UK: Daikin EWAH~TZ air-cooled VFD screw compressor chillers, using HFO refrigerant R1234ze(E), have been at the centre of a major heating and cooling transplant at Basildon University Hospital.

The four-storey Essex Cardiothoracic Centre (CTC) at Basildon University Hospital houses the county’s leading facility for heart and lung operations, with four operating theatres, four catheter laboratories, MRI and CT scanning facilities, and two 24-bed wards for recovery and in-patient requirements.

The CTC’s ventilation and cooling systems, comprising two air handling units and two chillers sited on the roof, had been state-of-the-art when switched on in 2009, but had become unable to provide sufficient temperature and humidity control. The chilling capacity needed to be improved and the AHUs replaced at the same time because the original units had never achieved the required air-flow rates.

“The AHUs had air-on, air-off settings that complied with hospital technical memorandum (HTM) standards at the time,” explained Iain Oakley, Mid and South Essex NHS Foundation Trust’s project manager. “But we know that due to global warming we are often experiencing ambient temperatures in excess of 31ºC. There were many days when the cooling capacity simply wasn’t available to meet the demands of the theatres and cath labs.

“We also couldn’t reduce the humidity in the operating theatres, which affected the equipment, occasionally resulting in the theatres and cath labs having to be shut down on days when the humidity was too high, because we could not risk the equipment failing during operations.

Ellis Building Services were given a four-day weekend to remove the old equipment, then install and commission the new plant – working in a live environment.

“That was all the time the CTC would allow,” said Iain Oakley. “The theatres were shut down late on the Wednesday with work having to be finished on time because there was a list of operations scheduled to start at 08:00 am on the Monday.”