Why Use Inhibitors?

Using an inhibitor is a crucial component in maintaining a clean, healthy and efficient central heating system. It could mean the difference between a system that is both cost-effective and works efficiently, and one that leads to a broken boiler.

What is a central heating inhibitor and what does it do?

An inhibitor is a chemical solution that prevents corrosion and limescale formation in central heating systems and provides protection against microbiological contamination and installation debris.

Corrosion occurs when water comes into contact with the metal components found in a heating system. If left untreated, tiny pieces of rust will start to break off and settle at the bottom of pipes and radiators. Over time, as a result of mixing with other dirt and limescale in the system, a brown sludge will build up. This sludge will cause blockages, stopping water from freely circulating around the system - affecting its performance and causing it to work harder. This results in increased running costs for householders, a larger environmental footprint, and in worst-case scenarios, a complete system breakdown.

Using an inhibitor significantly reduces this rate of corrosion, and is therefore, a critical way of ensuring that a central heating system continues to perform as it should, as well as supporting a boiler manufacturer’s warranty.

When should an inhibitor be added to a central heating system?

Changes to Building Regulations Approved Document Part L, which came into force on the 15^th of June 2022, included a number of updates that relate to the commissioning and maintenance of central heating systems. 

Every heating system installation, service and repair must now be undertaken in accordance with BS 7593:2019, which means a system must be chemically cleaned if it is heavily contaminated, a new radiator / extra pipework is added, or a new boiler is installed – and an inhibitor added.

To ensure the long-term protection of central heating systems, an inhibitor’s concentration levels should also be checked (and if necessary reapplied) annually, as part of a boiler or system service. Systems should be topped up with an inhibitor every five years – as a matter of course - or the quality of system water tested using a postal laboratory service or on-site test to ensure full protection against corrosion and scale

How should I dose a system?

You can dose a system directly via a radiator, the water tank of an open vented system or the filling loop or in-line system filter of a sealed system.  This should be done in line with the inhibitor manufacturer’s instructions, or ideally by a qualified heating engineer.