INTRODUCTION

PETRA Residential Air-Cooled Liquid Chillers (RWCc) with hermetic scroll or reciprocating compressors and R407c  refrigerants, offer a wide range of sizes to meet customer requirements for different applications in residential and commercial buildings.

PETRA RWCc chillers are designed to meet customer requirements by offering state of the art low sound, reliability, high energy efficiency and small physical footprints.

The wide range of cooling capacities and flexible installation arrangement makes RWCc chillers easy to install and maintain.

Each PETRA RWCc chiller is designed to be shipped as a complete factory package which is 100% test run in the factory. Unit capacities in this series range from 2 to 46 nominal tons at 50Hz and from 2 to 54 nominal tons at 60Hz. A wide choice of chiller capacities and options are available to meet most design requirements.

PETRA RWCc chillers consist of highly efficient low-pressure drop coolers and high quality condenser coils with maximized airflow. Condenser coils are equipped with low noise fans with patented design fan and motor mounting.

PETRA RWCc chillers are equipped with an intelligent microprocessor controller to manage the unit’s performance for optimum efficiency at both full load and part load values.

OUTSTANDING FEATURES

Superior Efficiency

The RWCc series exceeds the new ASHRAE 90.1 efficiency levels at both full load and part load efficiency.

Low Noise Chillers

The RWCc  series offers a low sound power level, measured in accordance with the BS IS0 3744 standard, by adopting a low noise scroll/ reciprocating compressors, condenser fans and specially designed refrigerant piping.

Compact Physical Footprint

The RWCc chillers feature compact footprints and the possibility for close-spacing installation to serve the areas that have space constrains.

Outstanding Finishing

• All copper pipes and headers are epoxy painted after being cleaned, to maintain pipe material and brazing protected against all
  external conditions.

• All coil U-Bends are protected with a painted galvanized steel cover plate, mounted at the U-Bend coil side. The plate covers the whole
  U-Bend coil side.

• Suction lines and other insulated pipes are wrapped in cheese-cloth and epoxy painted with the same color as compressor. This
  gives further protection for insulation against weather and other factors.

OUTSTANDING FEATURES

Quality Assurance

To ensure the best performance, all the chillers in the RWC series are:

• Factory test run

• Produced in an ISO 9001-2000 listed manufacturing facility.

• Rated in accordance with ARI standard 550/590.

• Construction complies with the ASHRAE 15 safety requirements.

Easy Installation

Installation is made quick and easy with complete factory wiring, easy listing provisions, factory installed options and start up. To eliminate potential start-up problems, a complete factory test run is performed on each unit.

Design Flexibility

The RWCc chillers meet the same high engineering and performance standards that are characteristics of all PETRA air-conditioning systems. A wide range of capacities and options for the RWCc series are available to meet precise design requirements.

FEATURES AND BENEFITS

Piston Compressor

(For Unit Models RWCc 25 - 55) The piston compressor used is hermetic refrigerant gas cooled with thermal overload protection in each phase. The terminal box is rain-tight with direct online starting. It features high performance, efficiency and low sound to match the reliability and efficiency of all other PETRA products.

Scroll Compressor

(For Unit Models RWCc 76 and Above) The scroll compressor has two scrolls that are located in the upper part of the compressor above the motor, forming a completely enclosed compression chamber. This provides increased efficiency and excellent reduction in both noise and vibration due to fewer moving parts, less rotating mass and less internal friction compared to other types.

Air Cooled Condenser

PETRA'S air-cooled condenser coils are designed to deliver their duties with optimum performance for all design conditions. Coils are manufactured from seamless copper tubes mechanically expanded into aluminum fins. All coils are air pressure tested at 450 Psi, under water to avoid leakage. They also undergo dry chemical cleaning after manufacturing for optimum system cleanness.

Type-L, heavy wall seamless copper tubes are provided for coil headers. The condenser coils are hydrostatic pressure tested in accordance with the UL 1995 standard.

Direct Driven, Condenser Propeller Fans

All condenser fans are of the axial type, sickle - shaped blades, statically and dynamically balanced, selected for optimum efficiency and maximum sound power reduction. The fan blades are driven by an external rotor motor and protected by a wire guard made from steel, coated with oven-baked, electrostatic polyester powder coating.

Condenser Fan Motors

           - All fan motors are of high efficiency external rotor motor with permanently lubricated bearing.
           - Six pole induction type motor.
           - Motors feature class F insulation provided with inherent motor protection.

Brazed Plate Heat Exchanger Cooler (BPHE)

(For Unit Models: RWCc 25 - 160) The brazed plate heat exchanger cooler is a complete heat exchanger which consists of stainless steel plates, permanently brazed together using pure copper filter material. The plates are stacked together and form flow chambers for two fluids.

BPHE cooler is used for one stage application with a maximum allowable working pressure of 435 Psi.

The cooler is insulated with 3/4” closed cell foam insulation.

Shell and Tube Cooler

(For Unit Models: RWCc 210 - 630) High efficiency DX shell and tube type cooler with inner grooved tubes to optimize the cooler’s efficiency. The cooler is tested and stamped for refrigerant side working pressure of 360 Psi and waterside working pressure of 150 Psi, which comply with applicable sections of the ASME standard and in accordance with the European codes ISPESL and TUV. The cooler’s water baffles are fabricated from brass for maximum corrosion resistance and the cooler is provided with water vent and drain connection plugs. The cooler is insulated using 3/4” closed cell foam insulation as the standard insulation thickness. Other thicknesses are available as options.

STANDARD FEATURES

Construction

• Galvanized, formed sheet metal chiller base

• Air-cooled condenser allows less installation space requirements

• Easily accessible system components

• Galvanized mesh guard around chiller perimeter

• Weatherproof with ample space for easy access to power and control panels

• Modular design with multiple compressor execution provides flexibility for varying load conditions and avoids total shut down of the chiller
  during service of any of the refrigeration circuits.

• Heavy structure unit with weatherproof,polyester powder, electrostatic paint, oven-baked to ensure maximum gloss and hardness.

• Heavy duty mounting chassis for the whole unit with weatherproof, polyester powder, electrostatic paint, oven-baked to ensure maximum
  gloss and hardness.

•Anti-vibration mounts under compressor(Rubber-in- Shear Type).

Refrigeration

• Independent refrigeration circuit for each compressor

• Fully charged unit with R407c refrigerants

• Liquid, discharge and suction pipes are all hard copper pipes which are formed using the CNC highly accurate pipe bending machine to
  minimize pipes brazed joints and increase system reliability.

• All exposed copper piping of the refrigeration circuit are epoxy painted after being cleaned.

• Expansion tank (one in system) - Loose item.

• Components of each refrigeration circuit include:

                 - Thermostatic expansion valve
                 - Liquid line solenoid valve
                 - High/Low safety pressure switches (capsule type, factory pre-set)
                 - Charging points with charge nipples
                 - Liquid line shut off valve
                 - Disposable filter drier

Electrical

• Weatherproof Electrical Panel: All power and control components including the microprocessor controller will be assembled inside
  the electrical panel coated with weatherproof, oven-baked polyester powder, electrostatic paint, with IP55 index protection.

• Microprocessor controller for full management of the chiller’s operation and safety circuits

• Smart lead-lag operation for compressors

• Short cycling protection for compressors (time delay)

• Freeze protection through water-out probe

• Low ambient based on ambient control down to 7.2°C by cycling fan (ON-OFF) for units with 2 fans or more. For units with one fan, a speed
  controller can be used as an optional feature.

• Control voltage is 220-240V for all components

• Control transformer for microprocessor controller

• On/Off switch for each compressor

• Starting contactors for compressors and condenser fan motors

• Direct Online start

• Inherent motor protection for each compressor

• Inherent motor protection for each condenser fan motor

• General alarm

• Voltage monitor controller

• Control circuit breaker

• Pump interlock as protection for whole unit

• Control circuit breaker for short circuit protection

• Key-Lock and door handle for the electrical panel

• Control terminal strip for easy connection with electrical board and easy field installation

• Free terminal for remote ON/OFF connection

• Free terminal for general alarm output

• Power supply monitor (phase failure relay)(For unit models RWCc 76 and above)

• Single point power connection for electrical panel (refer to electrical data tables)