I have had a few of these over the years. Last year when I set it up, water was leaking at the manifold so I went to Canadian Tire and bought a new one. I set it up, tested it with the manual valves, and promptly left for Alaska for a good part of the summer leaving a house sitter in charge. It turns out that zones 3 and 4 would not activate with the system and when I got back a good part of my lawn was in pretty rough shape. I figured I had just gotten a dud, so I ordered a new one this spring from Amazon. After using it for a couple of weeks, I realized that it had the exact same problem - zones 3 and 4 would not activate. I tried a battery change and a so on, but it really is a defect. Based on this experience, I would have to say that I suspect that there is an inherent problem with these water timers and will not buy one again. I returned it to Amazon for a refund, since I caught this one while I could still return it, and ordered a Rainbird. The Rainbird looks very similar but on inspection is not just the same unit with a different name on it, so I am cautiously optimistic that it will work. My suggestion is to give this Melnor product a miss, or if you do buy it, watch it closely to make sure that it really works while you are still in the return window.