Power flushing: cleaning sludge from your radiators

It’s important to keep your radiators working properly, so they can keep you warm through the winter. If you’re having problems with your heating, your radiators might need a power flush.

There are several symptoms that show you might need a power flush.

  • Some radiators are completely or partially cold

  • Radiators need frequently bleeding

  • Repeated pump failures/corrosion deposits in pump casing

  • `Kettling' and banging noises from the boiler

  • Long recovery time after drawing off hot water

Sludge might also be to blame if some radiators aren’t warming up while others work properly. 

You’ll find information below about the causes of sludge in your central heating system. We’ll also explain the power flushing process.

   Why is there sludge in the radiator?

The older your central heating system is, the more likely it is you have sludge in your radiators.

Blocked radiators make your bills higher, as your heating has to work harder to warm your home. Sludge can also damage your boiler, heat pump and valves.

  1. Radiator sludge is a mix of dirt and rust. This builds up over time and gathers at the bottom of your radiators. 

  2. The sludge stops hot water flowing through your system properly. This creates cold areas on your radiator. 

  3. Other areas of the radiator are unaffected by the sludge and warm up as normal.


  How does power flushing work?

If you think you have sludge blocking your radiators, get a Heating engineer to have a look.

If you need a power flush, the engineer will connect a machine to your system. This will push a powerful, low pressure flow of liquid through your system. This dislodges sludge and rust, removing it from your radiators,pipes and boiler.

It can take several hours to flush out your heating system. It can take even longer if you have a larger system or there’s a lot of sludge.

It is important that the cleaned central heating system is treated with the chemical inhibitor immediately following  cleaning. The inhibitor will minimise the corrosion of metals within the system and also protect against  the formation of limescale. This will ensure that design energy efficiency is maintained, replacement of components due to corrosion and erosion is minimised.


BS EN 12828 and BS EN 12831 Hot water central heating system for domestic premises England, Wales, Scotland, Northern Ireland and Republic of Ireland.

BS 7593: Code of Practice for treatment of water in domestic hot water central heating system 


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Sammar Services Ltd

13 Stanley Road



Tel: 07516394466

Gas Plumbing & Electrical Ltd incorporated in England number 10017055

Sammar Services Ltd


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