For all those who take responsibility for systems

Modern heating systems provide more efficiency, more control technology, more comfort – but they have also become more sensitive. If you simply fill them with tap water without checking it, you risk limescale damage, corrosion, magnetite sludge – and the failure of entire components in the long term.

The days of simply topping up with “any water” are over. Today:
Safe and standard-compliant operation is not possible without targeted heating water treatment.

What happens without water treatment?

If you do without preparation, you open the door to problems for the technology in several places:

Limescale formation due to high water hardness

If hard water is filled in untreated, limescale deposits form when it heats up – preferably on heat exchangers, control valves and pipes.
Result: efficiency drops, condensing boilers run inefficiently, pumps have to work harder.

Corrosion due to oxygen ingress

Rust forms in combination with ferrous materials. Even small amounts of dissolved oxygen are enough to cause material erosion and brown sludge in the heating circuit.
Consequences: magnetite sludge, clogged valves, blocked pumps.

Incorrect pH value = material attack

If the pH value is too low, aluminum decomposes. If it is too high, the water attacks galvanized components.
The pH window quickly becomes critical, especially in mixed installations. A value between 8.2 and 9 is ideal.

High conductivity = electrochemical risk

Dissolved salts act as a “bridge” between different metals in the system – electrical potential differences and corrosion occur.
Classic example: Pitting corrosion on the aluminum heat exchanger despite apparently clean water.

VDI 2035 is not an option, but the standard

The VDI Guideline 2035 formulates clear specifications for the quality of filling and make-up water:

Total hardness: if possible <0.3 °dH
Conductivity: ≤ 100 µS/cm for mixed installations
pH value: 8.2-10 depending on material, for aluminum 8.2 – 9
Oxygen: <0.1 mg/l (closed system)

If you do not comply with these values, you risk losing your warranty – because most manufacturers base their conditions on these guidelines.

Why the topic is often underestimated

In practice, heating water is often treated as a “filling agent” – although it is the most important system component of all.
After all, what good is the best system technology if the water in it promotes corrosion?

Typical problem areas:

No water quality check during initial filling
Replenishment via the normal domestic water connection
No documentation of the parameters
No regular follow-up checks during maintenance

In the event of damage, the heating engineer is responsible.

What you can do as a specialist company

Professional heating water treatment is not rocket science – it can be implemented efficiently and legally compliant with the right tools:

Measuring instead of estimating

Use a digital measuring device, e.g. our WaterBoy, to check the conductivity and pH value precisely.

WaterBoy measuring case

The UWS WaterBoy measuring case contains everything the HVAC specialist needs to measure data in accordance with the VDI 2035, ÖNORM H 5195-1 and SWKI BT 102-01 standards in two L-BOXXES.
To the product

Desalting instead of just softening

Use full demineralization with mixed bed resin (e.g. Vadion pH-Control) to remove all ions and achieve standard water values.

Mixed bed resin Vadion pH-Control

Our Vadion pH-Control is a mixed bed resin that not only desalinates the water to < 100 μS/cm (equivalent to 0-2 °fh) but also ensures that the pH value of the filling water is within the required range.
To the product

Secure the backfeed

Use permanently installed make-up units with system separators in accordance with EN 1717 (e.g. our Heaty Complete Advanced / PROfessional) in order to have make-up water permanently under control.

Heaty Complete PROfessional

The Heaty Complete PROfessional is the world’s first smart IoT top-up system incl. Cloud connection – fully automatic, leakage protection and digital water meter.
To the product

Document and check

Keep a system log at the customer’s premises with all measured values – this protects you in the event of a warranty claim and creates trust.

Conclusion: Heating water determines function and service life

Heating water is not a side issue – it is an active operating resource.
If you ignore it, you risk a loss of efficiency, corrosion and breakdowns. Those who treat it ensure safe, long-lasting and low-maintenance operation.

Featured photo: Adina Voicu (Pixabay)

Why heating water treatment is not a “can”, but a “must”