Has anyone mounted a sub in the ceiling? I was thinking of mounting a downfiring svs in an enclousere I would make in my attic to protect from elements and leave the bottom open with a grille simalar to a heating grill. I would like to do this to keep peace in the house as my wife is not thrilled with the size of the svs.
Any thoughts?

That's definitely not a good idea. Not all the sound a sub makes comes from the woofer. All SVS subwoofers are ported, and a lot of the bass sound comes from the port(s). You would seriously mess with the sound of your SVS by mounting it in your attic.

If the size of the SVS is really that large a WAF issue, I'd consider getting a smaller sub before building an attic enclosure for it.

I bet JohnK or 2x6 can help with this better than I.

However, I've read many times of people building and mouting sub enclosures in the floor or walls of their houses. These typically are DIY projects; Peter rightly points out that the engineering of a Hsu or SVS intends the product to "live" in the same room as the listener.

But how about working on a design that lives in the crawlspace rather than the attic space? I think you'd be much happier, unless you rearrange your seating so that you are sitting on the ceiling instead. If you have a DIY system that is "ported" into the room (via a floor vent - like a heat register almost) and structurally coupled to the floor joists, you do have some advantages. Namely, that the size of the enclosure ceases to be a design issue. Of course, it won't be "cheaper" and may not be "better" than an off-the-shelf design. But there are options.

if you can still return the svs i would and try to get something smaller.
The HSU 1220 is 12 inches(but really tall) and can be turned on it side. this way you can put it under a couch or something.\

i wouldnt go for the attic option. Part of the expierence of the subwoofer is being able to feel it. and if the subwoofer isnt on(or in) the ground you are losing out.