I have one of these and I love the proportional day and night built into it without adding anything to it. It was well worth the price. I have it attached to a 6 shelf rack with 15 feet of heat tape and it works great. Keeps 92 degrees in the day time and 90 int he evening. I set the day time temp to start at 0830am and the night to start at 0830pm. Also it has an alarm that sounds if it reached 5 degrees hotter or cooler than what you have it set at. And also an alarm if it has a critical error and the system shuts down. There is also a fail safe on it so if you lose power it will remember what temps and times were set so you will not have to set it again. I love it and would recommend it to anyone for a thermostat.