24 volt or 230 volt?
230 volts is what normally comes out of a wall outlet, and this is also the most commonly used voltage for coin-operated timers.
When the coin-operated timer is installed in a damp environment, for example near a shower, it is safer to use a 24-volt (AC) version. In that case, you will need not only a coin-operated timer but also a 24-volt (AC) transformer (24-volt power pack) to convert the standard 230 volts to 24 volts. The coin-operated timer will then only switch 24 volts (AC), so the solenoid valves must also be 24 volts (AC).
When the coin-operated timer is installed in a damp environment, for example near a shower, it is safer to use a 24-volt (AC) version. In that case, you will need not only a coin-operated timer but also a 24-volt (AC) transformer (24-volt power pack) to convert the standard 230 volts to 24 volts. The coin-operated timer will then only switch 24 volts (AC), so the solenoid valves must also be 24 volts (AC).