Hybrid chiller in “excellent” project

UK: A new type of hybrid heat pump chiller is supplying high efficiency cooling and heating for a state-of-the-art refurbishment project at Northbrook College’s West Durington Campus.

The £6.6m project, carried out by main contractor Morgan Sindall, is designed to transform the college’s West Durrington campus, with the addition of a new three-storey learning centre and entrance area with exhibition space, high-tech library, seminar rooms and a refectory. The staged project also includes a new drama block.

The Rhoss EXP TXAETY 4200 heat pump chiller, supplied by Klima-Therm and installed by Maybourne & Russell, was chosen for its ability to deliver low energy simultaneous chilled and hot water for use in air conditioning, heating and domestic hot water supplies.

The project achieved a BREEAM rating of Excellent. Windows, floors, roof and walls of the new building are highly insulated to minimise energy loss in the winter and reject heat gain in the summer. The roof contains photovoltaic panels to convert sunlight into electricity.

M&E consultant HamsonJPA chose the Rhoss EXP heat pump chiller because of the significant potential energy savings that could be delivered. Analysis of load profiles for the new building suggested it offered an ideal solution, as much of the year there will be a simultaneous requirement for heating and cooling.

It is said to combine three core technologies: a high efficiency heat pump based chiller, an energy and heat recovery system, and an advanced control system that regulates and optimises the functioning of the combined system across a building to deliver the lowest possible energy usage while delivering set conditions.

Onboard intelligent controls on the Rhoss EXP machine ensure it delivers the precise amount of heating and cooling required to meet current building demand, all without BMS intervention. Temperature sensors across the evaporator and hot water production heat exchanger enable the chiller to sense if a load is required.

When there is demand for cooling only or heating only, the air-cooled condenser section of the chiller is used to reject or absorb heat as required, ensuring optimum efficiency in all operating modes.

The system design, with contributions by MLM in Ashford, Kent, incorporated a hot water buffer vessel, also acting as a low header between the chiller’s primary circuit and the building secondary circuit. The configuration is designed to eliminate the possibility of compressor short cycling. This approach was also taken on the chilled water side.

Unusually, the Rhoss EXP chiller has individual heat exchangers for chilled and hot water production, which connect separately to their relevant pipework circuits. This is sad to improve efficiency and performance, while simplifying installation and system control.

Among the first units of its kind to be installed in the UK, the system at Northbrook College is equipped with integral pumps, making it even simpler to install.

Andrew Latus, who headed the project for Klima-Therm said: “The building design and diverse use lends itself perfectly to EXP technology, as it delivers its highest efficiency when operating in simultaneous heating and chilled water mode. As this is the default condition for the building for the majority of the time, the system delivers exceptional efficiency and significantly lower running costs than competing systems.”