This gas boiler was struggling to heat the central heating system. Surprised? This issue is common in the plumbing and heating industry and can be detrimental to the longevity of our high-efficiency boilers being installed nationwide. Even the best boiler on the market won't last its recommended lifespan if your system is full of dirty water. So, what is sludge and scale?
What is Sludge ?
Sludge is a semi-solid slurry produced in the system due to corrosion. It's a mix of water, air, and loose corrosive metals. The abrasive nature of sludge can lead to premature pump and motorized valve failure. When sludge accumulates beyond what the boiler water can carry, it settles on boiler surfaces. This sludge film acts as a heat insulator, reducing heat transfer to water and making it take longer for the boiler to reach its set temperature.
Hardened sludge is very difficult to remove, requiring mechanical machines and chemicals to break it down and flush it out of the system.
What is Scale?
Scale is a hard mineral coating and corrosion deposit made up of solids and sediments from calcium and magnesium when heated. The level of dissolved solids in our water determines water hardness. Hard water is high in dissolved minerals, primarily calcium and magnesium.
Scale is a metal salt and a good conductor of electricity. When it builds up on metal surfaces inside boilers or central heating pumps, it acts as an anode, with the metal becoming a cathode. This anode-cathode setup allows electrons to flow freely between the scale and the metal, enabling corrosion. Since scale is not uniform, the corrosion becomes localised rather than spread evenly over the metal surface.
Sludge and scale can significantly affect heat transfer performance. Just 1 millimetre of scale or sludge can add 7.5% to energy costs, while 1.5mm adds 15%, and 7mm can increase costs by over 70%.
Precautions to Reduce the Risk of Sludge and Scale
Regular System Flushing: Periodically flushing your central heating system can help remove accumulated sludge and debris, preventing it from building up and causing issues. See our post on - How to Clean the Central Heating System
Use Inhibitors: Adding corrosion and scale inhibitors to the system water can prevent the formation of sludge and scale. These chemicals create a protective layer on metal surfaces. See our post on - BS 7593:2019: The Code of Practice for Domestic Heating and Cooling Systems.
Install a Magnetic Filter: A magnetic filter can capture and remove metal particles from the water, reducing the amount of sludge formed from corrosion. See our post on - Filters for your Central Heating System.
Install a Microbubble Deaerator: The primary advantage of using microbubble deaerators is their ability to remove even the smallest air bubbles and circulating air. See our post on - The Role and Functioning of Microbubble Deaerators in Central Heating Systems.
Water Softening: For areas with hard water, installing a resin pre filter can reduce the amount of calcium and magnesium in the water, preventing scale build-up. See our post on - VDI 2035 Water Treatment in Heating Systems.
Regular Maintenance: Schedule regular maintenance checks with a professional to ensure your heating system is clean and functioning efficiently. This includes inspecting and cleaning components like heat exchangers, pumps and radiators. see our post on - Unlock the Potential of Your Heating System with a Powerflush.
System Monitoring: Use monitoring systems to keep an eye on water quality and system performance, allowing for early detection and rectification of any issues.
We understand all central heating systems and the best methods for reducing heating bills, keeping families warm when it matters most, and maintaining boiler efficiency. Contact us for more information