This is the super heat recovery ventilator in the back units, seen on yesterday's tour.  The 3" tubes will bring indoor air the the HRV, which will draw heat out of the incoming air and pump the air out through a single vent to the outside.  Then the HRV will pull air inside, transferrting the heat to the incoming air.  Neato!

This is the super heat recovery ventilator in the back units, seen on the  owner’s tour yesterday. The 3″ tubes will bring indoor air the the HRV, which will draw heat out of the incoming air and pump the air out through a single vent to the outside. Then the HRV will pull air inside, transferring the heat to the incoming air.