Mira 7.5kW - intermittent hot/cold and low flow rate

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.

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 all the above are OK then you probably need a new pilot valve

The pilot valve is a common fault

Turn off water and power

Put something in the waste just encase you drop a screw!

Remove cover

Remove splash plate at pipe entry

Remove 4 screws from 'U' clamps and 'U' clamps

Later models have “Torx” screws so you will need a “Torx” screwdriver with a T10 Bit.

Remove screw above letter 'A' on drawing

http://www.showerdoc.com/shower-spares/mira/electric-showers/mira-parent-16-mira-sport---post-1992

Ease pilot valve forward (if there is no movement on the pipe work you will have to disconnect it at the inlet connection take care to hold the brass body with pliers when slackening the nut)

Swap the wires over from one pilot valve to the other one by one

Then reassemble

Turn on water and allow the water to come thru unit before switching on power.

Easy init!!!!!

Link to Pilot valve

http://www.showerdoc.com/shower-spares/mira/MIRA-419-87-Pilot-Valve