I'm curious about the install cost. n this case a high wall unit, ground level external timber framed/clad wall and happens to be right next to the main circuit board (which is outside on this '60s build) so a really simple job.
Had a sparky around to do a couple of small jobs recently, should have asked him while he was here about heat pump wiring. He did suggest I replace the main circuit board as it is a bit old and crusty with a mix of porcelain fusible wire fuses and new circuit breakers.