Corrosion Report

Harvey Water Softeners Corrosion Report

The effects of water softening on the corrosiveness of water are widely misunderstood. There is much confusion and misinformation over the issue. This is especially true with regard to the suitability of water softeners for homes that have boilers with aluminum heat exchangers.

December 2010

The myth that softened water should not be used with aluminum heat exchangers found its way into the British Standards in 1992 via BS 7593:1992. After several years of trying to resolve the situation, all the British Standards and Building Regulations Guidance documents have finally been updated.

However, even though our research shows it is not necessary, in order to get Energy Saving Trust approval for our water softeners, there must be a BuildCert approved corrosion inhibitor for use with softened water.

We are currently waiting for the technical committee of the boiler manufacturers of the HHIC to formally request this from BuildCert.

November 2011

The National Physical Laboratory publishes guides to good practice and they have recently revised their Guide No. 120 “Avoidance of Corrosion in Plumbing Systems”. It gives a good overview of corrosion problems in plumbing systems.

What is notable, from our point of view, is that there is no mention of softened water causing any corrosion issues except in the very rare occurrences where it enhances erosion corrosion in hotel hot water loop systems.

So by omission, softened water does not cause corrosion.

Further reading:

• HHIC presentation Dec 2010 A presentation by Harvey Bowden to the Heating and Hotwater industry Council.

• Corrosion Report Dec 2010 A chronological report of events with references.

• Glossary A glossary of terms and abbreviations. Open and print off before you start for reference.

• Corrosion Simplified An explanation of the corrosion processes involved.

• Munn Fernox 1993 The testing of Corrosion Inhibitors for Central Heating Systems.

• German VDI 2035 Part 1 Prevention of damage in water heating installations.

• German VDI 2035 Part 2 Water-side corrosion.

• German BS EN 14868 Protection of metallic materials against corrosion.

• Viessman Technical guide for central heating systems.

• National Physical Laboratory Avoidance of Corrosion Problems in Plumbing Systems (updated in 2011 to remove references to softened water).