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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.

Book a chemical flush

Why do I need a chemical boiler 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 boiler flush is a standard process that is usually conducted when a new boiler has been installed. It removes rust & debris inside your system that helps clean your boiler, pipes & radiators - which helps hot water to flow more easily & efficiently.

Book a chemical flush

Take the worry out of repairs with a Boiler Plan Care Plan

With a chemical flush costing anywhere between £300 and £700, it’s worth protecting your boiler against this and any other unforeseen and expensive maintenance and repair work. With our range of affordable care plans, you’ll never have to sit in the cold again.

Whatever plan you choose, each comes with an annual service to ensure your system is fully maintained and ready to keep your home reliably warm.

Choose from:

  • Service PlanBoiler service every year to ensure it’s working correctly
  • Gold PackageIncludes: 3 call outs per year, annual service, carbon monoxide test.
  • Platinum PackageIncludes: Unlimited call outs, all parts and labour, repairs to the entire heating system, £500 towards a replacement boiler.
  • Boiler Plan Plus Package -For those with a Boiler still in warranty. Includes: Unlimited call outs, all parts and labour, repairs to the rest of your entire heating system.
Take out a care plan

Benefits of a chemical flush


A boiler 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 boiler 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 all depends on your central heating system & the number of radiators you want to be flushed. 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 feel the benefits immediately.

How much does a boiler flush cost?

There's a variety of factors that can impact the cost of a chemical flush, such as the 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 itself 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.