NAPC-09 portable AC unit double hose mod

Made this mod for cheap NEOLINE NAPC-09 portable AC unit to fully isolate its condencing coil and cool it with outside air only. This keeps constant pressure and prevents hot air from leaking inside the room and significantly increases cooling efficiency. 

AC units that take air from inside the room and have only one hose to vent hot air outside create low pressure zone inside the room. And because no room is airtight, this leads to constant inflow of new air through gaps in doors and window frames.

This particular mod made for the model that I have, but it was made in China in de'longhi factory and I suspect that this unit may be sold under other brand and model names.

Models are made 6mm thick with an intention of making walls act like thermal insulation. Print it with thin walls and sparse infill to make it as hollow as possible.

Some soft foam tape 3-4 mm thick has to be added to the inlet box to seal the gaps between the printed model and AC unit rear side.

Inlet box has to be printed in 5 parts and glued together. I used CA glue. Inlet funnel and inlet box have matching 1.8 mm holes so small pieces of filament can be used as locating pins while gluing parts together.

The upper part of the inlet is secured to the outlet by two M4 screws with two M4 heat set inserts. The bottom part is secured by two screws that hold original back panel.