Category - Boilers
Guide author photo

Ryan Gill, Engineer

31 Jan : Updated 18 Apr ● 5 min read

Central heating inhibitor: what it is and how to use it

Reliability, efficiency, and quality - all essential characteristics for a long lasting central heating system. By simply adding inhibitor to the central heating, you’ll not only save money on maintenance but will also ensure your system runs like clockwork. 

This guide explains what, how, and why inhibitor is used. For everything you need to know about inhibitors - you’ve come to the right place.

What is central heating inhibitor?

Made from a number of chemicals in liquid form, they protect your boiler system. This provides your system with a longer lifespan - so you don’t have to worry about repairing it anytime soon. 

Over time, your system and pipes can become eroded with rust and other unwanted materials. These build up creating a ‘sludge’ like substance. In some cases, it may get stuck in some of the main components of your system - preventing it from running efficiently, or at all. 

How to add inhibitor to central heating system. 

The way to add inhibitor depends on the kind of system you currently have. Own a combi heating system? The inhibitor goes directly into your radiators.  If you have a conventional boiler and heating system, the inhibitor goes into the heating tank - usually stored in the loft space. 

Here’s how to fill a central heating system with inhibitor:

Adding inhibitor to a loft tank. 

When adding the inhibitor to the feed and expansion tank in your loft, you’ll need to firstly stop the flow of water into the system. In some instances, you’ll have a valve on your tank which will do this. However, if this is not the case, you’ll need to find your mains water valve and turn it off. 

When the tank is empty, you’ll be able to see the condition it’s in. If it looks like it’s covered in limescale or corroded around the sides, you may need to take measures to clean this tank before you move any further. The inhibitor is then poured into the empty tank. 

Note down the number of radiators your household has - this is a good starting point to determine how much inhibitor you’ll need to use. The flow of water can then be turned back on.

Central heating inhibitor for combi boiler.

If you have a combi boiler heating system, there’s a couple of ways you can add the inhibitor to a radiator. With a towel radiator, simply remove the plug on the top and pour it in. With a normal radiator, you’ll have to apply it into the valve where you would bleed a radiator.

For either method, ensure your entire heating system is turned off and your radiators have fully cooled down. Choose the radiator that you’ll be pouring your inhibitor into, securely shutting both radiator valves. When you’ve attached the inhibitor container to the radiator securely, you can then apply the liquid. Afterwards, turn on your heating for approximately 15 minutes and wait for the inhibitor to travel around your central heating system.

How often should central heating inhibitor be changed?

Central heating inhibitor will need to be changed once a year or so. It will break down over time, meaning minerals and rust build up once more. This means regulating your system’s inhibitor intake ensuring it runs steadily and consistently. 

You should always top up the inhibitor every time your system is drained. This drainage will obviously drain out the inhibitor liquid, so it’s important that you monitor it.

Furthermore, It’s important to find a central heating inhibitor of a high quality to keep your system running efficiently. As we mentioned earlier, you need enough inhibitor for the amount of radiators you have. To put things into perspective, an average sized container of the liquid should cover around 10 radiators. 

You can also use a central heating inhibitor test kit to get an accurate analysis of the concentration in the water of your system. These tests are easy to use and involve collecting water from your system into a sample tube. For more information about inhibitor testing, use our live chat feature to speak with an engineer. 

The benefits of central heating inhibitor.

Using inhibitor is very beneficial to your entire heating system in a number of ways, some of which we’ve already covered. As well as adding inhibitor to heating systems already in use, it’s also a good idea to use it in a brand-new system to help extend the life of it from day one. 

  • Firstly, central heating cleaner and inhibitor will do what it says on the tin. It will clean away the debris and corrosion throughout your system, prolonging its life. The liquid is a healthy applicant for a heating system. 
  • In the long run, you’ll save money on new boiler parts that could be expensive. Without an inhibitor, your system could experience the breakdown of components or blockages. It could fail to work completely without it. 
  • The process is more efficient. Radiators will be hotter much quicker due to the lack of debris filling up the system. 

Central heating inhibitor will ensure your system keeps on working...

Simply add inhibitor to your central heating to allow your system to run competently and smoothly. If you feel you need a little more guidance - you can chat to one of our engineers for free using our live chat feature.

By purchasing your boiler from BOXT, we add the inhibitor as standard during the installation, so there’s no need to worry about the process of adding it to your new system.

Ready to upgrade your boiler?

Ready to upgrade your boiler?

Find a brand new, A-rated boiler that's perfect for your home in just 90 seconds

Get a fixed-price quote