The use of Inhibitors and protective chemicals in your heating system is a must . They offer protection again the system rusting and build up of contamination and line scale . There are many brands available on the market but it pays to research a good brand in order to offer maximum protection .
There are a few methods in relation to placing them in your system but the easiest is bay way of a pressurised can being sprayed into the systems filling loop . If there is no filling loop isolating a radiator and draining it then pouring in the liquid via a radiator bleed valve . If the system is a open vented system the inhibitor may be added to the feed and expansion tank usually found in the loft , if there are two tanks the correct one would be the smaller of the two but always seek advice of your unsure .