What Does Central Heating Inhibitor Do?

Central heating inhibitor is a treatment chemical that helps protect compatible boiler, radiator and pipework materials from internal corrosion and scale. Its role is to maintain protection in the circulating water, not to repair leaking parts.

What it helps prevent

• Internal corrosion that contributes to sludge formation.
• Scale deposits where the product is designed to control them.
• Loss of protection after untreated water is added to the system.

Inhibitor is different from cleaner

A cleaner helps remove existing contamination when used as part of the specified cleaning process. Inhibitor maintains protection after the system is suitably clean. It cannot reliably unblock a badly sludged radiator or replace a diagnosis of poor circulation.

Check the concentration, not just the calendar

Test inhibitor concentration as part of routine annual heating-system servicing, using a test suitable for the chemical in your system. Re-dose if the test or the chemical manufacturer’s instructions show that protection is insufficient, and after draining, flushing or water loss where required. Adding another bottle automatically every year can give the wrong concentration.

Follow the chemical, boiler and system manufacturers’ instructions. For background on annual testing, see Fernox’s inhibitor testing guidance.

How much inhibitor should you use?

Use the dosage stated for the particular chemical and the system’s water volume. Bottle sizes and concentrations vary; radiator count alone is only an estimate. Do not mix chemicals unless the manufacturers confirm compatibility. A sealed system’s cold filling pressure is set by its boiler instructions, not by a universal value.