Flushing Your Central Heating System

When your central heating system starts to cause you problems, you may be experiencing some of the following:

If you have symptoms like those above then it could indicate that you need to flush your central heating system.

Below is an image that shows how the build-up of sludge and other debris causes your heating system to become deficient

When your central heating system collects so much sludge and debris, it slowly begins to deteriorate, to the point that it causes you much inconvenience. To fix this you have a couple of options:

Please read on to see how to do it yourself, but if that deters you and you feel you'd benefit from our expertise in flushing central heating systems, then see how we flush central heating systems.

If choosing to do it yourself, you will need a few basic tools:

Turning the water supply off

Firstly the water supply to your boiler system will need to be turned off and then the boiler itself will need to be switched off as well as the water heating pump. Once this is done, the water storage cistern of the central heating system will need to be modified in order to prevent it filling up. The basic process of this is taping the ball valve down so that it isn't afloat, preventing the system from filling up.

Draining the radiators

Next your radiator will need to be drained. This can be quite a long process if not experienced, which involves emptying the radiator by removing the valve caps at either end of the radiator and ensuring that they are closed. When this procedure is being completed, ensure the pipes are covered to prevent them being damaged and lay something on the floor around the pipe to protect your carpet. Then, using a hose, or a flushing machine, water needs to be pumped through the radiator, removing any sludge and debris that is causing the issues within the radiator. Ensure a bucket of some sort is placed where the dirty water will be coming out, otherwise your floor will be ruined.

Flushing your boiler

Your boiler will then need to be flushed, cleaning out any murky water that may be affecting the system. Corrosion inhibitor will need to be added to the water system to clean through all of the pipes. Before turning the water supply back on, your radiators will need to be bled, which involves removing any trapped air that may be in the pipes. Once this is completed, you are then able to turn your central heating system back on, and all should be working perfectly. Flushing your central heating system will take at least 4 hours to complete, but depends on how many radiators you have in your home, how confident you are, and how much sludge and debris is in the entire central heating system.

Call in the experts

We make the whole process a lot simpler. You don't need to know the technical ins and outs – you're just interested in getting your central heating system working nicely again. We live and breathe central heating systems and have years of experience in flushing central heating systems in a way that is faster, more efficient, and avoids any mess. We fully understand that your carpets, floors and nearby walls are essential to keep in perfect condition and we leave them exactly as we find them after the central heating flushing is complete.

In the first instance you should contact us to describe your symptoms because it may not be necessary to flush the whole system and we're happy to give you initial telephone advice before you're committed to anything.

Costs for us to flush your central heating system vary depending on the size of the installation but typically would range from:

We will also contact you months after the work has been completed to ensure that you're still completely happy with your flushed system.

Here are a few positive testimonials from happy clients that have used us to flush their central heating systems …

Great & speedy job just before the snow. Thanks OBS helped as out before the unexpected snow down.


Jill Morris, Kensington  

You did a fabulous job, thanks. We appreciate the extra effort you put in to make our boiler system work.


Mr & Mrs Dainton, Middlesex  

Excellent job all round. (Gas works & Power Flushing - Boiler Installation with Power Flushing).


Ms Fernandez, Isleworth, Hounslow  

Thank you for explaining how radiators work in plain English. After moving into the house in the Summer we had no idea that the radiators hadn't been serviced and were running poorly. Now that you've flushed the system through.


Paul Norgate, Wembley  
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