Protect the system with the water itself.Not with a drum of inhibitor.
VDI 2035 prevents scale and corrosion in heating and cooling systems by controlling the water chemistry: low conductivity, controlled pH and low oxygen. We design, fill, polish and maintain systems to it, and we are the exclusive UK distributor of Elysator.
- VDI 2035 Parts 1 and 2
- Exclusive UK Elysator distributor
- Mobile demineralisation
Two ways to protect a closed system.
| Inhibitor treated | VDI 2035 salt poor | |
|---|---|---|
| How corrosion is controlled | Chemical inhibitor kept within a dose range | Water chemistry: low conductivity, controlled pH, low oxygen |
| Typical conductivity | Often above 1,000 µS/cm | Below 100 µS/cm |
| Ongoing chemical cost | Top ups after every loss of water | None |
| What fails it | Under dosing, dilution, microbiological breakdown | Uncontrolled make up and air ingress |
| What we verify | Inhibitor level, bacteria, corrosion indicators | Conductivity, pH and oxygen at fill and over life |
VDI 2035 from design to day to day operation.
Design review
Materials, make up and degassing checked so they suit a salt poor regime.
Initial fill and polishing
Mobile demineralisation to a recorded conductivity and pH endpoint.
Conversion
Existing inhibitor treated systems converted to VDI 2035.
Elysator
Units for continuous side stream treatment and degassing, from the exclusive UK distributor.
Make up water treatment
So the system stays salt poor for life.
Monitoring
By sensor or by sample, interpreted against the regime.
Sometimes the best evidence is captured at fill.
On small loops with manual top up, every sample drawn is replaced with mains water that adds oxygen and salts. In those cases we capture the evidence at fill instead, and leave the chemistry alone.
Is VDI 2035 recognised in the UK?
VDI 2035 is a German guideline, referenced in EN 12828 for the design of water based heating systems. Many boiler and heat pump manufacturers base their fill water requirements on it, and it is increasingly written into UK specifications.
Can an existing treated system be converted?
Usually, yes. The system is cleaned, the inhibitor removed and the water demineralised in side stream until it reaches the target conductivity and pH, then make up is controlled so it stays there.
Does VDI 2035 work with aluminium heat exchangers?
Yes, but a tighter pH window applies where aluminium is present, because aluminium is attacked at high pH. That has to be designed in from the start.
Do we still need to sample the system?
Sometimes. On large systems, monitoring conductivity, pH and oxygen confirms the regime is holding. On small loops with manual top up, sampling can do more harm than good, so the evidence is captured at fill instead.
Considering VDI 2035 on your next project?
Talk to us at design stage.