Trane R454B chillers replace ageing rooftop units at York hospital

A hospital in York needed more reliable, energy-efficient cooling for its main air handling unit circuit. Two rooftop York YAES 0415 air-cooled chillers using R407C formed the original system. One of those units had already failed and the remaining chiller was carrying the load. Because this is a critical healthcare environment, the site team required a planned, low-disruption replacement.

The contractor Newsome selected two Trane Sintesis Advantage CGAF 105 HE LN air-cooled chillers. Each unit is specified at approximately 395 kW nominal cooling capacity and uses the lower-GWP refrigerant R454B. Each chiller contains two independent refrigeration circuits, which provides redundancy and reduces the operational impact of maintenance or a single-circuit fault.

Newsome's detailed comparison indicated a reduction in annual power consumption of roughly 28% across both new units versus the old chillers. A more detailed single-unit operating-profile comparison suggested an efficiency improvement of around 33% for one new chiller compared with one of the old machines.

Because the site is a live hospital, installation planning focused on minimising disruption and maintaining cooling availability. The failed chiller was disconnected first to stabilise the system. The main lifting operation to remove the old units and place the new chillers on the roof was scheduled on a weekend to reduce interference with hospital operations.

Work was phased so the first new chiller could be connected and commissioned before the second old unit was removed. During the lift, the remaining old chiller was isolated and disconnected to allow safe rooftop access. This staged approach maintained cooling capacity and allowed commissioning of one replacement before completing the second, reducing risk to building services.

Operational resilience and options considered

The two independent refrigeration circuits per chiller add resilience by allowing partial operation if one circuit requires service. The project team also assessed adiabatic spray options as an upgrade path for existing equipment, but concluded a full chiller replacement would deliver the largest efficiency and resilience gains for the AHU cooling circuit.

Newsome, founded in 1973, specialises in industrial temperature and humidity control solutions. Its services include rental and maintenance across sectors such as food and drink, plastics, chemicals, manufacturing, leisure, building services and pharmaceuticals. For this project Newsome handled the site review, comparative analysis, logistical planning and the phased rooftop replacement.

Facilities with ageing chillers serving critical loads can gain efficiency and resilience by comparing retrofit upgrades against full replacements. When a building must remain operational, phased replacement and weekend lifts can reduce disruption. Selecting chillers with multiple refrigeration circuits and lower-GWP refrigerants can improve redundancy and reduce future regulatory or environmental exposure.