The chiller itself should have a calibration function. Look around, I'm sure you can find instructions on how to do it unless someone has one and can chime in.
Never tried this heater, using eheim heater and they are the best so far with a controller. I'll try to figure out which one is actually give you the right temperature. If you have a mercury filled thermometer or get one, they are suppose to be more accurate and see which one is off. i'm also in the 180g club .