Combi boiler hot cold issue

[Rosszx10r]

Hi we have a 5year old worster bosh 28ijunior it's been running through a water softener for 5years also. So when we run a shower/ bath water goes hot/warm/hot/warm and so on. Run the hot alone stays hot. I bypassed water softener still same issue.

Any ideas would be greatly appreciated

 

[muggles]

A better description would be greatly appreciated...can you expand a little please? It's not entirely clear what your problem is

 

[Rosszx10r]

The water goes hot to warm hot to warm and so on, doesn't stay the temperature?

 

[muggles]

Run the hot alone stays hot.

What does this bit mean?

 

[Rosszx10r]

Run the hot water without mixing. IE. for a bath or shower