Mira 88 mixer

My shower runs red hot when first turned on,
it takes at least 5 minutes before it is usable.It has been plumbed in wrong red=cold
blue=hot,would this make any difference?

Yes. It would not work properly.

Only the manufacturer could tell you how it would behave, but cutting to the chase you need to get the supplied swapped over - this is probably going to be more easily done away from the shower. If you have a pump it will be a doddle.

Not sure in the case of the Mira 88, but...
I THINK IF you can get the valve out of the wall without destroying tiles, etc., you can flip it round 180 degrees (which would fix the problem so long as the thermostat still works). You can also get service kits from Kohler Mira. On the other hand... maybe there's only one outlet, on the top of the 88, in which case swapping the supplies is the only option.

Clearly, if the supply pipes are accessible, that's going to be the easiest option anyway.

Hm, you're right. I should have said that any thermostatic shower won't work properly.

This is because the incoming hot flow is adjusted according to the selected outlet temperature, and relative to the actual outlet temperature. If the inlets are reversed, then the cold flow will be decreased instead of the hot.

However, the Mira 88 is a manual mixer. If it's too hot then the cause is one of these:

1. Faulty valve control;
2. Scaled up cold inlet filter;
3. Blockage in the cold supply;
4. Hot pressure defeating the cold (unusual but possible);

Yup - my mistake. There is no thermostat.