Cleaning a CH system

[caveman2]

After a recent boiler service it was confirmed that I had kettling. It is a 15 year old Ideal Standard boiler, 2 motorised valves, header tank and 9 rads. It was suggested that a powerflush might be too much for this ageing system.My intention is to drain, refill with F3 and run for 2 days, drain again and twice refill and run before draining again and refilling with F1.
Assuming that protocol is acceptable. Can someone please advise if F3 500ml (which they say is sufficient for up to 16 rads) would be too powerful for only 9. I don't want to have any leaks.
Thanks in anticipation of any advice.

 

[Madrab]

It was suggested that a powerflush might be too much for this ageing system

Who told you that rubbish? If the system was 40years old then maybe but 15, certainly shouldn't be.

500ml of F3 should be fine for 9 rads and the boiler. How bad is the system water?

 

[caveman2]

I've not seen the condition of the system water yet, until I drain it for the F3 introduction. The kettling is not that bad, but hasn't been cleaned or protected for years and my only concern was the over concentration of the cleaner and whether 2 days was enough.

 

[gas112]

sentinel x 200 will get rid of your kettling no need to drain clean etc