Do not permit overhanging structures or shrubs to obstruct outdoor air discharge outlet, com- bustion air inlet or vent outlets.
DUCTWORK
Ductwork should be designed and sized according to the methods in Manual Q of the Air Conditioning Con- tractors of America (ACCA).
A closed return duct system shall be used. This shall not preclude use of economizers or outdoor fresh air intake. The supply and return air duct connections at the unit should be made with flexible joints to minimize noise.
The supply and return air duct systems should be designed for the CFM and static requirements of the job. They should NOT be sized to match the dimen- sions of the duct connections on the unit.
When fastening ductwork to side duct flanges on unit, insert screws through duct flanges only. DO NOT insert screws through casing. Outdoor ductwork must be insulated and waterproofed.
Refer to Dimensions and Clearances Figure 13 for information concerning side and bottom supply and return air duct openings.
NOTE: It is recommended that, in Canada, the outlet duct be provided with a removable access panel. It is recommended that this opening be accessible when the unit is installed in service, and of a size such that smoke or reflected light may be observed inside the casing to indicate the presence of leaks in the heat exchanger. The cover should be attached in a manner adequate to prevent leakage.
FIXED OUTDOOR AIR INTAKE DAMPER
This damper is shipped inside the return air compart- ment. It is completely assembled and ready for installa- tion. A damper baffle inside of the hood is adjustable to provide variable amounts of outdoor air intake on units that are not provided with an economizer or a motor- ized damper option. Refer to the Fixed Outdoor Damper Figure 3.
Gasketing and mounting screws are provided in a parts bag attached to the hood assembly. Apply gasketing to the three flange surfaces on the hood prior to installing the hood. Extend gasketing 1/4 inch beyond the top and bottom of the two side flanges to insure adequate sealing.
Adjusting the damper to the desired air flow may be done before mounting the hood into position or after installation by removing the front hood panel or the screen on the bottom of the hood. Damper baffle in position 1 will allow approximately 10% outdoor air flow, position 2 approximately 15% and, to allow approximately 25%, remove the damper baffle.
On units with bottom return air application install the damper assembly over the opening in the side return air access panel. Remove and discard the opening cover and the covering over the hood mounting holes (used for shipping) before installing. Secure with the screws provided.
On units with side return air applications, install the damper assembly on the return air ductwork as close to the unit as possible. Cut an opening 16 inches high by 18 inches wide in the ductwork to accommodate the damper. Using the holes in the hood flanges as a tem- plate, drill 9/64 inch dia. (#26 drill) holes into the duct- work and secure with the screws provided.
If outdoor air intake will not be required on units with bottom return air applications, the damper assembly should still be mounted on the side return air access panel, per the instructions above, to insure moisture is not drawn into the unit during operation. The cov- ering over the mounting holes only need be removed. Do not remove the opening cover.
10 | Johnson Controls Unitary Products |
