I hook up my Python water changer to my garage sink and I mix hot and cold water until it "feels" like a right temp match to the tank - you should definately use a water conditioner to get rid of chrorine and/or chloramine in your water.
I use a Python as well and simply place a stick thermometer, an aquarium style which hangs on the tank, and mix the hot and cold from the tap until it reaches a temperature a few degrees cooler than what I want it.
When I say a few degrees cooler, I mean 3 degrees cooler. I have read that most fish like a slight temperature change and that some fish are stimulated to spawn.
In my 55g tanks, with a 50% water change, 75 degree incoming water mixing with 78 degree tank water only produces about 1 1/2 degree cooler tank.