Modern Building Services

16 MODERN BUILDING SERVICES JUNE 2022 FEATURE AIR CONDITIONING, COOLING & VENTILATION C hillers however, have changed and the evolution in technology has given the sector a new lease of life, turning chilled water into a serious contender once more for many applications. The benefits of heating, cooling, heat recovery, water production, and direct expansion (DX) connectivity have seen VRF used extensively for building services, reducing capital expenditure and achieving low operating cost of a building. There are limitations, however. The capacities of modular VRF systems are generally limited to around 230kW and their footprint, when using multiple systems, can become quite large when available plant space is reducing. The amount of refrigerant circulating around a building can be high and the design hurdles to overcome potential refrigerant concentration legislation, if leakage occurs, can be expensive. This means that large building load demands often require something different. The chiller market has developed highly efficient alternative solutions which lend themselves to the demands of modern building design. This has taken what was once a predominantly cooling-only product for larger capacity projects to a multi-functional mid-to-large capacity competitor. Although the initial installation costs of a chilled water system may be higher than VRF, due to larger pipe diameters, pumps and flow regulators etc, the total cost of ownership over the lifetime of a system can still be competitive, and building design has little impact on the refrigeration circuit, meaning no issues with elevation or pipe length. A chilled water or hydronic systemworks by pumping water cooled by the chiller through a network of pipes inside the building, and uses water in the terminal unit heat exchanger in place of the refrigerant found in a DX system. While a DX system involves a heat exchange process of air to refrigerant and back to air, chillers introduce a further stage in the formof water.The advent of aluminiummicrochannel heat exchangersmeans thewater can be cooledwithout having to use the refrigerant circuit in suitable ambient temperatures, offsetting any reduction of efficiency due to the additional heat transfer process. The absence of refrigerant being moved around the building also means chiller-based systems bypass leak detection guidance (BSEN378), removing the need for leak detection systems in places of rest, such as hotels or student accommodation, which can add significantly to a project’s capital and maintenance costs. With a range of 49kW to 1.1MW, 4 pipe air-cooled EnergyPower chillers from Clint offer dynamic design potential. The units are able to provide cooling, heating and domestic hot water at the same time and with the same unit. They are suited to buildings with the simultaneous need of ambient heating, cooling and domestic hot water, such as hotels and multifunctional buildings with service and residential users. Models in the range covering capacities from49-190kWand 167- 634kWfeature scroll compressors with axial fans (EC inverter fans as an option) and plate heat exchangers. As an alternative to R410A refrigerant, they can be supplied with either R452B or R454B. Units for capacities from 278- 1133kW feature screw technology, shell and tube heat exchangers and axial fans, again with the option of EC inverter fans. As an alternative to R134a refrigerant, they can be supplied with R513A. For the best part of 30 years, chillers were in danger of being left behind as the growth and popularity of Variable Refrigerant Flow (VRF) solutions began to dominate the market for comfort cooling in commercial settings. Darryl Smith , managing director of AUK Distribution, explains why chillers now contain the technologies to fight back. Simultaneous operation – a chiller revolution