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Chemical-free water treatment

IWTM’s chemical-free water treatment was selected for the 8 storey 80,000 sqft office block following issues faced from the chemical flushing on its next-door sister office and completed the turnaround in a 90 day proof of concept. Built in 2005, the series of 3 Grade A office blocks on Wigmore Street had all been suffering from poor water quality. Multiple dead legs from unsupervised fitouts and a regime split between fixed and flushing strategies were seen as significant contributary factors. The poor water quality had resulted in multiple component failures, leaks, blocked valves and full strainers which led to a large volume of occupier “hot and cold” complaints.

Proof of concept

Whilst a chemical flush had been completed on one of the blocks with some initial success, access issues meant hatches had to be cut into ceilings and the general age of the system saw issues with seized valves, blocked fan coils and leaking pipes. Keen to not repeat the previous experience just to see the water quality issues return an introduction was made to IWTM and a site survey was completed within the week. Initial discussions on chemical-free water treatment were met with skepticism from the onsite engineers but results from previous installs and the expertise and knowledge of the IWTM team led to the acceptance of a proof of concept for a single circuit. A solution of an Elysator 50 and a Purotap Compenso 25 was selected for the LTHW network with a view to being introduced across the rest of the networks on the 3 buildings. The installation was completed on the 9th December 21 and a rinse was performed on the 8th February 2022 with final testing on the 31st March to complete the proof of concept. In just over a week from install the Resus Corrosion Meter showed the system water had moved the corrosion from 140 µm/yr to below 20 µm/yr which is indicative of the Elysator units efficiently removing dissolved oxygen (DO) from the system. pH was maintained between 8.7 and 9.2 for the POC period which is in line with VDI2035 water quality requirements. Conductivity of the system decreased from 614 uS/cm at the time of installation to 60 uS/cm immediately post rinse.


Good improvements were seen in the total and dissolved metal values in the system water compared to the quality preinstall. The dissolved metal values which usually represent active corrosion are already in VDI recommended ranges. Initial Iron values were above 1 mg/l indicating corrosion debris present in the system and along with other metal values continues a downward trend whilst both hardness and chlorides are both at VDI2035 levels. Commenting after the successful proof of concept the site supervisor stated “Whilst initially sceptical as it really seemed to good to be true I now think the system is brilliant. We were regularly testing the water and you can just see all the levels falling as the Elysator unit brings them under control and the results just don’t lie”.

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