Hello, I have a 240v water heater with a machincal timer which went bye-bye after I installed it over 15 years ageo. Those darn plastic gears finnaly broke. So I bought a Intermatic EH40. The line is 240v with 3 wires (white, black, and ground) which matches the water heater wires. But because the EH40 is a DPST and my old switch was a SPST, i'm having a brain freeze about how to connect it. I'd rather not return the unit. How do I connect my water heater to the new timer/switch?