I changed mine out to the Hunter from Walmart. I just hooked up the high speed wire as was stated above. The OE t-stat used 6 wires but I only needed 4 for the Hunter. That's because it has batteries for power and I left the low speed fan wire off. It's much more accurate ans doesn't have the 5 degree swing. It is literally a 15 minute installation. Just keep an extra set of batteries in a drawer because when they die you lose your heat and AC. It does have a low battery icon so there would be plenty of warning.