What you need to know about sludge – the unwelcome gatecrasher in your central heating system
Sludge is a devious houseguest. You don't realise it has taken residence in your heating system until you find that your radiators aren't getting so warm all over or. worse still, your boiler breaks down because its components and pipes are all clogged up.
Forewarned is forearmed, though, so here are few things you should know about sludge, including how you can banish it and prevent it in the future.
Sludge, AKA magnetite, is made up of tiny magnetic particles that can build up quickly in untreated heating systems. They float around in pipes and radiators until they eventually reach the boiler, clogging up components and eventually causing the boiler to breakdown.
Sludge settles at the bottom of radiators and prevents the heat coming through properly. That’s why your radiators may feel cold in places, even if when your heating is turned up.
If you’re continually turning your heating up but not feeling a real difference, it could mean that sludge is blocking your system. And when you’re turning your heating up, you’re using more energy to try and get your home to a comfortable temperature. And that means higher energy bills. This is not good news at a time when we are all doing our best to reduce our energy bills!
A central heating system contaminated by sludge must work harder to pump water around, using more energy to make the room feel warm enough. If your system is sludge-free it will use less energy and can reduce your carbon emissions by up to 7%*.
Most UK heating systems are not protected against sludge – but now you know the facts, you can make sure you’re not one of them!
Your Gas Safe registered heating engineer should know all about some important changes that were made to the Building Regulations in 2022 to help combat sludge. Now, they must fit all new boilers with an inline magnetic filter, flush and clean out the heating system and add scale and corrosion inhibitor. And they should test the water in your heating system during every annual service, to check it has the right amount of chemicals to prevent the sludge from forming, as well as clean any sludge that has been caught in the magnetic filter.
And if you don’t have a filter fitted to your existing heating system, ask your installer to fit one for you!
These thermal images of radiators show how the sludge (darker patches) is preventing the heat (yellow) from spreading across the whole radiator and warming the room.
*Independent research by ADEY alongside KIWA GasTec and Delta EE
**Against a corrosion filled system