Cartoon of Frank Lever, The Boiler Repair Man by Penwin

Frank The Boiler Repair Man

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Does my central heating system need to be power flushed?

If you are replacing your boiler but keeping your old radiators it is considered best practice to power flush your radiators and pipes to remove built-up debris.

In the event that you are not replacing your boiler you might consider power flushing your central heating system where you suspect or experience any of these common problems noted below:

  • System slow to start up
  • Boiler cutting out due to damaged or blocked pump
  • Frequent pump failure
  • Loud banging noises from your boiler 'Kettling' noises
  • Cold spots in radiators either at the top or bottom.
  • Radiators that need frequent bleeding
  • Radiators with pin hole perforations and leakages
  • Dirty discoloured water in the radiators
  • Noisy pipes due to restrictions
  • Blocked pipes and valves due to sludge or lime scale

The benefits of power flushing your central heating system:

  • Possible savings on your fuel bills
  • More efficient quieter system
  • Better circulation and faster heat up
  • Rust and lime scale protection

Brief explanation of power flushing objectives, the method used and its limitations Power Flushing is regarded as best practice within the plumbing profession for providing an efficient and effective method of cleansing the central heating system.

The objective of power flushing is to restore your system with circulation and soften boiler noise caused by sludge and corrosion deposits. Specialist chemicals are used to loosen then mobilise any scale deposits in your pipes and radiators, effectively removing stubborn coatings to the inside of your system and flushing them out.

The chemicals used to power flush your system will be chosen to suit its exact requirements. It will be cleansed methodically and thoroughly. Once your whole system has been power flushed we will refill it with clean water, and a corrosive inhibitor will be added. Information about all of the chemicals used during this process will be noted on to your boiler front cover to protect the boiler warranty.

The process is time consuming usually taking a day to complete, but the timing depends on the number of radiators and the type of system you have. The success of a power flush will depend on the level of corrosion which has occurred beforehand. The process will cure most circulation problems, but cannot undo the corrosion and gradual decay that has led to the need to power flush the system.

While it is rare for a heating system to experience leaks after the power flushing process, it is not possible to inspect a system internally beforehand, and the need to use a flushing and dispersing chemical for effective cleansing means that occasionally we may find a leak. The advanced stage of corrosion required for such a situation means that the leak would occur, imminently even without a power flush. It is perhaps better that it occurs whilst plumbers are present to remedy the problem.

Systems which have been neglected over a period of time, or have not been treated with an effective corrosion inhibitor, may have severely compacted corrosion debris in the pipe work, radiators, or boiler, and it is possible that even after the power flush, some radiators may still not be fully effective or boilers on the margin of failure may cease working due to sludge and debris later breaking loose and collecting in the heat exchanger.

The price quoted for a power flush allows for a standard power flush only and if any of the above or similar problems arise during or after the power flush the company cannot be held responsible. Any further work required would need to be carried out at an additional cost.


The price of your power flush is simple to calculate we charge a flat fee of £200 plus £25 per radiator on your system. As an example it would cost £325 for a house with 5 radiators.

Photo of Frank performing a power flush.