You probably have defective timer.
I test timers, and some timers arrive defective.
I have not tested WH21, so check with your friend about the indicator light.
Mechanical dial timers make audible noise, and dial should rotate as time passes and keep exact time. If dial is not rotating correctly on new timer, then something is not working correctly. The level of timer is not an issue. It sounds like the motor gear is not engaging with dial.
To test timer noise, click manual override lever. You will hear same noise each time timer turns on-off.
WH21 is SPST 21amp timer which turns off one hot wire to water heater.
WH21 is rated to work on 4500Watt 18.75 amp water heater. Or smaller wattage.
Check label on side of water heater for wattage. WH21 is not rated for 5500Watt water heater.
There are many water heater timers:
Electronic timers give more precise time control and option for shorter on-off periods.
Electronic timers are quieter and don't need to be reset after power outage.
http://waterheatertimer.org/Boxtype.htmlMore expensive Intermatic WH40 timer is rated for greater capacity, and has replacement motors and trippers. WH40 is noisy too, but will last for years. WH40 is SPDT so it turns off both hot wires to water heater. I prefer SPDT, and have tested WH40 and other timers shown on link above.
To order extra parts for WH40:
http://www.grainger.com/Grainger/timer-accessories/timers/electrical/ecatalog/N-8hiAdd a comment for more free help.
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