Why do refrigeration manufacturers recommend only 80% to 90% of the original system charge when retrofitting to some HFCs?
The new refrigerants are considered “higher efficient” and they are trying to sell refrigerants under the requirement of fewer component change outs. For example, an expansion valve works to full capacity if it has full liquid (subcooled liquid) to its inlet. If the expansion valve is considered oversized for the new refrigerant then the valve capacity will decrease if the refrigerant starts to boil off before the inlet of the valve. The vapor molecules take up more space than the liquid molecules, therefore, less refrigerant passes through the valve with vapor. Copeland recommends valves to be sized accordingly and to charge the system as basic rules apply: expansion valves are charged by clearing the sight glass in the liquid line at high load (subcooling) and the cap tubes are charged by evaporator superheat at low load conditions. If only a percentage of charge is used the compressor could overheat during an extended high load condition.
Related Questions
- Compressor manufacturers are very specific about what is added to a refrigeration system. How do they feel about Spectroline?
- Why do refrigeration manufacturers recommend only 80% to 90% of the original system charge when retrofitting to some HFCs?
- Is it prohibited to charge an air conditioning or refrigeration system with HCFCs or HFCs? ..........
