I've spoken to the guy who fitted the heat exchanger last year and he said exactly the same as you. He recommended changing the radiators or having a power flush??? Do you think it's worth it?
Hi
When I turn on the hot water the boiler bangs, screeches and then the boiler turns off. Also the water is running hot, warm then cold, this has only happened in the last few days since I've been using the heating and hot water. Its running on central heating but its not giving out hot...