ACOUSTICAL CONSIDERATIONS — Proper acoustical considerations are a critical part of every system’s design and operation. Each system design and installation should be reviewed for its own unique requirements. For job specific requirements, contact an acoustical consultant for guidance and recommendations.
In general, to reduce noise, consider the following:
•Locate mechanical room and ducts away from noise sensitive locations. Whenever possible, work with the architect to locate the equipment rooms around the perimeters of restrooms, hallways, fire escapes, stair wells, etc., to reduce noise transmission. This allows not only for isolation from radiated sound but also enables the contractor to route duct systems around sensitive locations.
•Construct the equipment room of concrete block or use a double offset stud wall with interwoven insulation. Seal all penetrations.
•Design the system for low total static pressure.
•Use suitable vibration isolation pads or isolation springs according to the design engineer's specifications.
•A flexible canvas duct connector is recommended on both the supply and return air sides of units to be connected to system ductwork.
•Use a minimum of 15 ft of return ductwork between the last air terminal or diffuser and the unit.
•Insulate supply and return ducts with
•Round duct is recommended. If rectangular ductwork is used, keep aspect ratios as small as possible (i.e., as close to square as possible).
•Avoid any direct line of sight from return air grilles into the unit's return. If return air is to be ducted to an equipment room, an elbow should be installed within the equipment room.
•Running a return air drop to near the floor of the room will aid in sound attenuation.
•Do not exceed the recommended supply duct velocity of 2,000 fpm.
•Do not exceed the recommended return duct velocity of 1,000 fpm.
•Use turning vanes on
•Place isolation springs under each corner and under each compressor if utilized.
ASSEMBLING MODULAR UNITS — 50BVT,U,V,W,X 30 to 60 ton units ship in the number of pieces shown in Table
2.Reassemble the unit. Use the loose hardware provided in the main
1.The filter/economizer section ships bolted to the main air- conditioning section and can be removed in the field. When reattaching the filter/economizer section to the main
2.If the unit has 2 filter/economizer and 2 main air- conditioning sections (40 through 60 ton units), bolt the remaining filter/economizer section and main air- conditioning section together, as in Step 1.
3.For units with 2 filter/economizer and 2 main air- conditioning sections, use the provided unions to assem- ble the water connections between the 2 additional sections joined in Step 2.
4.For units with multiple air conditioning sections, connect the condensate drain hoses from the “B” side of the unit to the drain manifold on the “A” side of the unit.
5.For unit sizes
6.For VAV units only, connect the plenum tubing, coiled behind the VAV control panel, to the bulkhead fittings located in the discharge of the supply fan. This connects the high pressure supply to the high side of the duct high static pressure switch.
CAUTION
Remove all shipping blocks, if any, under blower housing or damage to the fan may occur.
Step 3 — Install Ductwork — The VAV units must use a “pair of pants” configuration as shown in Fig. 15. Refer to the Carrier System Design Manual or ASHRAE (American Society of Heating, Refrigerating and Air Conditioning Engi- neers) standards for the recommended duct connection to unit with 2 fans.
A
B
NOTE: A = 11/2 to 21/2B | |
|
Fig. 15 — Typical Fan Discharge Connections for
Multiple Fan Units
A supply air outlet collar and return air duct flange are pro- vided on all units to facilitate duct connections. Refer to dimen- sional drawings (Fig.
A flexible canvas duct connector is recommended on both supply and return air sides of the units to be connected to the system ductwork.
All metal ductwork should be adequately insulated to avoid heat loss or gain and to prevent condensation from forming on the duct walls. Uninsulated ductwork is not recommended, as the unit's performance will be adversely affected.
Do not connect discharge ducts directly to the blower outlet(s). The factory filter should be left in place on a free return system.
If the unit will be installed in a new installation, the duct system should be designed in accordance with the System De- sign Manual, Part 2 and with ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers) proce- dures for duct sizing. If the unit will be connected to an existing duct system, check that the existing duct system has the capaci- ty to handle the required airflow for the unit application at an
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