Alpha 280

[andf380]

Went to look at a alpha 280 combi boiler about 10 year old
What is happening is when the heating comes on it makes a loud whistling noise for about 15 mins then stops also when he ran the hot tap the noise stopped but now it as started making the noise whilst the hot water is running could it be the heat exchanger sludged up i am hinking of putting some X800 through the system any ideas
Thanks

 

[Billy Bob Bob]

to give you some insight to this boiler,it became the baxi 105,performa etc,only simpler in baxi guise it sounds like ketterling so yes restriction ie sludge or tired pump