Andrews' SOLARflo water heating system installed in award-winning City of London refurbishment


Andrews Water Heaters, part of Baxi Commercial Division, supplied the SOLARflo water heating system and MAXXflo gas-fired storage water heater installed at 23-25 Great Sutton Street, which won five awards, including the Sustainable Buildings Award for architects John Thompson & Partners at the City of London Corporation's Sustainable City Awards.

The award recognized the exemplary upgrading of an existing 1920s warehouse to incorporate systems, technologies and materials that substantially reduce energy demand and emissions, provide sustainable energy supply and minimise both water usage and waste. More recently, the building has also won CoreNet's 2010 Global UK Chapter Award for Sustainability and Innovation.

OR Consulting were the Building Services designers behind the installation. The Andrews SOLARflo system which supplies the building's domestic hot water comprises solar collectors linked to a stainless steel cylinder which pre-heats the building's domestic hot water and in turn supplies a high efficiency condensing storage water heater.

In an innovative concept, four arrays of evacuated tube solar collectors mounted over windows on the second and third floors of the building's south-facing elevation fulfill a dual function, serving both as heat generators and as brises soleils to minimise solar gain. The hot water serves wash hand basins and showers throughout the building. Additional showers were installed during the refurbishment in order to encourage sustainable transport and this provision, together with lockers, towels and secure cycle storage resulted in an increase from 8% to 25% of staff cycling to work. It is believed that this made a substantial contribution to an annual reduction in the number of days lost through sickness from 461 to 181.

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 and, operating at lower ambient temperatures, they are capable of providing a higher annual percentage of domestic hot water.

A further advantage of evacuated tubes is their ability to be rotated in order to maximise solar irradiation. 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.

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. Water preheated by the solar collectors is transferred to a stainless steel unvented cylinder which in turn supplies the Andrews MAXXflo water heater, considerably reducing consumption of natural gas.

The Andrews' MAXXflo s Award for Innovation for their impressive energy saving capabilities.

MAXXflo Legionella program is incorporated for maximum protection. The MAXXflo range of condensing storage water heaters consists of nine models with tank capacities of 200 or 300 litres, a choice of four nominal outputs from 30kW to 120kW and recovery rates up to 1920 litres/hour through a temperature rise of 50oc.

The water heaters' small footprint ensures ease of siting in plantrooms with restricted space and multiple flue options, including standard and roomsealed, allow greater flexibility in locating the unit. MAXXflo condensing storage water heaters are designed to operate on natural gas or LPG.