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System Cleaning

Keeping your Heating system clean is essential to a warm, energy efficient home

Did you know poor heating system water quality is the number 1 cause of boiler breakdowns?!

The water quality of heating systems has had a huge light shone on it recently with the longer warranties on boilers being void due to poor heating system water quality.

When a new appliance is installed the system should be flushed and then protected against future issues, weather this be to VDI2035 water treatment or inhibitor, 

We offer our cleaning and water quality services through Bedford and the surrounding areas.

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Below we have done a mini guide for Understanding and Dealing with Corrosion in Central Heating Systems.

What is meant by corrosion in a central heating system?

From the time of installation and commissioning a central heating system will, potentially, start to corrode. In fact, even new systems suffer from flash corrosion due to the inpurities of the water initially added.


This is because the water in the system will start to react with the steel in the radiators. To reduce the rate of corrosion, a plumber will flush out a newly installed system to remove any debris or substances likely to increase the rate or risk of corrosion such as flux or wire wool deposits.

A common symptom of corrosion within a central heating system is sludge, a black, mud-like, deposit resulting from the reaction between the minerals & oxygen in your heating water and the steel in the radiators.

The sludge can build up over a period of time in an untreated central heating system, and cause:

  • Damage to the boiler. 

  • Damage to radiators by causing pin holing and leaks.

  • Damage to the pump. 

  • Damage to the thermostatic radiator valves. 

  • Blocked pipework. 

  • Blocked and damaged hot water heat exchanger on a combination boiler.

  • System efficiency being reduced (less output from the radiators resulting in cold spots and cold rooms)

another common symptom of corrosion, not as easily seen to the eye is scaling due to the salt and mineral impurities in our tap water, used to fill our heating systems, these salts increase conductivity levels of our heating water and can cause big issues, such as scaling of boiler heat exchangers leading to efficiency losses.

Historically a system should have been well designed and installed by a professional heating engineer and flushed out correctly as part of the commissioning process, the water in the system should stay clean providing Desalinised water (VDI2035) or corrosion inhibitor chemical

was added after the flush and no maintenance or leaks have been carried out on the system.

If the system has been drained for any maintenance or repair and a corrosion inhibitor or VDI2035 desalinised water was not added when refilling the system, the system is again liable for problems with corrosion.

did you know filling your heating system with softned water is a no no!

the salts increase conductivity levels of the system and cause damage, especially to aluminium components.

At KP&H we have taken a different path and fill and flush the system using a chemical-free process, we believe that these chemicals cause more harm than good to the system and its components and see it as a lazy way to not clean the system properly.

We have adopted a method they use in Germany, and austria of using demineralised water, Germany has the standard of Vdi2035 as well as Austria has their own standard and some other countries do too. They all revolve around the same idea: You take the oxygen out of the water, keep the conductivity low and the ph level correct for the system components and you won’t have the ingredients for the corrosion to take place.

Here's how we protect your central heating system


  • We start off by taking reading off your system water and see exactly what is happening. 

  • Use a product called a Thoroughflush to clean the system and then check the system water against your tap water to see if the readings are the same and similar. The Thoroughflush gives us the ability to reverse flow through the system at the turn of a switch. And removes around 30-40% extra to what would be removed by just flushing in one direction. Each rad will be flushed individually, radiators may be removed if required and flushed externally, usually towel rails. 

  • A thermal imaging camera will be used to check each radiator to confirm they have been properly cleaned. 

  • When we are happy we will that we will fill your using with our resin and check the water again to make sure it’s within the ranges we would like. 

  • We would also recommend fitting an air separator and a magnetic and particle filter. 

  • Readings again will be taken after a 10-week period to make sure everything is ok. 

  • Yearly checks will then be advised and usually advised to do at the same time as your annual boiler service to reduce costs installs of two visits.

We also supply and fit resin cartridges that can be left on site for top-up and filling of system water.

want more information on VDI2035? here is the link to a great heat geek article 

Contact us for more information about cleaning your central heating system!

If you'd like to find out more information regarding system water and powerflushing, then please do not hesitate to contact us today.


 You can send us a message using our website's contact form or give us a call at 07478 848 834

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