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Although the 600 cfm, 700 cfm and 1200 cfm models have good efficiencies, the supply air could be colder than the ambient room air. It is possible to eliminate the
discomfort associated with this temperature difference by installing an electric duct heater. This will temper the air before it is distributed throughout the building.
The table below gives the heating requirements at different temperatures and airflows.
OUTDOOR AIR -40°F (- 40°C) OUTDOOR AIR -22°F (-30°C) OUTDOOR AIR -4°F (-20°C) OUTDOOR AIR +14°F (-10°C) OUTDOOR AIR +32°F (0°C)
Desired Air Temperature Desired Air Temperature Desired Air Temperature Desired Air Temperature Desired Air Temperature
55°F(13°C) 68°F(20°C) 73°F(23°C) 55°F(13°C) 68°F(20°C) 73
°F(
23°C
) 55°F(13°C) 68°F(20°C) 73°F(23°C) 55°F(13°C) 68°F(20°C) 73°F(23°C) 55°F(13°C) 68°F(20°C) 73°F(23°C)
kW kW kW kW kW kW kW kW kW kW kW kW kW kW kW
1250 590 14.6 19.9 21.9 11.2 16.5 18.5 7.8 13.1 15.2 4.4 9.7 11.8 1.0 6.3 8.4
1200 566 13.5 18.6 20.6 10.4 15.5 17.4 7.2 12.3 14.3 4.0 9.1 11.1 0.8 5.9 7.9
1150 542 12.6 17.4 19.3 9.6 14.5 16.4 6.6 11.5 13.4 3.6 8.5 10.4 0.7 5.5 7.4
1100 519 11.2 15.9 17.7 8.5 13.2 15.0 5.8 10.5 12.3 3.1 7.7 9.6 0.4 5.0 6.8
1050 495 10.7 15.2 16.9 8.1 12.6 14.3 5.5 10.0 11.7 2.9 7.4 9.1 0.4 4.8 6.5
1000 472 9.9 14.1 15.7 7.4 11.7 13.3 5.0 9.3 10.9 2.6 6.9 8.5 0.2 4.4 6.1
900 425 8.5 12.4 13.8 6.4 10.2 11.7 4.3 8.1 9.6 2.2 6.0 7.5 0.1 3.9 5.4
800 377 7.0 10.4 11.7 5.2 8.6 9.9 3.4 6.8 8.2 1.7 5.0 6.4 - 3.3 4.6
700 330 5.1 8.1 9.3 3.7 6.7 7.9 2.3 5.3 6.5 0.9 3.9 5.1 - 2.5 3.7
1200
CFM UNIT
Supply Air Supply Air
(cfm) (L/s)
OUTDOOR AIR -40°F (- 40°C) OUTDOOR AIR -22°F (-30°C) OUTDOOR AIR -4°F (-20°C) OUTDOOR AIR +14°F (-10°C) OUTDOOR AIR +32°F (0°C)
Desired Air Temperature Desired Air Temperature Desired Air Temperature Desired Air Temperature Desired Air Temperature
55°F(13°C) 68°F(20°C) 73°F(23°C) 55°F(13°C) 68°F(20°C) 73
°F(
23°C
) 55°F(13°C) 68°F(20°C) 73°F(23°C) 55°F(13°C) 68°F(20°C) 73°F(23°C) 55°F(13°C) 68°F(20°C) 73°F(23°C)
kW kW kW kW kW kW kW kW kW kW kW kW kW kW kW
700 330 7.4 10.4 11.5 5.6 8.6 9.7 3.9 6.8 8.0 2.1 5.1 6.2 0.3 3.3 4.4
650 307 6.6 9.4 10.5 5.0 7.8 8.9 3.4 6.2 7.3 1.8 4.6 5.6 0.2 3.0 4.0
600 283 5.9 8.5 9.4 4.5 7.0 8.0 3.0 5.6 6.5 1.6 4.1 5.1 0.1 2.7 3.7
550 259 5.2 7.6 8.5 3.9 6.3 7.2 2.6 5.0 5.9 1.3 3.7 4.6 0.1 2.4 3.3
500 236 4.0 6.1 7.0 3.0 5.1 5.9 1.9 4.0 4.9 0.9 3.0 3.8 - 1.9 2.7
450 212 3.0 4.9 5.6 2.1 4.0 4.8 1.3 3.2 3.9 0.4 2.3 3.1 - 1.5 2.2
400 189 2.2 3.9 4.6 1.5 3.2 3.9 0.9 2.5 3.2 0.2 1.9 2.5 - 1.2 1.8
600 and 700
CFM UNIT
Supply Air Supply Air
(cfm) (L/s)
NOTE:
The data does not reflect a reduction in effectiveness due to frosting. Based on the
standard air at: 1.2 Kg/m
3
and Cp = 1.0 KJ/Kg°C
13.35 lb/ft
3
and Cp = .24 Btu/lbm°F
Appendix G
Make-up Heat Requirements
1200 cfm
600 cfm and 700 cfm