In the US at least, the heatpump is present beginning with the 2013 model year, in all but the S model. Maybe I'll just live with the heater as it - is is frigid here, with no end in sight! If you can give us the insulation or tubing sizes, and maybe a picture or even a drawing, I'll add this to the Tips & Tricks. If not I can still add a general description.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
BAFX OBDII Dongle
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.