I always assumed AC units were generally noisy.

I am not suggesting the following, nor do I have these models,
I simply am pointing them out as they are specifically designed
to be quiet. That is a relative term. Mine is not quiet in dB,
but the sound it does generate is white noise and seems more
quiet than the "old window units that make a lot of racket.." which
I am familuar with.

http://www.lennox.com/products/overview.asp?model=HSX15

http://www.alpinehomeair.com/view.cf...4-EEDF580C3D74

http://www.trane.com/Residential/Pro...ers/XL19i.aspx