Mira Advance Noisy

The things to check first are.

1 That the main valve coming into your house is fully open.

2 Then check that the valve on the line to the shower is fully open.

these valves are not fully open then there may not be enough water
getting to your shower to cool it properly the overheat safety device will turn
the power off until it cools Then it all starts again

Make sure that the shower head is clean and clear, that the hose isn’t kinked (this can happen just behind the hand set where it is difficult to see) also check the inside of the hose although it can look OK on the outside it could have collapsed internally

If these are OK then you could have a problem with your inlet sensor.

There is a little thing like a watermill wheel that that whirrs round inside it that could be the problem.

http://www.showerdoc.com/shower-spares/mira/MIRA-405-50-Mira-Inlet-Sensor-405-50

(The wheel is in the shower)

If you think that this is where the noise is coming from then I would be tempted to fit the complete flow valve assembly, the sensor is part of the valve the complete valve is easier to fit and the complete valve is easier to fit than the sensor on it’s own.

 http://www.showerdoc.com/shower-spares/mira/MIRA-1643-149-Mira-Flow-Valve-Assembly-(components-Identified-C)--1643-149