Hot Water temp dropping off? ecotec plus 831

[Jellyman]

hi Guys hoping you can help, we had a ecoTec plus 831 fitted about 2 years ago, all is great with this and we have saved hugely on our bills!!! but the last few months we have noticed that the hot water drops off on temp the longer we use it?
so if I start to run a bath it is red hot for a few mins then merely hot ie can hold my hand under it.
also the shower no longer gets any hotter past medium warm. (I have changed the shower mixer as I thought this might have been the issue a few months ago)
the water is set to 65C and the pressure is showing as fine.
the heating is working fine.
any ideas?
many thanks

 

[Agile]

WE would need to know the exact temperatures and also the flow rates to start to be able to guess what may be wrong.

There can be many causes of boiler malfunctions! An engineer's task is to come to a conclusion in every case!

Tony