CAUTION
Disconnect gas piping from units when leak testing at pres- sures greater than 0.5 psig. Pressures greater than 0.5 psig will cause gas valve damage resulting in a hazardous condition. If gas valve is subjected to pressure greater than
0.5psig, it must be replaced. When pressure testing field- supplied gas piping at pressures of 0.5 psig or less, the unit connected to such piping must be isolated by manually closing the gas valve.
INSTALLATION
Jobsite Survey — Complete the following checks before installation.
1.Consult local building codes and the NEC (National Electrical Code) (ANSI/NFPA [National Fire Protection Association] 70) for special installation requirements.
2.Determine unit location (from project plans) or select unit location.
3.Check for possible overhead obstructions which may in- terfere with unit lifting or rigging.
CAUTION
Do not lift unit with forklift truck. Move unit with over- head rigging only.
Unit Placement — Inspect unit for transportation dam- age. File claim with transportation agency.
Provide clearance around and above unit for airflow, safety, and service access. Do not restrict top (area above condenser fans) in any way. Allow at least 6 ft on all sides for rated perfor- mance, code compliance, and service.
Check unit dimensional drawings for unit arrangement and minimum performance and service clearances.
Do not install unit in an indoor location. Do not locate air in- lets near exhaust vents or other sources of contaminated air.
On units equipped with power exhaust option, high velocity air is exhausted out the hood. Unit should be positioned with at least 10 ft clearance between the exhaust hood and any obstruc- tion. Although unit is weatherproof, guard against water from higher level runoff and overhangs.
Level by using unit frame as a reference. Physical data is shown in Tables 1A-6.
Roof Mount — Check building codes for weight distribu- tion requirements. Unit weight is shown in Tables 1A-1E and 2. Unit may be mounted on class A, B, or C roofing material.
ROOF CURB — Assemble and install roof curb as described in instructions shipped with the accessory. Accessory roof curb and information required to field fabricate a roof curb is shown in Fig. 1-5. Install insulation, cant strips, roofing and counter flashing as required. For unit condensate drain to function properly, curb must be level or within tolerances shown in Fig. 1-5.
STEEL BEAMS — If roof curb is not used, support unit with steel beams along its entire length and then support steel as re- quired. As a minimum, unit must be supported across its width at each lifting lug location.
Slab Mount — Provide a level concrete slab that extends beyond unit cabinet at least 6 inches. Make a slab 8 in. thick with 4 in. above grade. Use gravel apron in front of condenser coil air inlet to prevent grass and foliage from obstructing airflow. Ensure that slab is of sufficient height to allow for con- densate trap of 4 in. on sizes 030-070 or 7 in. on sizes 075-105.
Curb Gasketing
SIZE 030-050 UNITS — After ductwork has been connected to the roof curb, attach adhesive-backed gasketing on all end rails, cross rails, and duct rails. Be sure all joints and corners of gasket are square and flush to prevent possible water leaks. Follow all applicable building codes.
SIZE 055-105 UNITS — After ductwork has been connected to the roof curb, apply gasket material (1/2-in. thick x 11/2-in. wide neoprene) where indicated.
Single-Thickness Gasketing (See Fig. 6-8 for Item Num- bers) — Apply gasketing in the following places:
1.Along both side rails (1) — 2 places, full length
2.Along return air end rail (2) — 1 place
3.Around return air internal duct flange (3) — 1 or 2 places
4.Around supply air internal duct flanges (4) — 3 places
Double-Thickness Gasketing (See Fig. 6 and 8 and Detail A-A) — Locate a line 93/4-in. from the supply air end of the accessory curb. Apply a double-thickness of gasket material along with line per detail A-A.
NOTE: Do not apply gasket material along the outside edge of the curb (area “X”). This pan area of the curb extends out beneath the end of the unit’s air handler section; applying gas- ket here develops a potential water trap area on top of the curb.
Condenser Section Roof Curb (See Fig. 7) — Apply single- thickness gasket along both side rails (5).
Field-Fabricated Ductwork
WARNING
For vertical supply and return units, tools or parts could drop into ductwork and cause an injury. Install a 90-degree turn in the supply and return ductwork between the unit and the conditioned space. If a 90-degree elbow cannot be installed, then a grille of sufficient strength and density should be installed to prevent objects from falling into the conditioned space. Failure to follow these instructions could result in personal injury or property damage due to falling objects.
The 48ZG,ZN,ZT,ZW,Z6,Z8 units are designed for vertical supply/return only. Field-fabricated ductwork must be attached to the roof curb, on to the support steel, prior to the final rigging and installation of the unit. Supply and return duct dimensions are shown in Fig. 1-3.
To attach ductwork to roof curb, insert duct approximately 10 to 11 in. up into roof curb. Connect ductwork to 14-gage roof curb material with sheet metal screws driven from inside the duct.
Secure all ducts to the building structure, using flexible duct connectors between roof curbs and ducts as required. Ducts passing through an unconditioned space must be insulated and covered with a vapor barrier. Outlet grilles must not lie directly below unit discharge. The return duct must have a 90-degree elbow before opening into the building space if the unit is equipped with power exhaust.
Design supply duct strong enough to handle expected static pressures.
Rigging — Do not drop unit; keep upright. Use spreader bars over unit to prevent sling or cable damage. Sheets of ply- wood placed along the condenser coils will provide additional protection. All lifting lugs MUST be used when lifting unit. Level by using unit frame as a reference. See Fig. 9-13 for in- formation. Unit and accessory weights are shown in Tables 1A- 1E and 2. Weight distribution and center of gravity can be found in Fig. 14.
