Lennox Europe explains the choice of R410A and multi-scroll compressors for its range of roof tops, chillers and packaged air conditioners rather than the screw compressor/R134a alternative.

 

The main argument centers on seasonal efficiency: most installations operate at full load for less than 5% of the year and the multi scroll solution gives the best solution when judged on its European Seasonal Energy Efficiency Ratio (ESEER). This is  illustrated by the Eurovent average ESEER for aircooled chillers in ratings 200?600 kW which is 4.25 for scrolls and 3.75 for screw machines. Also scrolls cost less to maintain than screw machines which need a complete overhaul after 20,000 hours operation. Replacement cost is also lower?typically 6,000?8,000 for a R410A multi-scroll  compared with 20,000?25,000 for a R134a screw machine. Another advantage is said to be the acoustic ‘signature’ which is said to be less aggressive to the ear because it is free from the high frequency noise associated with the screw machine and makes it easier to attenuate.