There are many important components to a modern central heating system but, one that should not be overlooked is the corrosion inhibitor.
Inhibitor is essential to the life span of your heating system, protecting it from excessive corrosion, which produces magnetite (black sludge), which not only puts a strain on the pump but reduces efficiency by clogging up radiators.
New systems and boilers should always be flushed out. A proprietary cleaner should be used for this, If possible before the new appliance is fitted.
It can be tempting to seal small leaks by using a proprietary
leak sealing additive, but always check the boiler manufacturers
instructions first as many high efficiency boilers can get clogged heat exchangers if you do.