Modern Building Services

18 MODERN BUILDING SERVICES JANUARY 2022 FEATURE PIPED SERVICES T he Association of German Engineers (Verein Deutscher Ingenieure) or VDI, are the 150 000 member German equivalent of CIBSE. VDI2035 part 1 & 2, which have now been combined, is the VDI’s document for “Prevention of Damage inWater Heating Installations”. This document explains how corrosion can be prevented in closed loop systems without the use of chemical inhibitors or biocides. Whilst it’s not being heavily policed in the UK many of the major HVAC manufacturer’s manuals mention VDI2035 and its inclusion in EN12828 is the most significant change to the EU standard. For a deeper delve we talk with some of the proponents of electro chemistry and discuss the challenges and strengths that it brings to the UK market. David was an early adopter prior to opening their UK branch office. As the founding director of Geminox UK, a specialist provider of communal and district heating solutions, David had been using the system since 2004 to protect new aluminium boilers and to clean through existing corrosion and bacteria issues on adopted networks. He recognises the “leap of faith” and readily admits that after sleepless nights following the first install, he added chemicals back to the system only to witness them being successfully stripping them out. So, what changed his mind? “Once we applied it to other networks where there had been major issues you could see the physical improvements with your own eyes. Complaints drop off and the test results show all levels improving. At this point even the most hardened sceptics are won over and we have never failed to clean through a system yet”. As the innovators in electro chemical water treatment, they now have over 60 000 global installs. Recent clients in the UK include Stoke onTrent City Council’s newest district heating network, CBRE, Savills, Broadgate Estates andmost recently a datacentre for amajor high street bank, so the good and great are starting to use the approach. How does it work? So how does electro chemistry work and what are the principles of VDI2035. VDI2035 recognises the contributing elements to corrosion in closed loop hydronic systems and states that controlling these to strict levels creates an environment hostile to both corrosion and bacteria. The table below shows these elements and levels necessary to achieve the criteria set out in VDI2035 and compares it to the guidelines recommended by BSRIA in BG29. Element VDI2035 Levels BSRIA BG29 Levels Hydrogen ph 8.2 - 10 * Chloride mg/l (cl) 10 * Copper mg/l (cu) 0.02 Less than 1 or * Iron mg/l (fe) 0.1 Less than 3 Dissolved Oxygen 0.1 Less than 2 Total hardness mg/l 10 - 200 * Conductivity uS/cm 50 - 100 * Eschewing chemical additives in closed loop water treatment for a more environmentally friendly and cost-effective alternative has long been accepted on the continent. Now, with the recognition of VDI2035 in CIBSE’s revised Code of Practice on Heat Networks (CP1 (2020)), it would seem the UK is finally catching up says DavidWhitfield , MD of Elysator UK. The Long Goodbye to Chemical Water Treatment in Closed Loop Networks PIPED SERVICES, PUMPS &WATER