Treatment and analysis of the heating water

Posted on 2026-04-07 | Chauffage

What issues can you face with water in a heating system?

Two well-known phenomena are at the origin of most failures or breakdowns in systems where water is the heating medium:

- Presence of gas (Hydrogen)
- Presence of black sludge (Magnetite)

What disorders can be created by these two factors?

Hydrogen

PROBLEM CONSEQUENCE
Corrosion of:
- radiators
- boilers
- expansion vessels
- faucets and valves
- fittings		 Leaks
Noise:
- in the whole system		 Inconvenience for the user
Gas (hydrogen) stays in the high sections of the installation, such as radiators. Water circulation stops. Heating decreases or can become null.

Black sludge

PROBLEM CONSEQUENCE
The black sludge stays at the bottom points of the installation, such as radiators. Water circulation stops. Boiler becomes noisy. Sounds in the whole installation system may lead users to fear an explosion.
In the boiler, water circulation slows down or stops. It starts to boil. Boiler becomes noisy. Sounds in the whole installation system may lead users to fear an explosion.
Sludge acts as a thermal insulator, preventing heat transfer. Heating decreases or can become null.
Sludge, of metal origin, is abrasive, wears rotating parts, or blocks them. Noisy or blocked pump and mixing valves.

Bacteria, algae and limescale

PROBLEM CONSEQUENCE
Development of bacteria and algae. Calcareous deposits. Heating decreases
Higher consumption
Blocked pump and mixing valves

Where do hydrogen and black sludge come from?

The process starts when the installation is filled with water and is accelerated by heat production. Water breaks down and the dissolved oxygen corrodes metals, creating hydrogen and black sludge.

This corrosion becomes faster when different metals are present and when the temperature is high, which is common in a heating installation. These factors are compounded by the presence of sulfates, chlorides and other impurities in the water.

What should you do in that case?

It is necessary to treat the water.

If you notice cold zones in your underfloor heating or your radiators, noises in your boiler, or if the water is red or black when you drain your radiators, then it is probably time to de-sludge your heating circuit.

De-sludging is essential because deposits thicken over the years and affect the performance of the heating system, and therefore the user’s comfort.

Do not hesitate to contact a professional for a diagnosis.

We recommend that you use specific chemical products for de-sludging. Warning: some of these products are aggressive and can accelerate the ageing of the heating system.

When the de-sludging is complete, you must inject a scale and corrosion inhibitor as a precautionary measure. It is also recommended to use a corrosion inhibitor for new equipment.

If you have underfloor heating, it is recommended that you de-sludge your equipment every 10 years. The same goes for heating circuits.

Such an operation may seem expensive, yet if a heating circuit is well maintained, the boiler will work for a shorter period during the day and last longer. You may therefore save between 10% and 25% of energy.

Recommended treatment

New installation

TREATMENT In steel, copper, iron and plastic With aluminium
SLUDGE REMOVER - -
PROTECTION Code: 904840
HEATING FLOOR PROTECTION
Anti algae, corrosion, tartar, bactericidal		 Code: 904840 Code: 904840
ANTI NOISE Code: 904842 Code: 904842

Old installation

TREATMENT In steel, copper, iron and plastic With aluminium
SLUDGE REMOVER
PROTECTION Code: 904840
HEATING FLOOR PROTECTION
Anti algae, corrosion, tartar, bactericidal		 Code: 904840 Code: 904840
ANTI NOISE Code: 904842 Code: 904842

If you de-sludge by yourself, you need to equip yourself with professional gloves, protective glasses 906272, and a protective suit 904641.

For tools, you will need a multifunctional tool, and more precisely a Knipex® purge key 901587. Knipex® tools are of professional quality.

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