Consulting engineers Pick Everard evaluated several replacement options. Jeff Fleming, head of the project for Pick Everard, explains, ‘A key issue at the site was that there was no headroom on the electricity supply. Cooling loads had grown since the original chillers were installed, and replacing with a larger conventional electric chiller would have required a big investment in additional power supply.

‘The Sanyo gas-engine-driven heat pumps, which use R410A, not only provided a way round the power problem, they are also a highly energy-efficient solution. Our studies showed that in terms of life-time costs, energy consumption and carbon emissions, they come out well ahead of comparable electric systems.’

The units, which are very quiet, each have a cooling capacity of 56 kW. The heating they provide in winter replaces inefficient steam heater batteries.

Each unit produces 18 kW while it is cooling, which can be used for the DHW supply. Separate refrigerant-to-water heat indoor exchangers overcome the need for trace heating, anti-freeze and water-treatment chemicals.

Servicing is required at 10 000 h intervals, or every two to three years.

Jeff Fleming concludes, ‘The technical support from Oceanair has been excellent throughout. They are experts in Sanyo GHP technology and helped to train the hospital engineers in commissioning and optimising the systems.’

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