ANDREWS’ RENEWABLE, ENERGY EFFICIENT WATER HEATING FOR UNIVERSITY OF PLYMOUTH’S NEW NANCY ASTOR BUILDING

Andrews Water Heaters, part of Baxi Commercial Division, has supplied two Queen’s Award winning MAXXflo direct fired storage water heaters, together with a SOLARflo pre-heat system which have been installed at the new Nancy Astor Building, an £11 million development at the University of Plymouth. This building, named after the Plymouth Sutton MP who was the first woman to serve in the House of Commons, is at the centre of a major scheme connecting the campus with the Drake Reservoir and its adjoining parkland. The Nancy Astor Building is the new home of the Faculty of Health and Social Work.

Designers Hoare Lea selected the Andrews equipment for its use of renewable energy which complements an already highly efficient water heating system in order to comply with a number of important criteria: the University’s policy on carbon emissions, Part L of the Building Regulations, the requirement for a ‘very good’ BREAAM rating and, last but not least, the company’s own policy of minimising the carbon footprint of its design projects.

A spokesman for Hoare Lea commented, "A real benefit was that Andrews were able to supply the whole package, which made the design much more straightforward than combining water heaters and solar system from separate manufacturers.”

The Andrews Water Heaters package is designed to provide abundant, virtually instantaneous, domestic hot water to the entire building. Outlets in the Nancy Astor Building comprise 17 showers, 28 wash hand basins and 10 sinks located within the sports facility, the academic teaching area, the café area and including all WC, cleaners and tea point facilities to the 4 storey office accommodation. The two MAXXflo CWH120/300 storage water heaters are located in the Energy Centre on the lower ground floor, along with a 1500 litre stainless steel pre-heat unvented cylinder and the other components of the solar heating package. The 21m2 of SOLARflo evacuated tubes for solar collection are mounted horizontally on the flat roof of the North Core plant room, some 28 metres above the Energy Centre. The University of Plymouth’s framework building services contractor and installer of the equipment, MITIE Engineering commented, "Installation of all the Andrews equipment went well and the evacuated tubes were very simple to install. With outlets located throughout the building, programming required careful planning and co-ordination and the support and back up received from Andrews was excellent.”

Water is preheated by the solar collectors, which have the evacuated tubes rotated to an angle of 20 degrees in order to optimise their efficiency.

The heat is then transferred to the single coil unvented cylinder which in turn supplies the two MAXXflo water heaters, thereby considerably reducing consumption of natural gas. In addition to the solar collectors and cylinder, the complete SOLARflo package includes solar controls, pump station, expansion vessels, first fill of heat transfer fluid and collector mounting accessories.

The MAXXflo range of gas-fired storage water heaters consists of nine models and a choice of four nominal outputs from 30kW to 120kW, all achieving an operational efficiency of 109%. Winners of the Queen’s Award for Innovation for their energy saving capabilities, these units are ideal for buildings with a high demand for hot water and particularly suitable for installations such as sports facilities, where this demand peaks at particular times of the day. Thanks to their fast recovery rate and innovative design, carbon footprint, NOx levels and running costs are kept to a minimum. The Andrews MAXXflo CWH120/300 models selected for this project have the largest capacities in the range at 300 litres, and feature robust stainless steel construction which ensures a long service life. Each has an output of 30 to 120kW and a recovery rate of 2040 litres through a temperature rise of 50oC. The water heaters are controlled by a digital, electronic master controller which is provided with BMS and other external interfaces. In the Nancy Astor Building, the water heating system is controlled via the site Building Energy Management System.

Available in 20 or 30 tube options, SOLARflo evacuated tube collectors are ideal for larger commercial water heating applications as they have a higher annual, average thermal efficiency than glazed flat plate collectors (83% against 78%) and, operating at lower ambient temperatures, they are capable of providing a higher annual percentage of domestic hot water. In addition, they require less surface area of collector array per litre of stored water. Other advantages of evacuated tubes include their ability to be positioned horizontally or vertically, with tubes rotated by +/- 25o in order to maximise solar irradiation. SOLARflo evacuated tubes are Solar Key Mark Approved and, in common with the glazed flat plate collectors and stainless steel unvented cylinders in the range, carry a 10 year guarantee.

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