How Ofen Central Heating Inhibitor required?

What does inhibitor do in central heating?

Over the time, your hardworking central heating system and pipes naturally erode and get a build-up of rust, limescale and other unwanted materials. This creates a thick, gloopy ‘sludge’-like substance that can sit stubbornly at the foot of your radiators and pipes – stopping the warm water from flowing through each radiator and pipe properly. This stops your radiators from heating up efficiently.

This can start developing cold spots, faults, blockages, burst pipes, your boiler being put under too much pressure, etc. etc. All problems that can often rear their ugly heads in deep mid-winter. Adding central heating inhibitor primarily prevents the build-up of sludge in the heating systems. Its mix of chemicals can also break down dirt, rust and minerals and make them easy to extract.

Central heating inhibitor is a clear or a pale yellow liquid that contains:

  • Potassium tetraborate tetrahydrate( K2B4O7.4H2O )- a hydrated tetraborate salt of potassium.
  • Disodium molybdate( Na2MoO4 ) - a corrosion inhibitor, and non-oxidizing anodic inhibitor.
  • Sodium nitrate ( NaNO3 ) - a common preservative.
  • 2,2′,2”-nitrilotriethanol - a corrosion inhibitor.

Can inhibitor remove the sludge?

The inhibitor just breaks the sludge down and makes it easier to get it out of the system. It is necessary to make sure you have a magnetic filter installed in your heating system to catch any loose sludge and rust. To be able to remove it, you need to install a filter. The filter catches all the particles and stores them until your next boiler service, when you can get the filter emptied. In the absence of magnetic filters, loose sludge and rust can block narrow or lower bends in pipes. Loose sludge and rust makes water thick and increases the chances of the boiler breaking down. Therefore, having a magnetic filter before adding an inhibitor is important.

In an optimally running system you would top up your inhibitor every year, which could potentially keep your system clean and serene for 8-10 years.

The benefits of central heating inhibitor.
  • It does prevents debris and corrosion throughout your system, helping to prolong its life.
  • In the long run, you’ll save money on expensive new boiler parts. Without using inhibitor, your system could experience more faults and blockages – or break down completely.
  • Radiators warm up much quicker and the whole system is more efficient.
  • British Standard (BS 7593:2019 requires to have inhibitor added to new installation. Same way manufacturer also require inhibitor added before commissioning of the system.

Years of built-up sludge.

In old properties, the boiler, radiators and pipes don’t quite need replacing, but you don’t know how old they are, you’d be forgiven for assuming that you can simply use inhibitor to flush out the system. However, introducing inhibitor after years of sludge forming, is asking a lot of it. Rather, you will need to give your radiators a power flush, and then add the inhibitor afterwards to prevent sludge from building up and creating havoc in the future

How to add inhibitor to your central heating system.

This is a pretty simple task that anyone can do – you’re going to add the inhibitor to one radiator in your system (you only need to choose one). If you haven’t done this before, just follow the steps below. We’ll start with a general guide for combi boilers, which most of us have here in the UK.

Tools you’ll need:
  • Your chosen brand of inhibitor (see below for our recommendations)
  • Adjustable spanner
  • Hosepipe (will need to reach from your radiator to an outside drain)
  • Jubilee clip
  • Radiator key
  • Flathead screwdriver
  • Towels (to catch any drips or leaks)
  • Funnel and flexible tube to add inhibitor into radiator (although most inhibitor bottles come with a dosing adaptor so you probably won’t need this)

The following instructions are for a conventional radiator. If you have a towel radiator, turn your heating off and let it cool, then remove the plug on the top of the radiator and pour your inhibitor in.

Turn your central heating off

Let your radiators cool down completely.

  • Connect your hosepipe to your chosen radiator’s drain valve, drain the heating system partially. In general, draining 10-20 litres of water from 100 litre heating system is sufficient.
  • Choose the radiator or towel rail which is located at the most height point in your heating system. Use your adjustable spanner to unscrew the radiator or towel rail bleed plug.
  • Attach the inhibitor dosing adaptor - If your inhibitor comes with a dosing adaptor to attach to the radiator bleed plug, attach it now. If not, use a funnel and a flexible tube.
  • Pour in the inhibitor in.
  • Remove the adaptor or funnel, Tighten the bleed plug back on with your adjustable spanner.
  • Check your boiler pressure and top it up if needed
  • Now bleed your radiators, bleeding your radiators will make things much more efficient while the inhibitor circulates around your central heating system.