Energy Tech Laboratories DSH installation instructions Ductwork, Louver Sizing Guidelines

FORM 145.32-IOM1 (908)

DUCTWORK

When installing ductwork, adhere to local Codes and sensible practice. Minimize duct runs and avoid abrupt changes in direction where possible. Allow ample access space for servicing of the coils and changing of filters. Perform regular maintenance on ducts to increase unit life, maintain efficient operation, and reduce accumu- lation of explosive dust. Refer to blower performance charts, and engineer duct runs and accessory pres- sure drop so as not to exceed maximum external static values.

LOUVER SIZING GUIDELINES

One of the key issues in obtaining optimum performance from indoor air-conditioners is the proper selection of the condenser intake and discharge louvers. Unlike outdoor air cooled units, which intake and discharge their cooling virtually unrestricted, indoor units must overcome the resistance of grilles or louvers at the outside wall - plus the restriction of any interconnecting ductwork.

Our indoor air cooled air-conditioners are designed to ac- commodate the external static pressure loss associated with properly sized louvers of the “storm proof” type. This type of louver typically has a free area approximately 40-45% of the actual louver size. To determine the free area required for any given unit, adhere to the following guidelines:

-Size condenser air intakes for 500-750 feet/minute nominal velocity

(Maximum recommended 800 feet/minute)

-Size condenser air discharge for 1,200-1,500 feet/ minute nominal velocity

(Maximum recommended 1,700 feet/minute)

The use of louvers with higher velocities than above may be employed, at the discretion of the engineer/installer, provided that the total air pressure drop does not exceed the capability of the condenser fan and motor. The use of low restriction louvers with shallow blade angles can allow higher face velocities without excessive static pressure loss.

Exceeding the static pressure capability of the con- denser fan will result in insufficient condenser air volume. This will cause a loss in system capacity, and may cause compressor shutdown during high ambient periods. (In- stallation of an oversize condenser motor/drive, where applicable, may be considered in such cases.)

(As a general rule, these velocities will require an intake louver sized approximately 1.25 to 1.5 times the dimen- sions of the duct connection on the unit, and a discharge louver sized approximately 1.5 to 2 times the duct con- nection dimensions.)

Use only louver sections that provide different deflection angles for air discharge and air intake, to ensure the unit does not short circuit. Protect the unit from weather conditions (rain, snow) entering through the condenser air intake. All outdoor air ducts should pitch away from the unit, toward the outside wall. Connect all ducts to unit with canvas section duct connectors or choose another suitable noise and vibration absorbing device.

The Manufacturer will not accept any liability resulting from incorrect instal- lation of this equipment. Follow instal- lation instructions carefully.

Johnson Controls 11