In article , "Carolyn"
says...
Since I had a Combi fitted in the loft, I have noticed that
a) my electric shower now runs fine,with no need to turn it on for approx 5 minutes,
to give it time to stop blasting freezing then hot water, alternately and
b) my washing machine now does its final rinse in very hot water.. If I am around when a
cycle finishes,
the clothes are steaming hot.. On a 40deg wash, I could end up with shrinkage, etc...

Any idea why this happens, and is it possibly due to mis-plumbing?? All the household taps
are fine
and run correctly, as does the CH,so I can`t fathom it out..

Logic would suggest that the hot and cold feeds are reversed on the
washing machine - disconnect it and run each tap in turn into a bucket
(or the hoses into the sink if they'll reach) to see which one runs hot.
Don't know about electric showers.