Why are filters of any kind required when a proper cleanse and inhibitor job has been completed on a system? Is it simply to act as an indicator of a failed job?
Cleaning is always less than 100% perfect in practice! The older the system, the more sludge that is likely to be present to remove during cleaning, but the paradox is that on the older systems you also have to clean more gently due to risk of leaks. This means that less aggressive cleaners have to be used, and even with Powerflushing perhaps only 80% of the debris is removed. You could remove 100% of the debris by acid cleaning, but with risk of leaks and consequent damage to the property, plus cost of replacement leaking radiators perhaps. The amount of acid (say Fernox DS-40) is also directly related to the amount of sludge. It might take 5 packs or more of DS-40 to 100% clean an old system at a considerable cost in chemicals and extra labour = five flushes. So, there is also a consideration of cost-effectiveness here. Powerflushing is a labour intensive process as we know. Therefore, the up-shot is that you have to look upon cleaning and Powerflushing as a risk management process n
