The Guide to Good Central Heating

The Guide to Good Central Heating

December 6, 2018 7 By Nicola Litchfield

You can be forgiven for not knowing, or not realising, that our central heating systems need cleaning every now and then. Over time, our central heating can become clogged up and blocked, reducing the overall efficiency and reliability. This is crucial as an unkempt system can impact the amount of energy used when heating your home, and your heating bills!

It can be easy to forget about our home appliances that work day-in day-out, but it’s important to remember they need servicing. Especially in the winter months, making sure your boiler is in tip-top condition could save more than just a cold shower. In this post, we’ll give you some tips about flushing your system, and some great products that will keep things running smoothly.


First, here are some signs to look out for that can indicate your central heating needs some TLC:


Slow Starter: If your heating takes quite a long time to get going, and for a bath you need the water warming well in advance, it could be a sign your boiler is working too hard. Also, if your hot water tends to run out very quickly, it would be worth flushing through your system.

The Sludge Test: If when you bleed your radiator, the water is brown, this indicates that sludge* is building up in your system. Sludge can seriously clog things up preventing the water from flowing around freely. This will make your boiler work harder and your system weaker. If the water is dark brown you should act ASAP to remove the sludge and a power flush may be required.

*Sludge is tiny fragments of metal and dirt. As time goes on your radiator and system will rust and sludge will start to accumulate.

Hot & Cold Spots: Another sign that your system is becoming clogged up is cold spots on your radiator. This is again due to sludge building up in your radiator preventing the water from making the rounds. This can also result in uneven heating within your rooms.

Blaring Boiler: When a boiler is making an awful lot of noise, it tends to mean something is amiss. This could be due to it working extra hard or because of the dreaded sludge is getting into your boiler (which you really don’t want). Always address this as an overworking boiler can cost energy and money, not to mention it won’t be heating your house properly!

Before we get onto how to bleed you radiators, here are some great products that can help to keep your system efficient and healthy. They are essentially cleaners and can make the world of difference if your heating is letting you down.



These cleaners are a cost-friendly way to cleanse your system of dirt, rust and limescale. They can improve your heating efficiency and stop the boiler from barking.

Adey MC3 Cleaner   

Fernox Central Heating Cleaner (500ml) F3



Inhibitors are perfect for getting rid of contaminants and for protecting your heating in the future. They prevent the build-up of sludge, limescale, battle against corrosion, and extend your systems running life.

Fernox F1 Central Heating Protect 500ml

Adey MC1+ Protector Liquid 500ml


Magnetic filters are great to ensure your systems health over an extended period. They attach to your boiler and as the water runs through, the fragments of metal are grabbed by the magnet preventing build-up elsewhere. They are easy to install and can reduce your annual heating costs by up to 6%*

Adey MagnaClean Professional 2*

Fernox TF1 Compact Magnetic Filter 22mm


Give it a Flush

Using the products above are great for keeping your system clean and for preventing future build up. However, if the sludge has gone too far you may need to flush your radiators. This can be a little time consuming however it is absolutely necessary to ensure your system keeps working.

Please note the below guide is to flush your radiators, not your whole system – that requires a power-flush.

  1. Turn your heating off and let everything cool down so you don’t burn yourself.
  2. Get some old sheets together – These will be needed to catch all the sludge, make sure they are positioned under your radiator valves.
  3. Switch your valves off – This is to isolate your radiator from the rest of the system. This is essential, or you will have water everywhere. Start by turning off the thermostatic valve by turning it to ‘0’ or ‘off’. Then at the other end of the radiator, remove the plastic cap or lockshield from the valve. Then, turn the lockshield valve a full turn clockwise,  make sure you count the number of turns needed. After this, with two wrenches, loosen the thermostatic valve. One on the body of the valve to create resistance, then loosen the nut that connects the radiator and the valve with the other wrench.
  1. Disconnect the radiator – Now you will be able to remove the radiator, careful, water and sludge may glug out (make sure you have suitable sheets down and floor protection). Take it outside and give it a flush through with a hose, keep going until the water is totally clear.
  1. Reconnect – To get your rad back on the wall follow these steps in reverse order. When reconnecting it may be worth getting some inhibitor through your system to protect your fresh new radiator.