Noisy combi boiler - please help!!!

[vapourtrail04]

Hi,

I have a Worcester Heatslave Highflow 3.5 combination boiler. It is about 12 or 13 years old and seems to work ok (hot water could be a bit hotter).

My problem is when the boiler is heating hot water (ie when running a tap) it makes a continuous groaning and sometimes screaming noise. The problem only occurs when drawing off hot water. The central heating function makes no noise when heating.

I called out my local central heating Engineer who thought it was a faulty thermostat in the hot water heater. He replaced the thermostat but it still makes a noise. He initally thought it was the heat exchanger, but when I told him the problem did not occur with the central heating he dismissed that idea.

What can the problem be?

Please help - it's driving me mad!

Thanks

 

[Agile]

I dont see how anyone could expect a thermostat to cause that. It sounds as if he just wanted to do something quick to charge you. As he did not fix it I would question if you should have paid him!

It sounds more likely to be scaling or sludge causing kettling but its difficult to guess without hearing it. That might explain the poor hot water performance.

The boiler output on central heating will be lower so the operating conditions will be completely different.

Tony Glazier

 

[vapourtrail04]

Is de-sludging or de-scaling an operation I could do myself? If so how do I go about it?