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Central Saint Giles takes control with Keraflo’s Tanktronic

One of London’s most vibrant mixed-used developments has retrofitted Keraflo’s advanced electronic tank management system, Tanktronic, to help it take more precise control of its cold water storage and usage.

Central Saint Giles in the West End was completed in May 2010 and is home to some of the world’s leading media companies.

The prestigious destination consists of two buildings up to 15-storeys high that include 408,000 sq ft of office space, 109 residential apartments, restaurants, cafes, ‘green’ roof terraces and a public piazza.

Its substantial water use and cooling needs are managed through four huge tanks, each holding between 65,000 and 75,000 litres.
While the development has achieved some outstanding sustainability awards, its water system was prone to occasional flooding in the basement where the storage tanks are held.

Retrofitting Keraflo’s Tanktronic has not only resolved the flooding issue, it is also enabling M & E services provider ABM Technical Solutions to maximise the system’s operational effectiveness while furthering the sustainability goals of property owner Legal & General Investment Management.

Luke Hedges, Technical Services Manager for ABM at Central Saint Giles, said: “The beauty of Tanktronic is it can tell the system when to turn the supply on and off. It has allowed us to install automatic valves instead of mechanical ones, which was the reason for the flooding.

“Problems would occur overnight and at weekends with too much water entering the Recycling tank, our most critical tank, which has a primary direct feed from the Cooling Towers discharge.

“The old system did not provide a signal; it was in effect an ‘old school’ float that would get caught on the tank’s bracers.”

Tanktronic comprises a simple-to-set-up Control Unit, which can control and monitor water and temperature levels in up to four individual tanks, a connection box and a sensor assembly that is suspended at full depth inside the storage tank.

Able to send alarms to a Building Management System, each Tanktronic Control Unit can manage up to four individual tank sensors, eight motorised Tanktronic Servo Ceramic Valves and two electro-mechanical Tanktronic Control Valves, plus additional third-party devices. An expansion S-Module enables further Control Valves to be added, if required. A Battery Module can also be specified to provide back-up power to the electrical mains supply.

Each tank can be set with its own operating levels to follow up to 10 schedules, including valve close level, fill delay, alarm high / low and temperature high / low.

Intelligent features include a “holiday mode” schedule to match fluctuating demand and a two-stage alert for high and low water levels and temperature, with a second stage override that takes evasive action if the first-stage alert is not responded to.

Luke said that with the help of Tanktronic the centre is able to achieve a more efficient balance between taking potable water from the mains for domestic purposes, while maximising the harvesting of rainwater and recycling of grey water for flushing toilets and irrigation, even washing down the car park.

He said: “At times we were finding our overall water usage was very high because we weren’t managing the recycled water as efficiently as we can now. We were drawing extra potable water to top up the recycling tank, basically to flush toilets. The levels of the two were out of kilter.

“In looking at Tanktronic, we wanted to be able to reduce the volumes taken from the town’s main and maximise the use of recycled cooling water. The system is more efficient.”

Another consideration is that the amount of taken water from the mains is reflected in the service charge. So, the better it is managed the better it is for occupiers.

Sustainability continues to be a key driver at Central Saint Giles, where 60% of rainwater falling on offices roofs and in the piazza is collected, treated and recycled, while 100% of water discharged from its cooling tower is collected for re-use.

Jeff Lengthorn, Property / Engineering Manager at Central Saint Giles, said because of the more effective control they are able to maintain the water at a lower level in the tanks, which could not be achieved under the float system.

There was also a payback on the investment in less than three years.

He concluded: “Tanktronic helps us achieve two prime objectives; 1) the system is more efficient, and 2) it makes a key contribution to our sustainability goals. We are more much eco-friendly.”