Nas19320,
I do not run a chiller but my house stays pretty cool. If you count my 20 gallon frag tank which runs off the same fuge as my 55 gallon I actually have 3- 250w MH (2 standard MH & 1 - HQI MH) I also run 220w of VHO actenics. Usually the only time heat has been an issue is when my wife's parents watch the kids and they turn off the AC in the summer and my tank gets up to 85 degrees! (ugh - in-laws!!!)
Mark