With water companies continuing to reduce the mains pressure to help hit leakage targets, the requirement particularly from local authorities and housing associations for pressure boosting equipment to ensure there’s water coming out of the taps on the top floors of tower blocks continues to grow. Unboosted water struggles to get above the third floor in most parts of the country.
A company that has specialised in the provision of these systems is Letchworth-based Complete Building Services Herts (CBS). Director Peter Bradbury says that several of their clients have been looking to install pressure boosting equipment and the key to the success of these projects – apart from reliable pressure boosting sets – is easy installation and as little disruption to the lives of tenants as possible during the installation process. They’ve hit on a solution to all these requirements through their partnership with leading pump manufacturer Wilo.
This is perfectly illustrated by recent work undertaken by the company for clients Enfield Homes, the social housing arms-length management organisation (ALMO) for Enfield Council. Four tower blocks in Enfield, just inside the M25 in north London needed pressure boosting equipment to get the mains water reliably up to the top of the 13 story buildings.
The existing equipment – based in the basement of Brittany House was not up to the job and its reliability had begun to be called into question. CBS was asked to provide a solution that would provide reliability, cost effectiveness and the minimum of disruption to the tenants in the nearly 400 apartments affected. CBS is well placed to deliver the complete package of support with its excavation, building and heating and plumbing expertise.
Enter Wilo UK with its comprehensive range of pressure boosting sets. They recommended their Wilo Comfort-Vario COR-2 Helix 1603/K/VR speed controlled pressure booster set, supplied with a CAVSA anti surge valve to address the potential issue of hydraulic shock in the mains water system. Controlling the flow of water into the system can prove difficult, as you don’t want to affect the flow rate under normal working conditions.
Preventing a vacuum can be achieved by fitting CAVSA valves (combined air vent & surge arrestor) at the top of each riser which will act as a vacuum break by allowing air to enter the system. These valves will also control the release of the air from the system when it starts to refill, therefore slowing down the rate at which the water enters the system.
The pump set selected for this project combines three pumps and the three-pump approach sees one operating, one able to assist if the call on water exceeds the capacity of that first pump, whilst a third remains on ‘standby’. All three pumps operate on a cycle, ensuring even wear across each of the pumps, with the added benefit that there is no stagnation of water addressing any legionella bacteria issues in the system.
Pete Bradbury says CBS received plaudits from the client Enfield Homes for the speed of the job they undertook: “They were really impressed by the downtime that was achieved on this job. The water was off to the nearly 400 dwellings for less than two hours whilst the old system was decommissioned and removed and the new one installed and powered up. They had no complaints from tenants at all having warned them the work was being done and that they would have to survive without mains water for a short while. It’s human nature to scoff when you get messages like that through your door and you prepare for the worst – possibly no water for a day! But we were as good as our word and had the water back on in less than 120 minutes from the time it went off!”
Kevin Alexander, senior mechanical engineer at Enfield Homes was impressed by every aspect of the project: “As the water pressures are reduced we have serious issues with the potable water supply in our high rise developments across the borough. With this particular project we seem to have hit upon a very straightforward, easy to install and effective solution to the problem for the nearly 400 tenants who live in the high rise blocks affected. The solution was suggested to us by Complete Building Services, using a Wilo pressure boosting pump set that does the job perfectly and the design of the unit offers the in-built reliability and back-up that is essential for us and our tenants. In an area of our work where tenants quite reasonably assume they will get reliable water supplies from the mains but do not see what is behind that reliable supply, it is a job well done. And the cessation of supply to our tenants to fit the new system was remarkably short – less than two hours. That was quite remarkable and very welcome.”
The Wilo pressure boosting system option selected by CBS delivers in all areas. Powerful motors allow a powerful drive and reliable pressure boosting. The highly efficient automatic functions offer a wide range of flexible parameters to be utilised to optimise the pressure control according to the specific characteristics of the building's water network. Moreover, the system hydraulics were designed to meet the highest demands in terms of long service life and effectiveness. Beyond the optimised 2D/3D laser-welded pump stages, flanged pipes minimise pressure losses while the stainless steel, high quality hydraulic parts ensure a high resistance to corrosion. The installation-friendly systems are easy to operate. The display with in-built backlight, shows all relevant information at any time and the transparent menu structure allows quick access to the main parameters.
Due to the clever technology incorpated in the system, set-up is rapid thanks to the standard interface on the control cabinet and the pumps. The combination of an LC display and "red-button technology" from Wilo, enables straightforward settings and status information and the Wilo systems are ready for use very quickly. In order to optimise security, the pressure gauge and the pressure transmitter sensors are protected with extra covers. In addition, a cable channel ensures improved integration of the cables. Communication between the pressure boosting pumps and building management systems if installed, is possible via different data buses, including LON, ModBus and BACnet.
The Wilo Comfort system has two to four stainless steel high-pressure centrifugal pumps – in this case three - of the Helix VE range. The pumps of this highly efficient and connection-ready water-supply unit are switched in parallel and vertically arranged - including an air-cooled, integrated frequency converter. The integrated dry-running protection makes sure that in the event of low water, the motor control electronics will be automatically switched off. Thanks to the Smart Controller SCe control device, operating this system is particularly straightforward.
A subsequent project for the same client on a tower block in nearby Edmonton saw the water off for just an hour whilst the new Wilo pressure boosting set was installed.