If you have a pump start relay, the AC-powered OpenSprinkler is probably the best option because while we have tested the DC-powered version with several common pump start relays, I also know it doesn’t work with all. So if the pump start relay is rated 24VAC, the best bet is AC-powered OpenSprinkler. Of course you can always try out the DC-powered one and if it doesn’t work for the pump start relay, send it back and exchange for an AC-powered version.