Need to update

Hi guys this is my first post on this board just wanted to introduce my self I am a retired HVAC mechanic since 2002 turned inspector and would like to keep abreast of some of the new technology since my retirement trying to keep my mind and body active no rocking chairs for me. My 40 years of HVAC work was both residential and commercial my preference was commercial refrigeration low and medium temp and any type of chilled water systems