Project Saves Thousands, Lowers Power Consumption, and Reduces Noise
Industrial Cooling Corporation (ICC) of Metuchen, NJ, recently retrofitted a 10-ton reciprocating compressor with a BITZER scroll compressor (ESH736-4SU) to keep overall client costs down, reduce power consumption, and minimize noise. Replacing large, inefficient recips with high-efficiency screw compressors on chillers and rooftop units is standard practice in many areas, but it is unusual to convert smaller recips to scrolls.
Because scroll compressors are taller than recips, Daniel Greenhalgh, the job foreman, had to modify the sheet metal panel above the compressor compartment to gain 5”. Once the recip was removed and the scroll mounted in the cabinet, Greenhalgh mounted an APR valve on the left side of the new compressor. He then installed a solenoid valve on the APR outlet and electrically paralleled it with the liquid-line solenoid to allow the compressor to pump down. A discharge check valve was also installed for pumpdown and to make sure no liquid refrigerant backed up into the compressor dome.
Mike Chiovaro, ICC account executive, explained that the APR valve is a capacity modulation and dehumidification device for direct expansion A/C systems. By regulating refrigerant flow, it allows direct expansion systems designed for full load to maintain acceptable air quality during varying load conditions. He added that the active portion of the coil stays below dew point at all times, thereby keeping the system in the dehumidification mode and ensuring longer run-times.
Isolation refrigerant ball valves were installed on all three lines of the APR to allow for complete isolation. “This enabled us to be sure the system was charged and operating to the original specifications,” said Chiovaro. “After pulling down the system and charging with R22, we then opened the APR isolation valves and checked operation. We created a low load on the unit to make sure the APR reacted correctly.”
After completing the startup procedures, the BITZER scroll was running at full load (no APR operation) with 75° F intake air and 50° F discharge air and only using 13 amps. The scroll used 2 amps less than the second-stage recip compressor beneath the scroll that was running unloaded with the same temperatures and voltage.
When the customer walked into the room to inspect the installation, he commented on how quiet the new scroll compressor was compared with the old recip model. He did not hear it running at all, because the recip compressor below it was also running.
Chiovaro said the installation required more time to retrofit, but the overall cost was thousands less than installing a “drop-in,” and the customer benefited by seeing lower power consumption and lower sound levels in his data center.
Steps in the Retrofit
- Reclaim the R22 refrigerant (to be reused at completion).
- Remove and dispose of failed compressor.
- Modify sheet metal panel, located above stage-one compartment.
- Install mounting plate and set new BITZER scroll compressor (model ESH736-4SU).
- Modify refrigerant piping to meet compressor discharge and suction connections.
- Provide and install one new liquid line filter drier.
- Provide and install one new discharge check valve.
- . Provide and install one new APR valve.
- Provide and install all needed piping, fittings, refrigerant solenoid, and ball valves to install the APR.
- Install a new contractor.
- Terminate and reconnect power.
- Evacuate and charge circuit with reclaimed refrigerant.
- Start up system and record pressures, amperage, voltage, superheat (adjust if needed), and sub-cooling.
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