1. Two additional 7/8 ---in. (22 mm) diameter holes are located in the top plate.
2. Minimum return ---air openings at furnace, based on metal duct. If flex duct is used, see flex duct manufacturer's recommendations for equivalent diameters.
a. For 800 CFM ---16 ---in. (406 mm) round or 14 1/2 x 12 ---in. (368 x 305 mm) rectangle.
b. For 1200 CFM ---20 ---in. (508 mm) round or 14 1/2 x 19 1/2 ---in. (368 x 495 mm) rectangle.
c. For 1600 CFM ---22 ---in. (559 mm) round or 14 1/2 x 22 1/16 ---in. (368 x 560mm) rectangle.
d. For airflow requirements above 1800 CFM, see Air Delivery table in Product Data literature for specific use of single side inlets. The use of both side inlets,
a combination of 1 side and the bottom, or the bottom only will ensure adequate return air openings for airflow requirements above 1800 CFM.
A
FURNACE
CABINET
SIZE
WIDTH
045--- 12
14-3/16 (360)
070--- 16
17--- 1/2 (445)
090--- 16
21 (533)
110--- 22
21 (533)
135--- 22
24-1/2 (622)
*135 size furnaces require a 5 or 6 ---in. (127 or 152 mm) vent. Use a vent adapter between furnace and vent stack. See Installation Instructions for complete