, complete the follow-
ing steps:
Obtain the airflow values at 0.50 w.c. (125 Pa) & 0.60 w.c. (150 Pa)
ESP.
Airflow @ 0.50”: 2125 CFM (60.17 m
3
/min)
Airflow @ 0.60”: 2035 CFM (57.62 m
3
/min)
Subtract the airflow @ 0.50 w.c. (125 Pa) from the airflow @ 0.60 w.c.
(150 Pa) to obtain airflow difference.
2035 - 2125 = -90 CFM (2.55 m
3
/min)
Subtract the total system static from 0.50 w.c. (125 Pa) and divide this
difference by the difference in ESP values in the table, 0.60 w.c.
(150 Pa) - 0.50 w.c. (125 Pa), to obtain a percentage.
(0.58 - 0.50) / (0.60 - 0.50) = 0.8
Multiply percentage by airflow difference to obtain airflow reduction.
(0.8) X (-90) = -72
Subtract airflow reduction value to airflow @ 0.50 w.c. (125 Pa) to
obtain actual airflow @ 0.58 inwc (144 Pa) ESP.
2125 - 72 = 2053
NOTES
1. Airflow expressed in standard cubic feet per minute (CFM) and in cubic meters per minute (m
3
/min).
2. Motor voltage at 115 V.
* Input / CFM / Cabinet Width (A=14-1/2, B=17-1/2, C=21, D=24-1/2)
† Indicates model available in LoNOx.
TABLE 17:
Blower Performance CFM - Upflow (without filter) - Bottom Return
MODELS
Input /
CFM
Speed
Single Stage Bottom Airflow Data (SCFM)
Single Stage Bottom Airflow Data (cm/m)
Ext. Static Pressure (in. H2O)
Ext. Static Pressure (kPa)
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.025
0.050
0.075
0.100
0.125
0.149
0.174
0.199
0.224
0.249
40/1200/A
†
High
1610 1540 1460 1360 1290 1200 1110 1020 900 760 45.6 43.6 41.3 38.5 36.5 34.0 31.4 28.9 25.5 21.5
Medium
High 1430 1390 1330 1250 1190 1110 1030 940 840 710 40.5 39.4 37.7 35.4 33.7 31.4 29.2 26.6 23.8 20.1
Medium
Low 1200 1180 1140 1100 1050 1000 930 850 750 620 34.0 33.4 32.3 31.1 29.7 28.3 26.3 24.1 21.2 17.6
Low
980 980 960 920 890 840 790 720 620 530 27.8 27.8 27.2 26.1 25.2 23.8 22.4 20.4 17.6 15.0
60/1200/A
†
High
1570 1490 1420 1340 1250 1180 1090 990 870 700 44.5 42.2 40.2 37.9 35.4 33.4 30.9 28.0 24.6 19.8
Medium
High 1410 1360 1310 1250 1190 1090 1020 920 810 650 39.9 38.5 37.1 35.4 33.7 30.9 28.9 26.1 22.9 18.4
Medium
Low 1200 1180 1150 1100 1050 990 920 830 700 580 34.0 33.4 32.6 31.1 29.7 28.0 26.1 23.5 19.8 16.4
Low
960 960 950 930 900 840 800 720 610 500 27.2 27.2 26.9 26.3 25.5 23.8 22.7 20.4 17.3 14.2
80/1200/A
†
High
1590 1520 1460 1380 1300 1240 1150 1050 930 800 45.0 43.0 41.3 39.1 36.8 35.1 32.6 29.7 26.3 22.7
Medium
High 1400 1360 1310 1260 1200 1140 1070 960 860 740 39.6 38.5 37.1 35.7 34.0 32.3 30.3 27.2 24.4 21.0
Medium
Low 1180 1160 1130 1090 1040 990 920 840 750 640 33.4 32.8 32.0 30.9 29.4 28.0 26.1 23.8 21.2 18.1
Low
940 940 940 920 880 840 790 710 630 530 26.6 26.6 26.6 26.1 24.9 23.8 22.4 20.1 17.8 15.0
80/1600/B
†
High
1850 1820 1790 1750 1690 1630 1570 1500 1430 1330 52.4 51.5 50.7 49.6 47.9 46.2 44.5 42.5 40.5 37.7
Medium
1470 1450 1440 1430 1390 1360 1310 1270 1220 1150 41.6 41.1 40.8 40.5 39.4 38.5 37.1 36.0 34.5 32.6
Low
1260 1260 1260 1260 1250 1200 1150 1110 1070 1010 35.7 35.7 35.7 35.7 35.4 34.0 32.6 31.4 30.3 28.6
80/2200/C
†
High
2490 2410 2320 2230 2130 2030 1900 1790 1630 1470 70.5 68.2 65.7 63.1 60.3 57.5 53.8 50.7 46.2 41.6
Medium High 2120 2060 2000 1970 1840 1730 1680 1570 1460 1260 60.0 58.3 56.6 55.8 52.1 49.0 47.6 44.5 41.3 35.7
Medium Low 1720 1700 1670 1620 1570 1500 1430 1310 1160 1000 48.7 48.1 47.3 45.9 44.5 42.5 40.5 37.1 32.8 28.3
Low
1410 1390 1360 1330 1280 1220 1170 1060 930 840 39.9 39.4 38.5 37.7 36.2 34.5 33.1 30.0 26.3 23.8
100/1200/B
†
High
1700 1620 1560 1480 1390 1300 1210 1110 970 820 48.1 45.9 44.2 41.9 39.4 36.8 34.3 31.4 27.5 23.2
Medium
High 1430 1400 1350 1300 1230 1160 1080 980 870 710 40.5 39.6 38.2 36.8 34.8 32.8 30.6 27.8 24.6 20.1
Medium
Low 1180 1170 1160 1130 1080 1030 1000 860 750 510 33.4 33.1 32.8 32.0 30.6 29.2 28.3 24.4 21.2 14.4
Low
950 950 930 920 880 840 790 720 620 530 26.9 26.9 26.3 26.1 24.9 23.8 22.4 20.4 17.6 15.0
100/1600/B
†
High
1880 1850 1770 1720 1650 1560 1490 1420 1320 1210 53.2 52.4 50.1 48.7 46.7 44.2 42.2 40.2 37.4 34.3
Medium 1470 1460 1420 1390 1360 1300 1250 1190 1110 1000 41.6 41.3 40.2 39.4 38.5 36.8 35.4 33.7 31.4 28.3
Low
1250 1240 1220 1190 1150 1130 1070 1030 970 880 35.4 35.1 34.5 33.7 32.6 32.0 30.3 29.2 27.5 24.9
100/2000/C
†
High
2590 2500 2400 2280 2180 2080 1970 1840 1720 1560 73.3 70.8 68.0 64.6 61.7 58.9 55.8 52.1 48.7 44.2
Medium High 2180 2120 2040 1980 1900 1810 1720 1600 1480 1320 61.7 60.0 57.8 56.1 53.8 51.3 48.7 45.3 41.9 37.4
Medium Low 1750 1720 1680 1640 1580 1520 1440 1350 1220 1060 49.6 48.7 47.6 46.4 44.7 43.0 40.8 38.2 34.5 30.0
Low
1450 1420 1380 1330 1300 1240 1160 1070 970 860 41.1 40.2 39.1 37.7 36.8 35.1 32.8 30.3 27.5 24.4
115/1600/C
High
2020 1930 1820 1730 1640 1540 1400 1250 1090 920
57.2 54.7 51.5 49.0 46.4 43.6 39.6 35.4 30.9 26.1
Medium 1750 1710 1650 1590 1490 1390 1290 1160 1010 810 49.6 48.4 46.7 45.0 42.2 39.4 36.5 32.8 28.6 22.9
Low
1540 1500 1460 1410 1350 1260 1180 1060 910 750 43.6 42.5 41.3 39.9 38.2 35.7 33.4 30.0 25.8 21.2
115/2000/C
†
High
2500 2400 2320 2220 2110 2000 1870 1750 1610 1450 70.8 68.0 65.7 62.9 59.7 56.6 53.0 49.6 45.6 41.1
Medium High 2130 2070 1990 1920 1840 1760 1660 1570 1460 1320 60.3 58.6 56.4 54.4 52.1 49.8 47.0 44.5 41.3 37.4
Medium Low 1700 1680 1650 1620 1560 1500 1410 1320 1210 1070 48.1 47.6 46.7 45.9 44.2 42.5 39.9 37.4 34.3 30.3
Low
1420 1390 1360 1330 1290 1240 1150 1060 950 840 40.2 39.4 38.5 37.7 36.5 35.1 32.6 30.0 26.9 23.8
130/2000/D
†
High
2640 2550 2440 2340 2230 2110 2010 1870 1750 1580 74.8 72.2 69.1 66.3 63.1 59.7 56.9 53.0 49.6 44.7
Medium High 2120 2070 2010 1950 1890 1810 1730 1610 1490 1320 60.0 58.6 56.9 55.2 53.5 51.3 49.0 45.6 42.2 37.4
Medium Low 1690 1660 1640 1600 1550 1490 1410 1330 1240 1100 47.9 47.0 46.4 45.3 43.9 42.2 39.9 37.7 35.1 31.1
Low
1370 1360 1340 1310 1270 1230 1150 1070 990 850 38.8 38.5 37.9 37.1 36.0 34.8 32.6 30.3 28.0 24.1
