Key factors in the specification of UltraGas boilers were their high energy efficiency and their compact design, enabling optimum use of plant room space.

Opened by HRH Prince Philip Duke of Edinburgh in October 2006, the Emirates Stadium covers an area of 17 acres and has a capacity for 60,000 spectators. The project has created 2600 new jobs in the area and also includes construction of 2500 new homes in the Borough of Islington. The stadium was designed by HOK Sport and the main contractor was Sir Robert McAlpine Ltd. Building services were designed by Buro Happold and mechanical services installed by MJN Colston.

“The boilers are located in eight rooftop plant rooms and are energised 24 hours a day, using a primary loop that is always charged with hot water at the flow temperature of 80°C,” explained Buro Happold’s Peter Naylor. “Each boiler set uses a common header combined with constant volume and variable temperature pumps and another set of constant volume pumps serving a plate heat exchanger.”

“This arrangement, combined with the zoned control, provides a very responsive and efficient system. To optimise condensing, the return water temperature is set to 50°C,” he added.

Hoval also supplied condensate collection reservoirs for each boiler, with built-in condensate pumps to discharge condensate to the drains.

Effective control of the boilers is vital to ensuring a fast and efficient response. “The first level of control is through the Hoval controllers on the boilers, which are interfaced to a building management system,” explained MJN’s Simon Stothard.

UltraGas pre-mix condensing gas boilers are designed to couple high efficiency with low emissions, thus minimising environmental impact. When tested to the requirements of the European Boiler Efficiency Directive, UltraGas boilers achieve net efficiencies of up to 109.5%, NOx levels of less than 40 mg/kWh and CO levels of 16 mg/kWh.

Plant room space was another important consideration and necessitated extensive 3D modelling by Buro Happold. The compact design of the UltraGas boilers proved invaluable in ensuring that plant room space was optimised while ensuring adequate space for maintenance.

For ease of maintenance, UltraGas boilers have very few moving parts and are designed to allow easy access to all components. Features such as a fold-down platform for access and the use of gas-powered hinges for raising the burners all help to keep downtime to a minimum and to cut maintenance costs. Unlike most boilers, the purchase price of UltraGas boilers includes the cost of parts that will require occasional replacement, such as the boiler electrodes.

Maintenance of the boilers will be carried out by Hoval’s dedicated maintenance team, which is accredited under the Safe Contractor Scheme.