Alpha 240 E, making scratching noise

[Zehroni]

Alpha 240 E
I drained the system completely today, injected it with system cleaner, and refilled it again. The central heating working ok. DHW start O K however, the as the water start get hotter, the boiler star making scratching noise like and the water start getting cold in same time the radiator close to the boiler get hot. Then the noise gets lower the water gets hotter and so on and so forth. What is could be? Could it be circulation or air still trapped somewhere inside the boiler.

 

[gas112]

Your cleaner may have lifted some dirt from system an got it trapped on the seating of the 3 way valve(diverter)

 

[Zehroni]

Dear Gas112,
Many thanks for your contribution. This might the case. The water came out very dirty with recognised size black particles which I have not seen in the past when I clean or drained other systems. The cleaner I am using is corrosion guard and the instruction says that I have to leave for 28 days. Do you this problem will disappear with time Or do I have to do something about it now before the diverter value gets damage, by the way the diverter value is only three years old.

 

[gas112]

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