Carrier 50HCQ07 Installation Instructions Manual

11Fig. 6 — Unit Leveling TolerancesStep 5 — Field Fabricate DuctworkCabinet return-air static pressure (a negative condition) shallnot exceed 0.35 in. wg (87 Pa) with economizer or 0.45 in. wg(112 Pa) without economizer.For vertical ducted applications, secure all ducts to roof curband building structure. Do not connect ductwork to unit.Fabricate supply ductwork so that the cross sectional dimen-sions are equal to or greater than the unit supply duct openingdimensions for the first 18 in. (458 mm) of duct length fromthe unit basepan.Insulate and weatherproof all external ductwork, joints, androof openings with counter flashing and mastic in accordancewith applicable codes.Ducts passing through unconditioned spaces must be insulatedand covered with a vapor barrier.If a plenum return is used on a vertical unit, the return shouldbe ducted through the roof deck to comply with applicable firecodes.UNITS WITH ACCESSORY ELECTRIC HEATERSAll installations require a minimum clearance to combustiblesurfaces of 1 in. (25 mm) from duct for first 12 in. (305 mm)away from unit.Outlet grilles must not lie directly below unit discharge.NOTE: A 90-degree elbow must be provided in the ductwork tocomply with UL (Underwriters Laboratories) code for use withelectric heat.Step 6 — Rig and Place UnitKeep unit upright and do not drop. Spreader bars are required.Rollers may be used to move unit across a roof. Rigging mate-rials under unit (cardboard or wood) must be removed PRIORto placing the unit on the roof curb. Level by using unit frameas a reference. See Table 2 on page 9 and Fig. 7 for additionalinformation.Lifting holes are provided in base rails as shown in Fig. 7. Re-fer to rigging instructions on unit.Before setting the unit onto the curb, recheck gasketing oncurb.Position unit on roof curb so that the following clearances aremaintained: 1 /4 in. (6.4 mm) clearance between the roof curband the base rail inside the front and rear, 0.0 in. clearance be-tween the roof curb and the base rail inside on the duct end ofthe unit. This will result in the distance between the roof curband the base rail inside on the condenser end of the unit beingapproximately 1 / 4 in. (6.4 mm).Although unit is weatherproof, guard against water from higherlevel runoff and overhangs.After unit is in position, remove the compressor access panel.Holding the blocking between compressors with one hand, cutthe strapping. Carefully remove the blocking without damag-ing tubing, wiring, or controls. Remove the strapping and re-place the access panel.After unit is in position, remove rigging skids and shippingmaterials.CAUTIONFailure to follow this caution may result in damage to roof-ing materials.Membrane roofs can be cut by sharp sheet metal edges. Becareful when placing any sheet metal parts on such roof.ABCMAXIMUM ALLOWABLEDIFFERENCE IN. (MM)A-B B-C A-C0.5 (13) 1.0 (25) 1.0 (25)WARNINGFailure to follow this warning could cause personal injury.For vertical supply and return units, tools or parts coulddrop into ductwork and cause an injury. Install a 90-degreeturn in the return ductwork between the unit and the condi-tioned space. If a 90-degree elbow cannot be installed, thena grille of sufficient strength and density should be installedto prevent objects from falling into the conditioned space.Due to electric heater, supply duct will require 90-degreeelbow.CAUTIONFailure to follow this caution may result in equipmentdamage.All panels must be in place when rigging. Unit is notdesigned for handling by fork truck when panels or pack-aging are removed.If using top crate as spreader bar, once unit is set, carefullylower wooden crate off building roof top to ground. Ensurethat no people or obstructions are below prior to loweringthe crate.CAUTIONFailure to follow this caution may result in equipmentdamage.All panels must be in place when rigging. Unit is notdesigned for handling by fork truck when panels or pack-aging are removed.