I'm not the only person to mention that there is no information provided to tell you which terminal is +ve or -ve. I contacted the supplier (Virtual Village Ltd.), who offered me a refund, as they were unable to provide the information. Sent it back, and promptly got my refund. The reason for all this hassle is that the product does not actually have any markings on it, apart from an arrow indicating the flow direction of the water. Real shame, it looked like a fairly well built unit, but I didn't want to take the chance, connect it wrong and damage the solenoid coil.