There were two fans, both Panasonic FV08VQ3, a very common, excellent, extremely quiet 80 cfm unit that in fact is very easy to install. Light from bathrooms could be seen from the attic, corresponding of course to heat loss.
|Begin with knowing the guts of each fan must be removed. All screws are Phillips drive. Collect four that release the lightweight cover plate. Three more are machine screws that release the motor assembly, not dropping out.|
In each case, the fan body flange was traced, and drywall was cut through to reveal half of the width of a truss bottom chord.
Drywall scraps, and the dead fans, were tossed into the trash heap of loose-fill insulation above.
|The solution available to me, with the flexible grout I offer, was to reset scraps in properly-framed openings. This was possible in part because drywall was strong, 5/8" fire-rated, for condominium construction. The repair is as-new on three edges with wood backing. I will adequately glue the unsupported side, with flexible grout.|
|Here are the two openings, ready for fan insertion. 2x3 frame sides spaced 10 1/2" are attached to truss chords, with 3" deck screws. The openings in the other direction are 10 5/8".|
Fan adapter assemblies, still wired, stand securely, with bottom flanges engaging the underside of the drywall.
|Each fan body is pushed through from below, and is loaded against 2x3 rails, with 2 1/2" deck screws.|
Complete reassembly of fans can happen now, ready for paint.
The adapter assembly top clips are rotated onto fan bodies, completing tight assembly, from above.
|Foil-tape the ducts, and reset cable staples.|
The above is an exercise in blogging, further learning what is possible with the free resources of google.com. I think this sharing of experience is a necessary investment to fight installation error, and waste of energy. I have started another blog as another way of trying this. I think an installation methods forum of some kind is needed, and will hope to at least be a contributor.