Due to the chemical reaction that occurs between the different metals in a given boiler/system, aided by the water and any air that may be present, a substance called magnetite is produced, taking the form of “sludge” and metallic flakes. This magnetite can block components in your boiler and system, speed up further corrosion and make your system less efficient as the boiler has to work harder to heat the dirty water. You may also find that your radiators get hot at the top while the bottom remains cold (although a couple of other things can cause this symptom too).
- Powerflushing is where a special pump is connected onto your system and heated water containing strong chemicals is forced around it. Each radiator is turned on, one at a time, and vibrated at it’s low edge using a special hammer drill attachment to dislodge any sludge and particles. This dirty water is then purged to a drain and the system refilled with clean water, along with a chemical inhibitor to slow down the corrosion process in future. Powerflushing a system of up to 7 radiators is £400 (£30 per additional rad). Powerflushes are more suited to open-vented systems (those that have a small header tank, usually in the loft).
- A cheaper option for systems that aren’t so severely sludged, and a better option for sealed/pressurised systems (no header tank), is to have a Chemical Cleanse. Here, we attend, drain your system and add a chemical cleaning agent before refilling. You then continue to use your system as normal for 1 – 2 weeks while the agent sets to work dislodging the sludge and particles. We then return after that time to drain out the dirty water and refill with clean, again adding an inhibitor. A chemical cleanse can be carried out for £180.
- As a further preventative measure, you might also like to consider having a magnetic filter fitted – see also Money-Saving System Upgrades, Magnetic Filters.