Home Improvement

How Often Should You Change Central Heating Inhibitor?

We all want our central heating systems to work properly. After all, no one likes being cold during the harsh winter months, right? Using inhibitor is important to ensure our radiators’ ability to warm up our homes. But what exactly does inhibitor do in central heating? Does it need to be changed? If so, how often? Don’t worry, this post has the answers to all of your questions.

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So, if you are someone who:

  • Is wondering when they need to top up the inhibitor in their heating system;
  • Wants to know how to check the inhibitor levels;
  • Is looking for information about what central heating inhibitor is,

Then read on! This post is for you.

What does inhibitor do in central heating?

You may be wondering what central heating inhibitor is and why you need it in the first place. Well, you need it to ensure the safe and proper functioning of your heating system.

A central heating inhibitor is a liquid chemical that prevents the build-up of sludge and limescale in your pipes and radiators. It’s used to break down dirt, rust and minerals and make them easy to extract.

To be able to remove the residue, however, you will need to install a filter. It will catch all the particles and store them until your next boiler servicing. That’s when you can have the filter emptied.

Using an inhibitor improves the efficiency of your central heating system, ensures that your radiators heat up properly and prevents any blockages and damages from occurring.

Keep in mind that using an inhibitor will not get rid of already built-up sludge. To do that, you will need to flush your radiators. You can add the inhibitor afterwards to prevent it from happening in the future.

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How often should central heating inhibitor be changed?

So, how long does radiator inhibitor last? Well, that will depend on multiple factors. Your best bet is to regularly test the levels in your system and add more if needed. You can purchase test kits that are simple and straightforward to use, and they’re quite cheap, too.

Make sure to test the inhibitor levels at least once a year and top up the chemical as needed. Always use the same kind of inhibitor, unless you have drained your entire system and are starting from scratch. In this case, you can opt for a different kind.

If you need to refill your system regularly, for example – due to a leaking pipe, you will need to add inhibitor to it more often. The more water you add, the more diluted it gets and its effects are minimised. So, always test the levels of inhibitor in your central heating system and top up when you need to.

How much inhibitor should I use?

How much inhibitor to use will depend entirely on the size of your heating system. An average bottle of inhibitor will cover about 10 radiators.

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Having troubles with central heating sludge build-up?

You might be in need of a powerflush. Fantastic Services is here to help! We offer a professional and reliable central heating powerflushing service that can bring your radiators back to life. From flushing your system to adding inhibitor, we can handle it for you.

Booking is simple! Just use our online form and choose a time that suits your schedule. The specialists will come equipped with all the tools they need to complete the job and will leave your property spotless afterwards.

Rid your radiators of sludge! Find out more about our professional power flushing service here.


  • A central heating inhibitor is used to prevent the build-up of sludge and limescale inside the pipes and radiators.
  • The inhibitor doesn’t remove build-up sludge, to do that you need a radiator flush.
  • Using an inhibitor improves your heating system’s efficiency.
  • You should aim to test the inhibitor levels at least once a year and top them up as necessary.
  • A bottle of inhibitor will cover around 10 radiators.


Did you find this post useful? Do you have any additional questions about central heating inhibitors? Share them with us in the comments below!

Image source: shutterstock / koya979

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