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Speedy Gas LondonPowerflushing: The Only Guide You Need

Powerflushing: The Only Guide You Need

Something that will inevitably happen to your central heating system is the build up of sludge, which will block pipes and prevent radiators from working properly. The problem does not only lead to inefficiencies in the system, but also to higher costs: fuel bills will certainly be more expensive (the water system can waste 20-30% of the fuel used). Some people have their boiler serviced regularly, but forget that there are other important components subject to breakdown.

Do you need powerflushing?

This infographic will help you evaluate whether you need a powerflush or not. Have a look at the heating system and answer the following questions. Keep in mind that a powerflush will anyway improve its efficiency even if not extremely necessary.

Sludge: 5 different types

You probably don’t know that there are several different types of sludge. Depending on the age of the heating system and the materials it is made of, we can have:

Black Sludge

Generally found in 5+ years old heating systems, this type of sludge is the most common and it affects both the hot water efficiency and the performance of radiators. This general inefficiency leads to more expensive fuel bills.


Limescale Pellets

A serious problem when found in header tanks (loss of efficiency and probably boiler noise). Some people think this is gravel, but it’s not. Limescale pellets need to be removed in order to improve efficiency.


Brown Sludge

Also called fresh sludge, this kind of sludge is the one on its way to becoming black. Your heating system is making rust and needs to be powerflushed as soon as possible.



Very common with plastic piping and radiators fitted more than 10 years ago. If the pipework’s size is 10 millimiters it can block ‘solid’ when allowed to ‘rest’ over a summer period.


Sheet scale

Scale definitely increases energy consumption (this is due to 5-10 extra mm between the waterway and the flame).



The powerflushing solution

In order to fix heating circulation faults and disturbing boiler noises / radiator leakage, powerflushing is required. It should only be carried out by Gas Safe Registered Engineers and use the latest powerflushing techniques.

How does it work?

With powerflushing the whole central heating system will be cleaned without taking off the radiators. Thanks to a special substance added to the system water, powerflushing will start to loosen the rust. While technicians turn on radiators and make sure there are no cold spots, the sludge gets easily removed and collected with a magnet filter. It’s essential that the powerflushing continues until water samples are 100% clean and (also important) pH neutral. Adding a corrosion inhibitor to the water is the last step of the process and prevents future problems. Main benefits:

  • Higher temperature (radiators and hot water)
  • Fuel bills reduced by up to 50%

Powerflushing technology

In order to do a professional and thorough job, your heating company should use modern technology. Powerflushing requires a great deal of attention and expertise, but equipment is essential:

  • Digital water analysers
  • Digital thermometers
  • Maganclean filtration

Powerflushing Chemicals

In order to perform a powerflush, a number of chemicals are needed. In each phase of the process there is a particular chemical substance and product which contributes to the overall cleaning and repair of the heating system. Here is a list of them:
1. System precleaner

In case of new heating systems (or modified ones), chances are you can find installation debris and solder fluxes residues, copper swarf, casting sand, grease etc. A system precleaner disperses contaminants and dirt, passivates metal surfaces and prepares the system for maximum protection.

2. Flushing and Descaling Liquid

The flushing and descaling liquid starts to work immediately upon addition to the system and makes it possible to do a complete powerflush in a limited amount of time (one visit). Due to gradual decay, sludge, rust and other deposits accumulate over time: this liquid will mobilise these undesired substances and solve circulation problems leading to cold spots, boiler noises and pump failures.

3. Corrosion Inhibitor

A very important part of the powerflushing is the addition of the corrosion inhibitor to the clean water. This is a chemical compound that basically decreases the corrosion rate of metals/alloys by forming a coating that prevents access of corrosive substances to the metal that needs to be protected.

4. Neutralising Crystals

In order to neutralise acidic flushing chemicals, neutralising crystals are circulated to ensure a thorough neutralisation of any trace of those substances and make your heating system completely safe.

5. Boiler Noise Silencer

Limescale doposits and corrosion cause boiler noise problems. Whilst powerflushing may solve this problem, some types of heating systems could still be susceptible to the noise issue. To have the heat exchangers cleansed, the addition of a “boiler silencer” chemical is recommended to restore efficiency and remove noises.

Check yourself

In order to better understand the situation and evaluate the type of service you need, here is a 7-step guideline to check your heating system by yourself:

  • Inspect the boiler flame. You should NOT remove the boiler casing, but make sure the flame is blue. Is it yellow? Call us for a professional gas engineering inspection.
  • Pass the palm of your hand over the radiators to find cold spots: this is a clear sign of sludge in the heating system.
  • Get a water sample from one of the radiators (use the radiator key to open the bleed valve). Is the water gray, brown or black? You probably need a powerflush to remove unwanted substances.
  • Radiator valves: corroded or leaking? A replacement is needed.
  • Do you smell gas?
  • Listen carefully to be aware of noisy pipes (generally due to limescale, sludge)
  • Do you have a constant supply of hot water from your combi boiler? If intermittent, descale needed.


Powerflushing prices

In order to know the exact price for your full home powerflush service you should ask  your plumbing and heating company for a quote. Prices will vary according to the number of radiators. Speedy Gas service prices range from £280.00. Request today a free quote: call 020 8123 9211


People often have doubts or questions about Powerflushing. Here the most common questions and their answers:

How long does a powerflushing take?

The answer to this question depends on the size of the system we will powerflush. It generally takes 5+ hours to complete the job, but it can require more time if additional work is needed, for example something related to radiator valves.

Is powerflushing safe?

It is important to mention that powerflushing should be only carried out by qualified professionals. Only eco-friendly powerflushing chemicals should be used.

Does powerflushing really reduce fuel bills?

Yes, improving the overall efficiency of the heating system means also reducing costs. When undesired substances accumulate over time, the system will require more energy (thus, more fuel) to reach a certain temperature. Removing those substances leads to cheaper heating.

Where we go

Speedy Gas covers all of North London, NW, East London & Central London and surrounding districts. We can provide references from clients across London who we have provided boiler installations and heating / plumbing services to in the last year.

Get in Touch Today!

Mob: 078 1728 8668
Email: info@speedygaslondon.co.uk