Miami University Increases Efficiency with BITZER

Objective: Site review and start-up assistance for replacement of York Screw with BITZER Screw.

Location: Miami International University of Art and Design

Miami International University of Art and Design – Florida

Existing System and Compressor Information (York Millennium Screw Chiller):

// Chiller consists of two equal size DXS45LASA46-50 screw compressors.

// Compressor part number is 364-49094-215.

// The chiller is rated at 209.1 tons with R22 refrigerant.

// Each circuit is rated at 105 nominal tons per ARI standard 550/590-98.

// Each circuit has an economizer.

// Each circuit utilizes an external oil separator with an initial charge of 5 gallons Type “L” synthetic oil.

// System is set-up with across the line starting.

// Each compressor has 3-5/8″ suction service valve and 2-5/8″ discharge service valve.

// Compressor weight is 1310 lbs. (less service valves).

// Electrical data for each compressor: 460 volt / 163 RLA / 893 LRA with DOL starting.

Work Performed to Replace DXS45 to CSH:

// Removed the existing York DXS45 Screw Compressor and external oil separator.

// Installed (2) 7′ long “U” channel for mounting of the BITZER CSH Screw Compressor. The channel was then attached to the base frame by drilling 3/4″ holes.

// The BITZER CSH was attached to the mounted channel with 5/8″ bolts after holes were drilled to match the footprint.

Piping of the Suction and Discharge Connections:

// Re-piped the existing suction and discharge connections from each end of the DXS to the top of the CSH8553-110-4PU screw compressor. The existing pipe was only removed to allow (1) 90° elbow in the suction piping and (2) 90° elbows to be used on the discharge piping.


// Removed existing economizer piping to the DXS45 screw compressor.

// Capped off the existing piping for circuit #1 economizer and left in place.

Suction and Discharge Pressure Transducers:

// Re-used the existing suction and discharge pressure transducers. The suction transducer was re-installed into the BITZER service valve.

// The discharge transducer was installed into the upper pipe plug underneath the BITZER discharge service valve.

// The upper connection allows for the system pressure to be read by the controller.

Liquid Injection (When Required):

// Installed liquid injection oil cooling for the CSH using the existing piping from the economizer. Re-used the existing solenoid valve and only required @ 6ft of 5/8” copper tubing and 4-5/8” 90° elbows to allow @ 8” of tubing rise from the inlet to the compressor.

// Installed the liquid injection controller inside of the control cabinet and drilled a 3/8” hole through the panel to route the sensor cable to the compressor.

// Mounted the liquid injection sensor 6” from the discharge service valve and insulated the sensor.

// At the existing operating parameters, liquid injection oil cooling is not required. It was decided to installed liquid injection as a “worse case” scenario.

Capacity Control:

// The York DXS45 installed on this chiller utilizes only 1 capacity control solenoid.

// This requires the installation of a standalone controller and/or other suitable device to control the BITZER capacity control solenoids, depending on type of set-up. A simple dual set point capacity controller is suitable.

// Installed the BITZER capacity controller with temperature probe into the control cabinet.

// Installed the temperature probe in the same location as the existing system probe on the fluid outlet piping.