A good heat pump install requires many things... - Considering a load calculation will only benefit you and the customer by properly sizing the equipment. - Adding supplemental heat where applicable (dual fuel or restive heat) - A TESP within spec (may require duct mods) - A deep pleated filter with no particulate bypass (this will ensure your evap keeps clean and will prevent or erase drain clogs) - A clean refrigeration system (nitrogen brazing) - A pressure test that passes - A proper evacuat