1) Check that plumbing is correct:
http://waterheatertimer.org/Water-heater-recirculation-system.html

2) The timer has 2 choices: thermostat operation or timed operation.
http://waterheatertimer.org/images/IMG_9325-grundfos-timer-800.jpg
http://waterheatertimer.org/How-to-set-timers.html

3) Add comment and say what you discover

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