With many refrigeration systems having been shut down during recent periods of low demand - It is essential to safely restart these systems to avoid liquid slugging to the compressor. 

If these systems were simply switched off at the unit control - then safe system start up should be a simple case of switching the unit control back on. 

If the power supply was shut down to the refrigeration system - then safe start up requires careful consideration and possibly some intervention by a qualified technician. 

When the circuit breaker or isolation switch is used to shut down a refrigeration system the compressor crankcase heater stops operating. The crankcase heater must operate for at least 12 hours before starting the system or fatal damage can be arise on the compressor. 

It is suggested to contact your clients to alert them of this possible issue so you can offer your professional services to safely start the refrigeration system. 

When restarting a refrigeration systethe following checks can be performed to enhance reliability therefore protecting the safety of their cold chain and reducing the energy consumption of the refrigeration system. 

System Check List 

Before switching on: 

  • Check the compressor crank case heater has been engaged for a minimum of 12 hours before restarting the refrigeration system 
  • Check the supply voltage 
  • Check and tighten all electrical connections 
  • Check electrical wiring and components to ensure no rodent damage 
  • Check fans spin freely prior to switching on 
  • Check and clean the condenser coil 
  • Check and clean the evaporator coil 

Switch unit on: 

  • Check the fans operate correctly 
  • Check the evaporator superheat is correct (when refrigerated space is close to design temperature) 
  • Check for any abnormal vibrations 
  • Check the refrigerant charge 
  • Check the amperages of major components
  • Check the control system and pressure controls are correctly set and working.  

Following these system checks will help to enhance the reliability and energy efficiency of your client’s refrigeration system.  

*This check list is a guide only. Some sites or applications might have other requirements that are not covered in this procedure.