ACR Journal

DX SOLUTIONS DX FLEXIBILITY IN A POST-PANDEMIC WORLD The importance of e ective ventilation in our buildings has taken on greater significance as we rebuild after Covid. Careful planning during the design stage can help realise the full potential of an HVAC system. Many people think of air conditioning as purely a method to cool occupied space, even though heat pumps have been available since the 1970s producing both cooling and heating. As an industry we may know more about heat pumps, heat recovery and energy transfer, but do we understand design benefits as well as we should? The functions and features of a building include a mixture of services, including air conditioning regulating temperature, boilers generating hot water, and air handling units introducing fresh air whilst removing the stale air and improving indoor air quality. By understanding VRF heat recovery, energy recovery can be realised across di erent types of products. Martyn Ives, distribution sales & technical services director at Fujitsu General Air Conditioning UK, looks at how the flexibility of DX kits can play a key role in improving indoor air quality and increasing efficiency. Energy saving through innovative design Fujitsu direct expansion (DX) kits enable other manufacturers’ air handling units (AHUs) and fan coil units (FCUs) to be incorporated into a VRF system, or be connected to a VRF outdoor unit to control outside air ventilation or room temperature. AHUs can, in most cases, include a DX or hydronic coil to provide either the tempering of fresh air or full air treatment. Wide operating envelopes allow the coil to work with supply air temperatures down to -7°C in heating, greatly reducing the need for expensive electric pre-heats. Heat exchanger capacity can be between 5kW-50kW, due to the ability to connect two electronic expansion valve (EEV) units in parallel, allowing the creation of full systems up to 150kW. The use of an air conditioning system as a method of climate control within an AHU generally outweighs other methods in e ciency and installation costs. It is also important as an alternative if a site has limited electrical supply, as air conditioning has low start-up currents, inverter control, and better output to input energy ratio. Integrated heat pump systems within AHUs are a good accessory, but energy- saving functions such as preheating a building before occupancy on a cold morning, without introducing cold fresh air, are limited. Benefits can be maximised by using heat recovery VRF instead of a heat pump, with the energy expelled or absorbed by each type of DX coil used elsewhere. Controllability is key to integrating VRF to other applications. AHU fan speed control, defrost signalling, error monitoring and air flow detection are all examples of direct integration and connectivity to Fujitsu’s range of local and centralised controllers, as well as building management systems, allows comprehensive integration. In addition to Fujitsu’s VRF DX solutions, split system kits make application into smaller specifications easier and cost- e ective, spanning a range of 3.5kW to 22kW with capacity demand control. If we remember that air conditioning doesn’t have to stand alone, we can open up the full potential of improved indoor air quality and building e ciency through energy recovery. To discover more about the extensive Fujitsu product range, visit https://www. fujitsu-general.com/uk / or email sales@fgac.fujitsu-general.com The design flexibility of the Fujitsu DX expansion kits allows both stand alone and heat recovery applications CMYK / .ai CMYK / .ai CMYK / .ai acrjournal.uk 19