Silver older, freezers, drop-ins and hose leaks are questioned

Question: I have several questions: 1. Are you permitted to use silver solder on the liquid line side? 2. What should the superheat be in freezer refrigerators? 3. Is there a direct drop-in for R-12 without changing the oil? 4. On standard refrigerant hoses what is the loss of refrigerant (for critical charge)?

-Sal Garbesi, Reno's Electric and Refrigeration, Philadelphia

Answer: 1. You definitely can use silver solder on a liquid line. In fact, it is recommended. 2. Superheat in a freezer should be determined by the manufacturer's specifications. Generally, it is about 6 ° F. 3. There is no true drop-in refrigerant for R-12 without an oil change. 4. There should be no loss of refrigerant in hoses if they are not damaged and are rated for the refrigerant in the system.

-Sol Holtzin, CMS, past International president