I am on my 3rd in 8 years Mira ALT shower. Intermittent problems as follow:
Turn power on to shower, push start button, water drips out and after a few seconds all the lights flash.....or this will happen 2-3mins after shower has run correctly for a few mins.
I have tried to re-prime, and have run through the re-set programme but water stops running before this is complete and all the lights will flash.
Another day it will work perfectly!!
There is no difference if I am using other water appliances.
The 3 same showers that have been fitted have all suffered the same problems, plumbed in by qualified plumbers.
Very annoying, so any suggestions please.

Blanks, January 2016

It may be because of cold water - the shower stalls until the desired temperature is reached. Good to begin with because the temperature of the water entering will be that of the house - then as the flow continues much colder water enters the shower and needs more power to warm it up.

Your plumber(s) may neglect to explain this - they get much more money if they install a new shower for you.

Does this problem happen only in the winter?

Your statement - There is no difference if I am using other water appliances - is confusing.

I know nothing of showers - I just guess. I think the shower(s) are limiting the flow rate due to the difference between the temperature of water coming in and the temperature required for the heated water going out.

Stay clean..., January 2016

"after a few seconds all the lights flash"

All meaning what, exactly?

There are, according to the manual I found at http://www.mirashowers.co.uk/onlinecatalog/pdf/1073791_w2_b.pdf FOUR lights but pages 23, 24 and 25 of that document suggests there is NO fault indicated by all FOUR lights flashing.

Please clarify or RTFM a bit closer.

XXX, January 2016