My water changer was fully automatic. I ran it with an aquacontroller with water solenoids for both drain and fill.
If you want to figure out the tank temp swing, fill up the 180 after you get it planted (and before you add fish). Do a 10% or 20% water change (of course try and do the math for what water level to drain too) and refill with cold water. Voila.
I am still not a big fan of the hot water, but do as you may. Too many things that could be a potential problem. Cold water is a lot easier to correct than scolding water. I try and take all precautions before hand and think of the worst (ie, what if the knob for the hot and cold water are accidentally adjusted, or the ball valve for the cold is closed, or there is a significant pressure drop in one not the other, etc. etc.)
If you have a temp controller, obviously, you could have programming that would terminate the water change if temps got to a certain point (I had my water changer set up to do a water change if the temp hit 80 degrees for any reason, say heater broke or stuck on, or metal halides ran hot that day, whatever).
You don't need to be drilled to run a sump, but this was just something I threw out there. Some people get paranoid about water levels dropping, etc.
Water changers are no joke. They are an incredible resource, but don't get too comfortable with the convenience. You still need to check it periodically and make sure things are working status quo.
I still larger water changes manually from time to time.