Installation - Operation - Maintenance manual (IOM) • AIR COOLED CHILLERS & SPLIT UNITS - 1106-E • 25 •
10) Check suction and discharge pressures and compressor suction and discharge temperatures.
11) Check chilled liquid entering and leaving temperatures.
12) Check outdoor air temperature.
13) Check liquid refrigerant temperature at the condenser outlet.
These verifications should be made as quickly as possible with a stable cooling load, i.e. the cooling load of the
installation should be the same as the capacity developed by the unit. Measurements taken without heeding this
condition will result in unusable and probably wrong values.
These verifications can only be made once the proper operation of all safety devices and unit controls has been
established.
5.2 - OIL CHARGE
Units have a complete operating charge of oil when they are shipped, and there is no need to add any oil before start
up or afterwards. Note that unit shutdowns by the differential oil pressure switch are usually caused by other
problems than a lack of oil in the refrigeration circuits. Overcharging with oil can cause serious problems on an
installation, particularly for the compressors. The only time any oil might need adding is when a compressor is
replaced.
5.3 - REFRIGERANT CHARGE
Self-contained units have a complete refrigerant charge at the time they are shipped. This charge may need to be
topped up when the unit is installed or at other times during the service life of the unit. Additional charge can be
introduced through the Schrader valves to appropriates positions. Every time fluid is added, check the state of the
charge with the sightglass provided to that effect on the liquid line and also by the amount of liquid subcooling at the
condenser outlet.
IMPORTANT
- Start up and commissioning must be conducted by LENNOX authorised engineer.
- Never shut of power to the crankcase heaters except for lengthy service operations or seasonal shutdown.
Remember to power up the crankcase heaters at least 24 hours before the unit is restarted.
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