Sludging in radiators: What is the Solution and frequency?


De-sludging radiators is a recommended maintenance measure for certain types of radiators. This practice is generally recommended to extend the life of devices and avoid loss of performance over time. But is it really useful? What sludge removal really is? When, why, and how to practice it? What will be the cost when calling a professional? Our responses in this dossier.

What is radiator sludge removal?

While removing sludge from radiators is a common and recommended practice, not everyone knows exactly what it is. Sludge removal is a cleaning action that aims to eliminate the sludge that naturally accumulates in radiators.

This sludge is formed over time by an accumulation of impurities, lime, bacteria, and by the corrosion of metals which gradually oxidize in contact with water. This sludge is deposited in the lower part of the radiators, this is called sludge. However, stored in this way, they interfere with the proper functioning of devices which lose performance and wear out much more quickly. It is important to know that sludge hinders the performance of the equipment and can lead to overconsumption of energy in the order of 10 to 20%! Sludge removal therefore simply consists of eliminating this sludge.

Obviously, not all types of radiators are affected by sludge removal. It applies to systems that operate through a hydraulic central heating circuit. This, therefore, applies to boilers (gas, oil, wood, and pellet), heat pumps, and combined solar systems.

There are two techniques for sludge removal:

  • By machine: this machine sends pressurized water into the circuit to defog the radiators.
  • By product: a sludge removal product is injected into the circuit and acts for 24 to 48 hours. It is used to loosen the particles of mud in order to allow them to be removed by rinsing or by emptying the radiators.

Why do you need to remove mud from the radiators?

As we have said, sludge removal is used to remove particles that naturally accumulate in radiators and form sludge. However, these muddy materials impact the efficiency of radiators, reduce their energy performance, and increase heating bills.

Sludge removal has many advantages:

  • It facilitates good water circulation in the heating circuits.
  • It maintains the good performance of the heating system.
  • It prevents the heating network from operating at full power to compensate for its lower efficiency due to the presence of sludge, which preserves its lifespan.
  • It allows energy savings of up to 15% on average.
  • It avoids the effect of premature wear of the heater.
  • Heating comfort is much higher.

In short, the sludge removal of radiators is indeed a useful and important procedure. However, it should be known that if the procedure is simple with the new installations, the oldest ones can be weakened, in particular when the accumulated sludge blocked certain leaks which must then be filled otherwise.

When should you remove mud from your radiators?

It is recommended to defog your radiators before the heating season, ideally during the fall. However, if the radiators are well maintained, it is not always worth doing it every year. Some pros recommend descaling a relatively new, healthy device every 5-10 years. An annual check is recommended mainly on old installations.

It is best to perform a test. Simply bleed your radiators and watch the fluid flow out. If it’s crystal clear, it’s clean water and you’re fine. If it is loaded with impurities or sludge, it is time to unclog the network. Likewise, if you notice that part of your radiators remain cool to the touch when they are in operation or that they are particularly noisy during their operation, it is that it is necessary to consider a sludge removal.

On the other hand, if you plan to install a new heating device on your circuit, we recommend that you carry out a preliminary sludge removal. This will allow you to start over with a clean circuit and avoid weakening your new boiler or brand new heat pump from the start.

How to disentangle your radiators?

Sludge removal can be carried out by you or by a qualified professional.

How do you defog your radiators yourself?

To properly remove mud from your radiators, follow these steps:

  • Bleed your radiators to remove accumulated air.
  • Start by emptying your heating circuit.
  • Close each radiator one by one.
  • Connect a garden hose to the faucet and open the boiler isolation valves.
  • Open the water supply at the other end of the hose and observe the condition of the water flowing. Wait until it is clear before you stop.
  • Your radiators are then clean and well defused. All you have to do is put the circuit back in place.

You can also use a sludge removal chemical to inject into the circuit. This will loosen the sludge and release the particles in suspension to better eliminate them during emptying.

Entrust the sludge removal of your radiators to a professional

If you do not wish to take care of the sludge removal of your radiators, you can entrust this task to a qualified and competent professional. Count between 400 and 800 euros to bring in a pro. The price varies from one company to another but will depend primarily on the size of your heating network and the technique used.


About Savi

Savi is a regular writer and social activist. She also writes for BBC, Huffington Posts and others.

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