Westinghouse WPAXH-060CA4 Service Manual page 97

WESTINGHOUSE PACKAGE A/C MANUAL R-410A : 220V: 60Hz
15.6 Ductwork
1. Attaching horizontal ductwork to unit
1) All conditioned air ductwork should be insulated to minimize heating and cooling duct losses. Use a
minimum of two (2) inches of insulation with a vapor barrier. The outside ductwork must be weatherproofed
between the unit and the building.
2) When attaching ductwork to a horizontal unit, provide a flexible watertight connection to prevent noise
transmission from the unit to the ducts. The flexible connection must be indoors and made out of heavy
canvas.
Note:
Do not draw the canvas taut between the solid ducts.
2. Attaching down flow ductwork to roof curb
Supply and return air flanges are provided on the roof curb for easy duct installation. All ductwork must be
run and attached to the curb before the unit is set into place.
Follow these guidelines for ductwork construction:
1) Connections to the unit should be made with three-inch canvas connectors to minimize noise and vibration
transmission.
2) Elbows with turning vanes or splitters are recommended to minimize air noise and resistance.
3) The first elbow in the ductwork leaving the unit should be no closer than two feet from the unit, to minimize
noise and resistance.
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