Got some cool pics in this attic. [] The two plumes of frost are at the walls of an upstairs bathroom. This bathroom is not being used, no shower curtain so no long showers, no exhaust fan to leak, just a light fixture on the ceiling that is probably leaking some air. An elderly couple only use the downstairs master bathroom. The insulation between these two frost plumes is wet on top, where you see black on the white fiberglass. Moldy dust, I call that black stuff. The heat pump was going strong to keep the main floor at 68 F. Up in the bathroom, a register is pumping heat in, and a vaulted ceiling above the downstairs living room is supplying even more heat. I think they should pull back the insulation and look for leakage at the wall top plates. Click to Enlarge 53.33 KB Click to Enlarge 51.5 KB Click to Enlarge 55.75 KB