16
I-RX-RG-RPV (04-21) 1027501-A
INSTALLATION—CONTINUED
Duct Furnace Airflow Requirements
The duct furnace must be installed on the positive pressure side of the field-supplied blower. Air throughput must
be within the CFM range stated on the heater rating plate. The air distribution must be even over the entire heat
exchanger. To determine temperature rise, the inlet and outlet air temperatures should be measured at points not
affected by heat radiating from the heat exchanger. Refer to the Temperature Rise, CFM, and Pressure Drop
section for the approved temperature rise range with the required CFM and the internal pressure drop for each size
of unit. Refer to the Duct Furnace Blower Connections section for suggested blower connections that include
turning vanes used in elbows or turns in the air inlet to ensure proper air distribution. If it is determined that the blower
CFM is greater than that which is allowed or desirable, refer to the Bypass Duct Sizing section for instructions on
determining the correct size of bypass duct required.
Temperature Rise, CFM, and Pressure Drop
Table 11. Temperature Rise, CFM, and Pressure Drop
Temp
Rise
Unit Size
75 100 125 150 175 200 225 250 300 350 400
CFM
PD*
CFM
PD*
CFM
PD*
CFM
PD*
CFM
PD*
CFM
PD*
CFM
PD*
CFM
PD*
CFM
PD*
CFM
PD*
CFM
PD*
Model Series RPV (80% Thermal Efficient)
50°F
—
1840 0.50 2210 0.38 2580 0.52 2945 0.42 3315 0.53 3685 0.40 4420 0.58 5160 0.65 5895 0.67
60°F
1535 0.33 1840 0.26 2150 0.35 2455 0.28 2765 0.36 3070 0.28 3685 0.39 4300 0.44 4915 0.45
70°F
1315 0.25 1580 0.19 1840 0.26 2105 0.22 2370 0.27 2630 0.23 3160 0.29 3685 0.31 4210 0.32
80°F
1150 0.21 1380 0.15 1610 0.19 1840 0.17 2070 0.22 2300 0.22 2765 0.25 3225 0.25 3685 0.25
90°F
1020 0.18 1225 0.12 1430 0.16 1635 0.14 1840 0.17 2045 0.21 2455 0.22 2865 0.23 3275 0.19
Models HRP and HRPV (80% Thermal Efficient, High CFM)
20°F
—
4605 1.16 5530 0.85 6450 1.19 7370 1.00 8295 1.28 9215 0.90 11,060 1.26 12,900 1.23 14,745 1.23
30°F
3070 0.53 3685 0.39 4300 0.54 4915 0.45 5530 0.58 6140 0.41 7370 0.57 8600 0.56 9830 0.56
40°F
2300 0.28 2765 0.21 3225 0.29 3685 0.25 4145 0.31 4605 0.22 5530 0.32 6450 0.31 7370 0.31
50°F
1840 0.21 2210 0.15 2580 0.18 2945 0.16 3315 0.21 3685 0.15 4420 0.21 5160 0.19 5895 0.19
60°F
1535 0.15 1840 0.12 2150 0.15 2455 0.12 2765 0.15 3070 0.11 3685 0.15 4300 0.14 4915 0.15
75°F
1225 0.12 1475 0.11 1720 0.12 1965 0.11 2210 0.12 2455 0.08 2945 0.11 3440 0.11 3930 0.11
Models Series RG and RX (78% Thermal Efficient)
50°F
1075 0.22 1435 0.41 1795 0.47 2155 0.36 2515 0.49 2875 0.4 3235 0.50 3590 0.38 4310 0.55 5030 0.62 5750 0.64
60°F 895 0.14 1195 0.28 1495 0.32 1495 0.25 2095 0.33 2395 0.27 2695 0.34 2995 0.27 3590 0.37 4190 0.42 4790 0.43
70°F 770 0.09 1025 0.19 1280 0.24 1540 0.18 1795 0.25 2050 0.22 2310 0.26 2565 0.22 3080 0.28 3590 0.3 4105 0.31
80°F 670 0.06 895 0.14 1120 0.19 1345 0.14 1570 0.18 1795 0.16 2020 0.21 2245 0.21 2695 0.24 3145 0.24 3590 0.24
90°F 595 0.04 795 0.10 995 0.17 1195 0.11 1395 0.15 1595 0.13 1795 0.16 1995 0.19 2395 0.21 2795 0.22 3195 0.18
Models HRG and HRX (78% Thermal Efficient, High CFM)**
20°F 2695 0.58 3590 1.03 4490 1.10 5390 0.81 6290 1.13 7185 0.95 8085 1.22 8985 0.85 10,780 1.20 12,580 1.17 14,375 1.17
30°F 1795 0.27 2395 0.47 2995 0.50 3590 0.37 4190 0.51 4790 0.43 5390 0.55 5990 0.39 7185 0.54 8385 0.53 9585 0.53
40°F 1345 0.15 1795 0.27 2245 0.27 2695 0.19 3145 0.28 3590 0.24 4040 0.30 4490 0.21 5390 0.31 6290 0.30 7185 0.30
50°F 1075 0.11 1435 0.15 1795 0.19 2155 0.14 2515 0.17 2875 0.15 3235 0.19 3590 0.14 4310 0.19 5030 0.18 5750 0.18
60°F 895 0.09 1195 0.13 1495 0.14 1795 0.11 2095 0.14 2395 0.11 2695 0.14 2995 0.10 3590 0.14 4190 0.13 4790 0.14
75°F 715 0.09 955 0.11 1195 0.11 1435 0.10 1675 0.11 1915 0.10 2155 0.11 2395 0.07 2875 0.10 3355 0.10 3830 0.10
Model CRG and CRX (80% Thermal Efficient)
50°F
1110 0.24 1330 0.34 1655 0.39
—
2220 0.38
—
2960 0.41 3330 0.32 4000 0.47 4665 0.51 5330 0.53
60°F
920 0.15 1105 0.23 1375 0.26 1845 0.26 2460 0.28 2765 0.24 3320 0.32 3875 0.35 4430 0.36
70°F
752 0.10 945 0.16 1175 0.22 1575 0.19 2105 0.22 2365 0.20 2840 0.25 3315 0.26 3785 0.26
80°F
695 0.08 835 0.12 1040 0.18 1395 0.15 1860 0.17 2090 0.20 2510 0.22 2930 0.22 3345 0.21
85°F
650 0.08 780 0.12 975 0.17 1305 0.15 1740 0.16 1960 0.20 2350 0.21 2745 0.20 3135 0.18
Models (H)-CRG and (H)-CRX (80% Thermal Efficient, High CFM)
20°F
2775 0.60 3330 0.89 4145 0.92
—
5555 0.84
—
7405 1.03 8330 0.74 10,000 1.00 11,665 1.03 13,330 1.03
30°F
1875 0.28 2250 0.40 2800 0.41 3750 0.37 5000 0.45 5625 0.33 6750 0.47 7875 0.45 9000 0.45
40°F
1395 0.16 1670 0.22 2080 0.23 2790 0.21 3720 0.24 4185 0.19 5020 0.27 5860 0.26 6695 0.26
50°F
1110 0.13 1330 0.15 1655 0.16 2220 0.15 2960 0.16 3330 0.13 4000 0.17 4665 0.16 5330 0.17
60°F
920 0.11 1105 0.13 1375 0.13 1845 0.13 2460 0.13 2765 0.10 3320 0.13 3875 0.11 4430 0.13
70°F
790 0.10 950 0.11 1185 0.11 1585 0.11 2115 0.10 2380 0.08 2855 0.10 3330 0.10 3805 0.09
*PD = internal pressure drop (IN WC).
**Temperature rise for models approved to Canadian standards is 20°F–50°F.