FAN COIL UNITS
As much as fan coils are typically about ducting on the supply air side, the return air path is equally important. The path should be clear of any obstructions, and the units can draw either from the ceiling void or a ducted intake. Installations where the fan coil unit supplies air from one space into another with no discernible air path between them should be avoided at all times.
Commissioning
The importance of commissioning a project cannot be understated and should be completed by experienced and knowledgeable engineers who understand the systems and the intent of the systems’ design. All fan coil unit manufacturers will include guidance in their
product instructions on what and how to commission their units and this should be followed closely. Consideration should be given to both a ‘Winter’ commissioning (of heating systems) and a ‘Summer’ commissioning to ensure the unit control and functionality is correct.
Usage Throughout the use phase of a fan coil unit’s life, there are steps
that can be taken to get the best use out of the unit. Firstly, simple controls should be used to keep any user education to a minimum. Some ask for an explanation of the fan coil unit controls to be printed and placed next to the wall controllers to explain their operation to those in the room. Whether the building uses fan coil units or not, there is always
a benefi t to educating occupants about energy-saving practices. Simple actions such as closing windows and doors, adjusting blinds to block direct sunlight, and avoiding unnecessary use of fan coil units can help conserve energy and maximise the building system’s effi ciency.
Installation
The installation of fan coil units is one of the best opportunities to build in quality to the M&E package of the project. Picking up from the design stage, the installation contractor should avoid value engineering fan coils with simpler controls, smaller units, or inferior quality components.
Once activities on site start, units should be installed in locations that allow access for servicing and maintenance to ensure the unit can kept in working order. Particular attention should be paid to the positioning of sensors, and to ensure that localised draughts from other fan coil units or other services are kept to a minimum. Manufacturers will qualify their units’ acoustic performance based on typical installations and it’s important these are followed in the performance is expected to be achieved. The generally accepted installation is spiral wound ductwork and should be used as the same diameter as the fan coil units’ spigots with fl exible ductwork being used on the last meter. Unused spigots should be considered in the context of the fan coil unit schedule issued by the manufacturer to ensure that in- duct air velocities are controlled. Pipework to the unit should be well insulated with all exposed parts of the hydronic system covered. Where pipework joins onto the unit, the insulation must extend over the drain tray to avoid condensation forming and dripping onto the ceiling below.
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As the use of buildings change and adapt over time, it’s likely that the demands on the building services for that room will also be impacted. Will the change require more heating, cooling, or ventilation, are all questions that building owners should consider.
Maintenance
Good maintenance starts with a plan, and this should cover both units’ locations, the schedule of work needed and the training and development of those completing the work. In the current age of facilities management companies, most building owners will outsource this work to third parties, but the levels or service off ered and skillsets available should be agreed up front. Regular training for building operators and maintenance staff should be conducted on the proper operation, maintenance, and troubleshooting of fan coil units. Well-trained personnel can identify issues early, perform preventive maintenance tasks, and ensure optimal performance of the equipment. Fan coil manufacturers should be consulted about installing enhancement features (such as UV germicidal lamps) that specifi cally target indoor air quality for their products. Whilst the cleaner air not only enhances occupant comfort and prolongs the lifespan of the FCU components, this has to be balanced with the impact on the fan coil unit itself. Highly resistive or fi ne fi lters (such as HEPA) should be avoided as they typically require stages of prefi ltering to avoid becoming quickly blocked resulting in severe degradation of the fan coil units’ performance.
The UK’s forward- thinking
government is continuing to build on its strategies for decarbon- isation, resulting in vast
opportunities for growth and
innovation in 2025. With measures in place to reduce heat pump costs and strengthen supply chains, the focus on sustainable electrifi cation of heating is clearer than ever.
www.acr-news.com • February 2025 27
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