noisy boiler

[flippy]

I have an old back boiler regulary seviced. After the heating and water has been on fpr a few hours the boiler becomes very noisy. Can best be described as a high frequency whinning or very loud vibration.
Any ideas. Heating and Water all appears to work fine apart from this.

 

[Strachan]

May well be the pipework that needs some attention. All very well having the boiler serviced, but have you had the system itself cleansed and inhibitor added?

 

[flippy]

Good point. Have only done the boiler in the 7 years I have been in the house. incidently, only makes the noise when the central heatings on. Water only seems ok.

As I have to drain the system to replace 2 rads can anyone recommend whether I should take the opportunity to clean the system out or should I just add inhibiter when I refill.