I know a lot of people feel that water heater timers don't save much, if any, electricity, but before I researched it much I had my friend buy a timer that he found on clearance. After getting it and preparing to wire it in I found that it was a 110v timer and my water heater is of course 220v. Can someone tell or show me how to wire it in and if it will even work? I know how to do basic electrical work but I want to make sure I wire it up correctly and safely. Thanks for any help.
Theoretically it will work if you have a neutral present at the timer. WH's require only 240 volt circuit so there is little chance you will have a neutral. You need the neutral for the 120 volt timer motor. 240 volt timers use a 240 volt motor, and 120 volt timers use a 120 volt motor.
If you have a neutral present, you can hook the timer motor for 120 volt and use timer contacts for 240 volts. This will take some reengineering of the timer. Better to just get the right one. But yes, it can be done.