Radiators rust internally producing a black iron oxide ‘sludge’.  This sludge/ corrosion product moves around the heating system blocking pipes, valves, pumps, heat exchangers, valves etc, and internal components within the boiler.

Cleaning a central heating system is integral to its’ health and efficiency.  There are a few types of cleaning methods including chemical ‘power-flushing’, which is popular due to the rapid but comprehensive clean it can deliver.  Some elderly systems require a slower and more methodical type of clean to alleviate any risk of pipe joint failure which can occur during a ‘power flush’ type clean.

The benefits of a clean heating system include those below:

  • More even heat distribution throughout the property
  • Improved overall energy savings
  • Lower household bills
  • Increased system reliability
  • Extended system life

So how do you know if a system needs a chemical system flush? 

Here are some symptoms to look out for:

  • Are certain rooms much colder than others?
  • Does it take a long time for your system to warm up?
  • Are one or more radiators cold at the bottom and hot at the top?
  • Do your radiators need frequent bleeding?
  • Is the boiler noisy?


In addition to the benefits mentioned above, the Compliance Guide to Part L of the UK Building Regulations for England and Wales requires a central heating system to be cleaned and flushed before a corrosion and scale inhibitor chemical is added during commissioning. It’s also prudent to do this when an old central heating boiler is being replaced by a new boiler.

Many Boiler Manufacturer’s now make the warranty dependent on flushing and cleaning in accordance with BS7593, Benchmark and Part L, so if boiler component failure is due to sludge not cleared at point of install, the warranty may not be honoured.


A Ward Gas Services Engineer will attend your property on a free of charge visit to fully assess your system and discuss the issues you are experiencing.

An estimate will be provided for the best course of action in chemically flushing your system, and any associated work which may be recommended to be undertaken at the same time.
You are one step away from a more efficient warmer home, so contact us today to arrange a convenient, no obligation estimate visit on 01903 239709

…and if you need to see evidence…..

Sludge!! Removed from a system