Mines a drop in Aqua Logic that's in the garage (similar to below link). Although it may work a little harder during summer I've never had a problem with it. Of course it's oversized for the tank and really keeps the temp a nice 79-80. Matter of fact when the stupid controller locked up with both the chiller and heaters powered on my tank went to a nice 56 degrees.

BTW, I'd highly recommend this one also if you were thinking about a drop in. One less pump to heat up the water, and eat up electricity.

http://www.marinedepot.com/md_viewIt...product=AL1219