@gary: one thing you should try to tweak the RF antenna to see if that can extend the range. While the manual suggested a relatively long (17cm) antenna, I’ve sometimes had more success with shorter antenna, and sometimes with the antenna curled inside the enclosure. As you know, the RF transmitter doesn’t come with a pre-installed antenna, so you need to solder a wire antenna. If possible, you can drill a small hole on the enclosure to extend the antenna out of the enclosure, which generally gives you better range. Also, if there are several barriers (like walls, enclosures) between OpenSprinkler and the receiving power socket, those can significantly reduce the range. These are things to consider when checking the transmission range.