What I Know of: Through-the-Wall Air Conditioners

Now that I've had to buy a wall unit A/C for my studio and I've been living with it for a several days, I learned a couple of things that may be useful to others:

• Through-the-wall is almost twice as expensive as a window unit.  (Most models have a sister unit that is identical except for the mounting, so you can do an apples-to-apples comparison.)  I don't know why this is.  I can't think of a good reason for it.  I would have gone the window unit route to save money except that I didn't want a window in my room for sound isolation purposes.
• You may be thinking:  Well, I'll just buy a window unit and mount it in the wall.  That's a bad idea.  A window A/C needs the window so that the unit can be easily removed for servicing - just open the window.  Mounting it in the wall means you have to tear open the wall if the A/C ever needs repair!  A proper through-the-wall A/C uses a sleeve that is permanently mounted in the wall.   The A/C unit slides in and out of the sleeve for servicing.  Also, a window unit vents through the sides and the back, while a wall unit vents everything through the back.  Mounting a window unit in the wall can interfere with the side venting, which can lead to over-heating or frozen evaporator coils.
• Unfortunately the sleeve is usually sold separately and is yet more money!  There is a logical reason for that though:  They sell it separately so that if you replace the A/C down the road you can continue to use the original sleeve so that you don't have to tear open the wall.
• Through-the-wall and window unit A/Cs are #$@ing loud!  Even the so-called "quiet" models are loud.  It makes perfect sense if you think about it:  A normal centralized A/C for a home typically puts the condenser outside and the blower (fan) in the attic, so you're well removed from the noise.  But a wall or window A/C puts everything in the unit, right up against your room.  It can't help but be loud.
• Don't go overboard with getting an over-sized A/C.  If you get too big a one, it will cool down your room too quickly and not properly dehumidify it.  You'll end up with a cold, clammy room.  I went a little over-sized to account for the fact that I will be running a lot of heat-generating audio gear in mine.