noisy central heating system

This system was fitted 18 years ago and is serviced every year. The boiler is a Stelrad, with a DAB 65 pump running 5 x 48" singles,2 x 24" singles and 1 48" double radiators. Recently the boiler started ketteling and making a loud banging noise when the boiler is working. I have flushed the system and added descaler repeatedly, 3 times over three weeks. Then the pump was relaced with a Wilo gold RS 60 , this had no effect except the noise was worse so the DAB 65 was refitted. The noise persists and I am at the end of my tether. Any idea as to what the cause could be? Do I need to think about a new heat exchanger or is there a thermostat in the boiler that may be at fault? Please help.

A proper boiler engineer can probably descale that old bolier of yours and after an hour or twos work, you may well find that your boiler has a new lease of life. Probably for as little as £100.



A lot of probablys, but 18 years is pretty good going, especially nowadays with todays standards.

Thanks for the advice, problem was solved eventually. There was two walls of calcium in the heat exchanger with an air gap in between them and it was cleared eventually by using an extra strong descaler. The system is now silent again.