This method is more of a stopgap and will only treat individual radiators and could leave sludge in your system so it’s not a long term solution but is a good alternative.

What tools do you need?

To remove and manually flush your radiators you will need:

• Old sheets and towels
• Radiator key
• Two adjustable wrenches
• Bucket or bowl
• PTFE tape
• Hosepipe and water supply

Guide to removing a radiator

This page has a detailed guide walking you though the actual process of removing a radiator. This can be done with one person but if it’s a large radiator then it may be worth getting someone else to lend you a hand. Most importantly make sure you follow all the steps and also take care to protect the flooring and carpet as radiator sludge is very very dirty.

Manually flushing a radiator

Once you have removed your radiator then ensure you have a container ready to pour the contents in. This will be the water that is always in your radiator but it will be black and dirty due to the sludge build-up. The sludge will stay in the radiator though so this is where the flushing is needed.

Carry the radiator outside to your garden and using a hosepipe flush clean water through the valve outlets on each side. This obviously hasn’t got the same pressure that power flushing has but it will do a good enough job to remove the radiator sludge. If you haven’t got a garden and perhaps live in a flat then you could always do this in your bathroom instead by putting the radiator in the bath, and then removing the shower-head attachment so that your shower is a replacement for the hosepipe. If you do use your bath then use an old sheet to prevent scratches on the bath and be prepared for some cleaning! See the image to the right!

Once you’ve flushed the radiator then you can reconnect it to your central heating system in a reverse of the way you removed the radiator.

A word of warning

This method is not very professional and if you have sludge in one radiator then it’s likely you have it in others so don’t view this as a long term solution. If left long enough then this sludge can make it’s way around your heating system and ultimately damage the boiler, heat pump and valves. If you have sludge in your radiators then it’s worth saving up to get your whole central heating system power flushed for around £300 and they will also add inhibitor to your system which should give your central heating a new lease of life.

When a radiator is full of sludge then the contents can make this job very messy so ensure that you’re fully prepared to clean up any spills but don’t let this put you off as if you do it right then you shouldn’t have a problem. Other items you will need are:

• Old sheets and towels
• Radiator key
• Two adjustable wrenches
• Bucket or bowl
• PTFE tape

1. Preparation

Make sure that you’ve turned your central heating off and let it cool down as you don’t want to be dealing with hot water when emptying the radiator. Next place the old sheets and towels under the radiator and especially beneath the valves and around the pipes coming through the floorboards.

2. Turn off the valves

Next you will need to isolate the radiator by turning off the valves on each end. First turn the the Thermostatic Radiator Valve (TRV) to it’s fully off position. At the other end of the radiator you will find the lockshield valve which will usually have a plastic cover over it. Remove the plastic cover and using an adjustable wrench turn the valve fully clockwise making note of the amount of turns it takes. You will need to reset the valve by the same amount when you replace the radiator to ensure it’s properly balanced. Your radiator is now isolated from the central heating system.

3. Loosen the thermostatic valve

Place a bucket or bowl under the thermostatic valve and using  both the adjustable wrenches, place one wrench over the body of the valve and use the other to loosen the nut that connects the radiator to the valve. See the diagram to right to an idea of what you have to do.

4. Open the bleed valve

Ensuring that you’ve got the bowl and the sheets below the valve you’ve just undone it’s time to open the bleed valve using your radiator key which will break the vacuum in the system and allow the water to flow out and into the bowl or bucket. This is when you get to see how dirty your water is and how much sludge is in your radiator.

5. Open the lockshield valve

Now it’s time to do exactly the same to the lockshield valve and you should be able to tilt the radiator to remove any excess water in it. Lastly use the radiator key to close the bleed valve which should reintroduce the vacuum in the radiator. You can now remove the radiator from the wall but be careful of any sludge leaking out the radiator so it might be useful to tape some sandwich bags around each of the valve ends.

To replace the radiator wrap PTFE tape around the threads and tighten the valves on each side.

This radiator sludge is a mixture of rust and dirty water most likely to happen to systems over 10 years old and in worst case scenarios can also damage your pump, boiler and valves, so it’s important to get this fixed.

What is power flushing?

Power flushing is basically a method of attaching a flushing unit to your central heating system which sends a powerful flow of fresh clean water through your whole system which removes the sludge and leaves you with a system full of clean fresh pH neutral water which reduces the risk of future damage to your system. This flow is sent at high velocity but low pressure meaning there is no damage done to your pipework. Chemicals will also be added to this stream which help loosen corrosion and hard deposits.

There is no need to remove radiators and the only mess is from the outflow pipe so this is an easier method than removing and flushing single radiators and will only take around 4-5 hours to complete.

It is also useful to get a corrosion inhibitor added to your system at this time which will help prevent the build-up of sludge in the future.

How much does a power flush cost?

This is not something you can do yourself and so you will need to hire a heating and plumbing engineer to power flush the system for you and this will set you back around £275-350 but as with hiring any tradesmen prices and services can vary so do your homework.

Power flushing will increase the efficiency of your heating meaning lower energy costs whilst also doing your bit for the environment so it is definitely money well spent and engineers recommend flushing your system regularly every 5 years to keep the system in tip top condition.