My central heating is working fine. But everytime we use the shower or the bath tub the water temperature keeps fluctuating from warm to hot. I have changed the water pump and the diverter valve but the problem still exists. can anyone help me with this?

zuber, December 2009

Plate heatexchanger inside boiler looks like silver plate is full of sludge thus stop heat transfer to water thus this happen

Mr K, December 2009