I have an over-sized A/C unit for my server room, which is both good and bad. It's good because I have plenty of capacity and can keep the room at 64 degrees in 100+ degree weather (if I so desire) with my current heat load. This means I could add more equipment and not worry about being able to cool it. It's bad because it means that the A/C unit might be short-cycling.
Short-cycling means that the compressor might be starting and stopping too often, which reduces the life of the most expensive component. During the winter, I seem to notice the unit cycling on and off a lot, so I was worried. Since I have temperature monitoring and logging of the room, I decided to extract and plot some data to see if I could see definite temperature swings this way, and thus figure out how often it's cycling.
I plotted a 12-hour subset of data from a relatively normal 40-degree day, and found that the swings were very obvious. I counted about twenty cycles in the 12-hour period, indicating about two cycles per hour, which is definitely within the normal range.
