Do I need to de-sludge my central heating system or not and inhibitor?
 

I have a Cenebtral heating system with with a combination boiler in my
3 bedroom flat. The system is about 15 years and is sealed.


The system has had inhibitor in the system. I put it in myself. (twice
since I have had to drain the system in the past).

I have just replaced a diverter valve and would like to know what I
should use to add the the system.

I have had some kettling from the boiler for a while now.

I was planning the add Sentinel's X200 de-scaler and X100 inhibitor.
Have I made the right decision? What do others think?
What other additives makes would be better?
Do I need to add a desludger? Would the past inhibitor prevented
sludge to build up?

Chris...