Air Conditioner Installation Advice Needed

Last night it took me three hours to install a new window air conditioner (it turned out I got one that is way too huge for my bedroom). I live on the second floor and I am worried that the unit will fall out of the window either killing someone below or ripping out my window. Anyone else have similar worries due to air conditioners?

Some facts:

  • I have a regular casement window.
  • The unit weighs 100 - 120 lbs.
  • Due to the structure of my window, we couldn’t screw the bottom of the air conditioner to the sill. So, we jammed a towel and wood underneath it to make the unit level
  • The wing things are screwed to the window.
  • The window has a metal bracket blocking it from opening wider than the unit.
  • We screwed in these sill clamps that are outside the building and hug the unit to the window.

Am I worrying unnecessarily? Does this sound good?

First of all, having a unit too large for the space is not a good idea. It will cycle off and on too often and it will cool the room, but not dehumidify it.
When I installed units in a similar situation I bought an adjustable bracket that attaches to the sill and has an arm that braces against the outside of the building (i bought it at Home Depot).
By the way, the unit should not be level but should be tipped slightly towards the outside (to allow water to drain). This will also increase the strain on your window if that is all that is holding the ac. I would not trust the window to hold the ac, especially a unit as large as yours. One thing you might do is to move more of the unit inside so that less weight is hanging out your window, but I strongly recommend using the afore mentioned bracket.