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What is a chemical flush?

If you’ve noticed cold patches in your radiators, then it may be time for a chemical flush.
If you don't know what one is, then we’re here to help.

Why do I need a chemical flush?

If your radiator is cold even though the heating is on, then we recommend a chemical flush - over time debris can build up in your central heating system which impacts the energy efficiency of the system. 

A chemical flush is a standard process that is usually conducted when a new boiler has been installed. It removes rust and debris inside your system that helps clean your boiler, pipes and radiators which causes heated water to flow through more easily and efficiently.

Benefits of a chemical flush

A chemical flush will clean out the build-up of debris in your central heating system. This helps to boost the efficiency of your heating, protects from rust & scale build-up and increases the lifespan of your boiler - helping to save money in the long term.

The reduction of corrosion and blockages means that there is less likely to be any damage to individual parts, so you should have warmer radiators and a quieter system – basically, it’s like having a brand-new energy-efficient system.

How often should I have a chemical flush?

Your boiler will only need a chemical flush a few times in its life.

A good indicator for when your system needs a chemical flush is if the bottom of your radiators are cold even though the heating is on. There are other factors such as amount & type of debris in the system, how old your system is and how well it's been maintained over the years - but a cold radiator bottom is a strong indicator.

We should mention new central heating systems will have a lot of debris in the system after installation, so a chemical flush should always be administered.

How long will a chemical flush take?

A chemical flush should only take a few hours - it's all dependent on your central heating system type and the number of radiators you want to flush.

When the chemical flush has been completed, your engineer should be able to show how much your system has improved by measuring radiator temperature and comparing it to what it was previously.

You'll see and feel the benefits immediately.

How much does a chemical flush cost?

There’s a variety of factors that can impact the cost of a chemical flush, such as size & age of your central heating system. 

Although the initial cost of a chemical flush can be high, it will absolutely help to reduce your heating bills thanks to the improved energy efficiency.

The total flush cost can vary from many engineers, ranging from around the £300-£700 mark. When your engineer flushes the system, the need for additional repairs may present themselves which may increase costs.

The price of a chemical flush is completely free of charge if you purchase a boiler from us - it comes as standard with all our installations.


There you have it, a basic overview of a chemical flush and the benefits associated. If this sounds like a service you’d be interested in feel free to call us on 0800 61 22 302 and we’ll happily help your system become more energy efficient - saving you a lot of money in heating bills.