Unitary products group GM8S*UH Installation Manual Download Page 7

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166753-UIM-C-0706

Unitary Products Group

This  appliance  is  design  certified  for  line  contact  when  the  furnace  is
installed  in  the  horizontal left  or  right position. The  line  contact  is  only
permissible between lines that are formed by the intersection of the top
and  two  sides of  the  furnace  and  the  building  joists,  studs  or  framing.
This line may be in contact with combustible material. Refer to Figure 3.

SUSPENDED FURNACE / CRAWL SPACE

SUSPENDED FURNACE / CRAWL SPACE
INSTALLATION

INSTALLATION

The furnace can be hung from floor joists or installed on suitable blocks
or  pad.  Blocks  or  pad  installations  shall  provide  adequate  height  to
ensure the unit will not be subject to water damage. Units may also be
suspended from rafters or floor joists using rods, pipe angle supports or
straps. Angle supports should be placed at the supply air end and near
the  blower deck. Do not support at return air  end of unit. All  four sus-
pension points must be level to ensure quite furnace operation. When
suspending the furnace use a secure platform constructed of plywood
or other  building  material secured  to  the floor joists. Refer to Figure  4
for typical crawl space installation.

SECTION III: FILTERS

FILTER INSTALLATION

All applications require the use of a field installed accessory filter. All fil-
ters and mounting provision must be field supplied. Refer to Tables 5 &
16 for accessory external filter kit options.

NOTES:

1. Air velocity through throwaway type filters may not exceed 300 feet per minute (91.4 m/min). All velocities over this require the use of high velocity filters.
2. Air flows above 1800 CFM require either return from two sides or one side plus bottom.

SIDE RETURN - EXTERNAL INSTALLATION

Locate and knock out the square corner locators. These indicate the
size of the cutout to be made in the furnace side panel. Refer to Figure 5.

Install  the  side  filter  rack  following  the  instructions  provided  with  that
accessory.  If  a  filter(s)  is  provided  at  another  location  in  the  return  air
system,  the  ductwork  may  be  directly  attached  to  the  furnace  side
panel. An accessory filter rack is available for mounting the filter exter-
nal to the cabinet.

IMPORTANT:

Some accessories such as electronic air cleaners and

pleated media may require a larger side opening. Follow the instruc-
tions supplied with that accessory for side opening requirements. Do
not cut the opening larger than the dimensions shown in Figure 1.

HORIZONTAL APPLICATION

Horizontal Filters

All filters and mounting provision must be field supplied. Filters(s) may
be located in the duct system external to the furnace or in a return filter
grille(s). Filters(s) may be located in the duct system using an external
duct filter box attached to the furnace plenum. Any branch duct (rectan-
gular or round duct) attached to the plenum must attach to the vertical
plenum above the filter height. The use of straps and / or supports is
required to support the weight of the external filter box.

IMPORTANT:

Air velocity through throwaway type filters must not

exceed 300 feet per minute (1.52 m/m). All velocities over this require
the use of high velocity filters. Refer to Table 15.

When a furnace is installed in an attic or other insulated space,
keep all insulating materials at least 12 inches (30.5 cm) away from
furnace and burner combustion air openings.

FIGURE 3:

Typical Suspended Furnace / Crawl Space Installation

In any application where temperatures below freezing are possible,
see “BELOW FREEZING LOCATIONS”.

1” MAX. BETWEEN
ROD & FURNACE

SUPPORT
ROD

6” MIN BETWEEN
ROD & FURNACE

1” MAX. BETWEEN
ROD & FURNACE

ANGLE IRON
BRACKET

TABLE 5:

Filter Sizes

CFM

(m³/min)