Stretch wrote:
Bob,

Be careful of using a wood return grille. The net free opening is not
as large as a metal grille of the same size, that restricts air flow.
If the fins are 1/3 inch apart, replace it with one that has fins that
are 1/2 inch apart. the further apart the fins, the less likely it is
that it will whistle. Aluminum grilles with 2/3 inches between fins
are even better and look nicer. Sometimes you can bend the fins with
needle nose pliers to make the air go straiget in so the air does not
change direction after going through the grille. Or flip the grille
around 180 degrees for the same reason. If the air is moving across
the fins of the grille before or after it goes through, the grille is
likely to whistle. Hope this helps.

Stretch


I called the installer and told him he has a problem and that he'll
either have to increase the duct size or else replace the grille with
something that doesn't whistle. He said he has a heavier grille with the
fins farther apart. I asked him why his crew didn't know this while they
were here installing it. He weaseled around with some bs explanation,
but the real reason of course, is that he used the cheapest grille he
had. Lennox won't send me an owner's manual. They said I have to get it
from the installing dealer. I called a second dealer and told them I
just bought a house that has this model number Lennox in it and I want
to buy a set of owner's manuals. They said they'd be happy to send them
to me for nothing and they'd also like to be the one to do the
maintenance on it and they hope I'll be one of their good customers. I
know I have the warranty, but it doesn't cover routine maintenance. At
this time, without an owner's manual, I don't even know what routine
maintenance is but for sure, I'll go with the 2nd company, not the
installer. I'm assuming any Lennox dealer is authorized to do warranty
repairs.

Bob