The project

Telephone House is a large office complex located in central London close to the Embankment. The building, which dates from around 1900, is listed due to its special architectural interest.

Guardian Water Treatment was asked to investigate the building’s LTHW system in 2017 due to a number of issues that had arisen.

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Hidden problems

Historically, the radiators throughout the building had been leaking on a regular basis – every week in fact. Although the BSRIA Chemistry and bacterial results were in guideline limits and iron levels and solids were also in spec, this leakage suggested another cause of corrosion, one not picked up by the usual sampling methods.

Midland Corrosion’s detailed analysis cited Gross Aeration as the problem when they discovered oxide deposits in the radiators’ water channels. At some point, oxygen had got into the sealed system. How or when this had happened wasn’t clear; the system could have been partially drained down for an extended period during commissioning.

Whatever the cause, the pressing issue was to get on top of the problem before it started to do real harm to the system, which could potentially lead to costly repairs and operational downtime. Flushing – which is many engineers’ standard reaction to closed water system issues – in this instance would not have been effective.

Real-time monitoring

Guardian installed Hevasure’s real-time monitoring solution, Hevasure, in May 2017, to provide a three-month health check on the system.

Owing to the success of this initial trial, the period was extended to January 2018, by which time all aeration issues were sorted and the system had stabilised.

The results taken from graphs created over the period indicated that insufficient water pressure on the 4th floor was the problem.

During every “standby” period, when the water was cooler, the pressure dropped and the oxygen levels spiked. Conversely, when the system was hot and the pressure stable (3.3bar basement, 0.7bar 4th floor) the DO levels were seen to reduce and stabilise.

 

> Hevasure real-time monitoring

Hevasure findings

The Hevasure unit was installed by Guardian on Friday 12th May. Sited in the basement near the LTHW pump set, the system was online and sending real-time data within just a few hours of installation.

The system monitored a range of parameters in order to get a real-time view of system integrity, water characteristics and corrosion:

  • Dissolved oxygen
  • Pressure
  • pH
  • Conductivity
  • Galvanic currents (related to corrosion rate of steel surfaces)
  • Crevice corrosion
  • Leaks (water makeup)
  • Temperature
  • Inhibitor/glycol concentration

Conclusion

By installing Hevasure’s system, Guardian was able to provide its clients with not only a live diagnostic too, but real peace of mind. By nipping the pressure issue in the bud, straight-forward adjustments to the system prevented the spread of serious corrosion problems which would have lain undetected by sampling.

If the oxidation in the LTHW had continued, there would have been an eventual breakdown of the whole system, leading to major repair expenses and disruption to the organisations housed in the building. By fixing the root cause of the problem, unnecessary chemical usage, maintenance costs and the building’s environmental impact, have been reduced.

When conditions are continually monitored issues are flagged up before they get out of hand, allowing inexpensive repairs to be carried out by in-house maintenance teams. With the Hevasure system, water system condition is no longer a mysterious art; the preserve of costly consultants, it is something FMs, building managers and owners can view and act upon themselves. Guardian believes Hevasure has the potential to turn LTHW and CHW system care and maintenance on its head and prevent corrosion for good.

Following this analysis, Guardian was able to recommend that the client investigate the matter further leading to the identification of air ingress that pointed to fixes to the expansion vessels, pressurisation units and AAVs. The system resting pressure and operating parameters were also reviewed. Once the pressure had stabilised and the DO levels were kept in check, corrosion rates became negligible and the inhibitors worked effectively.

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