Leaking coolant is a major problem. The standard for most small heat pumps is r412a and it is problematic. To make the installs cheap, these systems use flare

Leaking coolant is a major problem. The standard for most small heat pumps is r412a and it is problematic. To make the installs cheap, these systems use flare fittings that almost all seem to leak. Couple that with the fact the 412a systems run at high pressure and you get a lot of leaking refrigerant. No HVAC techs I’ve met like the 412a systems and most seem to be hoping for more sanity from r32, though that will have its own set of problems (flammability)