A careful installer starts with a room-by-room heat loss calculation, not a rule of thumb, then proposes a ducted system, ductless indoor units, or a mix. Expect questions about insulation, windows, and the condition of any existing ductwork.
Permits run through the Building Department, which handles building and electrical permits on Abington's OpenGov portal, and a heat pump's new circuit falls to the town's Wiring Inspector. If an oil tank comes out as part of the switch, the Fire Department's tank removal permit applies as well.
On install days, the outdoor unit is set on a pad, stand, or bracket, line sets run through the wall, and indoor equipment is mounted or tied into the ducts. The installer should start the system, walk you through the controls, and explain what winter defrost cycles look like so they don't alarm you.