Pump continually running

When the hot water has been used there appears to be a pump continually running. it continues all afternoon and in the evening. Is this correct or is it a fault?

What determines the pump to run are the sensors
Page 6 in the book Figure 1:2
Items listed as number 7 DHW sensor and number 8 incoming cold water sensor.
Which in turn tell tells the pump via PCB to heat the water to the preset temperature.
Fingers crossed it is not the board!
Mike
MGC/H2O
Norfolk