Potterton Performa 28 heating and hot water only at 50%?

Hello all,

First of all I have read many of these posts and can only commend everyone on here for helping people out, hopefully someone can help me now...

The issue I have is that I'm not getting any errors at all on the boiler however the hot water dosn't get as hot as it should do/used to do and also the heating seems to be operating at 50% as it should do/used to do

any ideas?