Thermo Products CMA2-75N, CMA1-50N service manual D. Closet Installation, Figure

All installations and services must be performed by qualified service personnel.

D. CLOSET INSTALLATION

1.The return air opening into the closet is to have a minimum free area of 250

sq. in. (see Figure 5).

2. The return air opening may be

located in the top, center or (ideally) bottom of the closet door or side wall.

Figure 5.

: Do not obstruct any return air openings, including the return grille on the furnace. To do so may cause the furnace to activate the high limit and shut down.

3.The cross-sectional area of the return system leading into the closet (when located in the floor or ceiling) shall not be less than 250 square inches.

4.The total free area of openings in the floor or ceiling registers serving the return duct system must be at least 350 square inches. At least one register must be located where it is not likely to be covered by carpeting, boxes, furniture or other objects.

5.Materials located in the return duct system must have a flame spread classification of 200 or less.

6.Non-combustible pans having one inch upturned flanges are to be located beneath openings in a floor return duct system.

7.Wiring materials located in the return duct system must conform to articles 300-22 of the National Electrical Code NFPA70 (Latest Edition).

8.Gas piping is not to be located in or through the return duct system .

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