Sludge Busters!

A quick guide on how to identify if you have magnetite in your central heating system and the solutions on how to fix it!

Most people know, if your radiators are cold at the top and warm at the bottom they usually just need bleeding. A simple process where you turn the valve slowly and let any air out of the radiator so the water can get to the top. But what if you have a build up of magnetite in your system?

What does it mean if your radiator is hot at the top but warm at the bottom?

This could be a sign of magnetite building up in your radiators which could lead to costly problems, particularly if it reaches the inside of the boiler! Magnetite is sediment that collects in the heating system over time, which can potentially damage pipework, boiler and heating components and radiators.

Signs of Magnetite Build Up

Other signs of magnetite building up in the central heating system may be;

  • Radiators not getting as hot as they used to
  • Increased gas bills
  • Boiler making kettle sounds
  • Rust on your radiators
  • Black inky substances coming out of the radiator when they are bled


To solve this problem, there are a few solutions. Please note, all of these should be completed by a qualified professional. 

  • Firstly, a magnetic filter can be added to your central heating system. This attracts the magnetic sediment and stops it from reaching your boiler. This is vital as if the boiler components are damaged, this is likely to be the most costly to repair!
  • A central heating chemical flush can be completed. This is where chemicals are added to the central heating system to loosen any build up and are then flushed through all of the radiators and emptied out. If they are particularly bad, thick black sludge will come out!
  • A magnetic flush can be completed. This is when two extra strength magnets are attached to the central heating system to extract of the magnetic sludge built up in the system. The picture below highlights what can often be taken from central heating system when completing a magnetic flush.
Magnetite Build Up

These are just some of the options that are available, for solutions tailored to your own heating system, feel free to give us a call and we will be happy to talk through it with you. 

What to do if you think you have a build up of magnetite in your system?

Here are a few tips if you think your system may be getting clogged up with black sludge!

  • When you next book an appointment with a plumber, ask them to do a water test of your central heating water. The colour will show the water quality in the system.
  • Book an appointment with a plumber for them to give you a quote to rectify any issues you may have. If the problem is caught early it easier to solve!
  • Turn on the heating and turn off all of the radiators aside from the problem radiator. Check to see if this radiator gets hot. Slowly turn all of the other radiators back on. If the radiator stays hot, the issue was air and the problem is solved! If not, there may be a blockage in the system!


The DTS Plumbing Team

Moving Home – The Plumbing Guide

New home?

Are you buying a new home and not sure what telltale signs to look for that the plumbing just isn’t quite right? This blog tells you what to look for when buying a new home and explains in detail our new homeowner survey, which may help you pick up a few top tips!

Signs of Plumbing Issues

  • Look for damp or browning patches on ceilings or walls. Pay particular attention to those directly below the bathroom and boiler, if it is located upstairs.
  • If the sealant around the shower, bath or sinks is black and looks like it is coming away from the wall, there may be a leak that has not presented itself yet.
  • Check under the kitchen sink. If the cupboards are showing signs of damp or water damage, it may be that a pipe behind the unit is leaking, which may be a costly repair if it has been leaking for a long time!
  • Turn on the shower. It may seem another strange thing to do but it can highlight if there are any issues with the water pressure in the property and whether there are any underlying issues that may crop up in the future.

Signs of Central Heating Issues

  • Check that the radiators aren’t showing any signs of rusting, either on the panels themselves or on the valves at the top and bottom. Rusting on the valves may be a sign of a leak, the current homeowners may have already had this fixed but it’s always worth checking! Rust on the radiators themselves can be caused by a variety of things, but may lead to needing new radiators or even a full central heating powerflush.
  • They may find it strange, but ask the current owners if they wouldn’t mind turning on the heating. A new boiler is a big expense and one that most people don’t want to worry about when moving in to a new home!
  • Does the boiler look in good condition? It isn’t always possible to tell to the naked eye but the main things to look for are signs of rust or water marks around the boiler area, the boiler being intact including the case and surrounding panels being attached correctly and that the boiler has been serviced regularly, for which the engineer should have provided a certificate.

How We Can Help

We have designed a plumbing audit to carry out on your current or new property to ensure everything is running smoothly and you wont encounter any nasty plumbing surprises! This includes:

  • Boiler and hob gas safety check
  • Radiator health check – ensure all radiators are getting hot when tested
  • Thermostat is working correctly, safely and is in good working order
  • Test all taps to ensure they are in working order and hot and cold water is running
  • Test all valves throughout the central heating – this includes zone valves, radiator valves etc
  • Visual check on all central heating pipework to ensure this is in good condition.
  • Visual check on all basins and sinks to ensure they are in good condition and that there are no visible leaks when water is drained.
  • All toilets are flushing, are in good working order and have no visible leaks.
  • All showers are in working order, there are no visible leaks and hot and cold water is available.
  • A written report to explain findings and give any recommendations that may be needed.

Plumbing audits start from £100. This may increase due to a higher number of gas appliances, radiators and the size of the property. 

For more information, contact us on 0114 2483011 or at For more handy tips, visit our Facebook page: