General

equipment. Follow all safety codes. Wear safety glasses and work gloves.

WARNING

Before performing service or maintenance operations on unit, turn off main power switch to unit and open all dis- connects. More than one disconnect switch may be required to deenergize this equipment. Electric shock haz- ard can cause injury or death.

CAUTION

Use care in handling, rigging, and setting bulky equipment.

Omnizone™ 50BV indoor packaged units are very flexible for a variety of applications. These self-contained units are available as water-cooled or remote air-cooled air conditioning units. The 50BV units are available with either constant vol- ume (CV) or variable air volume (VAV) controls. In addition, the 50BV unit is available as a water-cooled heat pump. Final- ly, Omnizone 50BV units are available in two cabinet styles. Nominal 18 through 30-ton units are constructed in a single- piece, unpainted galvanized cabinet. Nominal 30 through 60-ton units are available as modular units, and can be taken apart for easier installation. Modular units are built using an un- painted, galvanized steel cabinet with steel framework, and can be easily disassembled without breaking the refrigerant lines. See Table 1 for a model number reference by application.

Each unit contains multiple scroll compressors piped in separate refrigerant circuits. Each water-cooled circuit includes a coaxial (tube-in-tube) condenser, TXV (thermostatic expan- sion valve), individual evaporator coils, and all interconnecting piping. Water-cooled units are shipped fully charged with refrigerant. Remote air-cooled units are shipped with a nitrogen holding charge.

Each unit is equipped with one or two forward-curved cen- trifugal blowers, to ensure quiet air delivery to the conditioned space. Constant volume units operate at a single, adjustable fan speed and provide zone temperature control using a standard commercial thermostat. For VAV applications, the unit is sup- plied with a variable frequency drive(s) (VFD) that automati- cally adjusts blower speed to maintain a constant, adjustable duct static pressure. Compressors are automatically staged to provide supply air temperature control (VAV applications) or zone temperature control using a two-stage commercial ther- mostat (CV applications).

The 50BV units have removable access panels for easy servicing. These panels allow access to controls, compressors, condensers, VFD(s) (if applicable), evaporator motors, blow- ers, belts, pulleys, and refrigeration components.

MAJOR SYSTEM COMPONENTS

Constant Volume (CV) Units

MAIN CONTROL BOARD (MCB) — The main control board for the 50BVC, E, Q, T, U, and V units provides both controls and diagnostics including:

•Condensate Overflow Protection prevents unit operation in the event that the drain pan clogs (optional sensors required).

•Random Start provides a programmable start with a range of 30 to 60 seconds.

•Anti-short Cycle Timer provides a 5-minute delay to pre- vent compressor short cycling.

•Low Pressure Bypass Timer bypasses the low-pressure switch for 90 seconds to avoid nuisance trips during cold start-up.

•High Pressure Switch Delay is a one-second delay that pre- vents nuisance trips at start-up.

•Brownout/Surge/Power Interruption Protection is a 20-second moving scale that works in conjunction with the random start timer to delay unit start when a nuisance lock- out would otherwise have occurred. This allows the water pumps to restart and establish water flow.

•Alarm Output contacts provide remote fault indication.

•Test/Service Pin is a jumper that reduces all time delay settings to 6 seconds during troubleshooting or operation verification.

•Reset occurs after a 5-minute delay when a fault condition occurs. When the timer expires, the unit will restart. If the same condition occurs a second time, the unit will be locked out.

•Lockout Reset requires that the unit power be cycled at the unit controller via either the thermostat or unit disconnect.

NOTE: The refrigerant circuits on dual compressor models are completely independent. If either stage has a fault condi- tion the remaining stage will continue to operate without interruption. A freeze (optional sensor required) or condensate overflow lockout will shut down both refrigerant circuits.

• LEDs are provided for diagnostic purposes.

Variable Air Volume (VAV) Units — The 50BVJ, K, W, and X units come equipped with a Carrier 6400 Comfort Controller and a VFD. Refer to the 50BV,XJ Controls, Opera- tion and Troubleshooting manual for details.

NOTE: The VAV units utilize face split coils and should not be operated below 50% of nominal airflow to prevent coil freezing.

Table 1 — Model Number Reference By Application Type

MODEL	TYPE*	AVAILABLE CAPACITY	CONSTRUCTION	CONTROLS
50BVC	Water-Cooled	18 to 30 nominal tons	Single-piece	CV
50BVE	Remote Air-Cooled	18 to 30 nominal tons	Single-piece	CV
50BVQ	Water-Cooled Heat Pump	18 to 30 nominal tons	Single-piece	CV
50BVJ	Water-Cooled	18 to 30 nominal tons	Single-piece	VAV
50BVK	Remote Air-Cooled	18 to 30 nominal tons	Single-piece	VAV
50BVT	Water-Cooled	30 to 60 nominal tons	Modular	CV
50BVU	Remote Air-Cooled	30 to 60 nominal tons	Modular	CV
50BVV	Water-Cooled Heat Pump	30 to 60 nominal tons	Modular	CV
50BVW	Water-Cooled	30 to 60 nominal tons	Modular	VAV
50BVX	Remote Air-Cooled	30 to 60 nominal tons	Modular	VAV

LEGEND

CV — Constant Volume VAV — Variable Air Volume

*All units are cooling only unless specified.