Carrier 48HE003---006 Installation, SLAB MOUNT Horizontal Units Only, Fire, Explosion Hazard

!	WARNING
FIRE, EXPLOSION HAZARD
Failure to follow this warning could death and/or
property damage.
Disconnect gas piping from unit when leak testing at
pressure greater than 1/2 psig. Pressures greater than 1/2
psig will cause gas valve damage resulting in hazardous
condition. If gas valve is subjected to pressure greater than
1/2 psig, it must be replaced before use. When pressure
testing field-supplied gas piping at pressures of 1/2 psig or
less, a unit connected to such piping must be isolated by
manually closing the gas valve(s).

	INSTALLATION
48HE,HJ
	Unit is shipped in the vertical discharge configuration. To convert
	to horizontal discharge application, remove duct opening covers.
	Using the same screws, install covers on duct openings in
	basepan of unit with insulation-side down. Seals around
	openings must be tight. (See Fig. 1.)

C06108

Fig. 1 ---Horizontal Conversion Panels

Step 1 —Provide Unit Support

ROOF CURB

Assemble and install accessory roof curb in accordance with instructions shipped with curb. (See Fig. 2.) Install insulation, cant strips, roofing felt, and counter flashing as shown. Ductwork must be attached to curb, not to the unit. If electric control power or gas service is to be routed through the basepan, attach the accessory thru-the-bottom service connections to the basepan in accordance with the accessory installation instructions. Connections must be installed before unit is set on roof curb.

IMPORTANT: The gasketing of the unit to the roof curb is critical for a watertight seal. Install gasket supplied with the roof curb as shown in Fig. 2. Improperly applied gasket can result in air leaks and poor unit performance.

Curb should be level. Unit leveling tolerances are shown in Fig.

3.This is necessary for unit drain to function properly. Refer to Accessory Roof Curb Installation Instructions for additional information as required.

SLAB MOUNT (Horizontal Units Only)

Provide a level concrete slab that extends a minimum of 6 in. beyond unit cabinet. Install a gravel apron in front of

condenser-coil air inlet to prevent grass and foliage from obstructing airflow.

NOTE: Horizontal units may be installed on a roof curb if required.

ALTERNATE UNIT SUPPORT

When the curb or adapter cannot be used, support unit with sleeper rails using unit curb or adapter support area. If sleeper rails cannot be used, support the long sides of the unit with a minimum of 3 equally spaced 4-in. x 4-in. pads on each side.

Step 2 —Field Fabricate Ductwork

Secure all ducts to roof curb and building structure on vertical discharge units. Do not connect ductwork to unit. For horizontal applications, field-supplied isolation flanges should be attached to horizontal discharge openings and all ductwork should be secured to the flanges. Insulate and weatherproof all external ductwork, joints, and roof openings with counter flashing and mastic in accordance with applicable codes.

Ducts passing through an unconditioned space must be insulated and covered with a vapor barrier.

If a plenum return is used on a vertical unit, the return should be ducted through the roof deck to comply with applicable fire codes.

A minimum clearance is not required around ductwork. Cabinet return-air static pressure (a negative condition) shall not exceed 0.35 in. wg with economizer or 0.45 in. wg without economizer.

These units are designed for a minimum continuous return-air temperature in heating of 50_F (dry bulb), or an intermittent operation down to 45_F (dry bulb), such as when used with a night setback thermostat.

To operate at lower return-air temperatures, a field-supplied outdoor air temperature control must be used to initiate both stages of heat when the temperature is below 45_F. Indoor comfort may be compromised when these lower air temperatures are used with insufficient heating temperature rise.

Step 3 —Install External Trap for

Condensate Drain

The unit’s 3/4-in. condensate drain connections are located on the bottom and side of the unit. Unit discharge connections do not determine the use of drain connections; either drain connection can be used with vertical or horizontal applications.

When using the standard side drain connection, ensure the plug (Red) in the alternate bottom connection is tight before installing the unit.

To use the bottom drain connection for a roof curb installation, relocate the factory-installed plug (Red) from the bottom connection to the side connection. The center drain plug looks like a star connection, however it can be removed with a 1/2-in. socket drive extension. (See Fig. 4.) The piping for the condensate drain and external trap can be completed after the unit is in place.

All units must have an external trap for condensate drainage. Install a trap 4-in. deep and protect against freeze-up. If drain line is installed downstream from the external trap, pitch the line away from the unit at 1 in. per 10 ft of run. Do not use a pipe size smaller than the unit connection (3/4 in.). (See Fig. 5.)

Step 4 —Rig and Place Unit

Inspect unit for transportation damage, and file any claim with transportation agency. Keep unit upright and do not drop. Spreader bars are not required if top crating is left on unit, and rollers may be used to move unit across a roof. Level by using unit frame as a reference. See Table 1 and 2 and Fig. 6 for additional information. Operating weight is shown in Table 1 and 2 and Fig. 6.

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