Potterton Performa 28 Hot Water Problems

[Access Gas]

Hi I have a Potterton Performa 28 And when the hot water is turned on the tempurature reading on the boiler reaches 80* C within minutes and shut the boiler down untill the temp reading goes below 80* but the issue is that the water doesnt even reach luke warm.

Is it worth cleaning the DHW heat exchanger? or replacing dhw thermisitor? or any other ideas?

 

[jefaz]

It sounds to me it's the dhw heat ex. It doesn't sound like a thermistor fault