Fan Coil Systems: Type FC Barcol-Air manufacture low noise, high efficiency fan coil units for today's modern buildings. All control types can be fitted with in-house pipework, wiring etc. carried out in the factory. Our comprehensive selection catalogue is available for Consultants use at design stage complete with all sound power levels, pressures, volumes and outputs.

FAN COIL UNITS

Design Recommendations

In order to make a proper fancoil unit selection, the whole air conditioning system must be looked at because sizing a fancoil unit is not just matching the room load. Other criteria which must be considered during selection are; the minimum room load, fresh air requirements, with or without reheat, 2 or 4-pipe system, zone size, flexibility and maximum noise level in the room, etc.
The cooling capacity which is supplied to the room is the sum of cooling energy available in the primary air and the cooling capacity of the fancoil unit. The way the primary air is supplied to the room determines a great part of the required fancoil cooling capacity. The fancoil capacity is defined by the entering and leaving air conditions (P = m x Cp x T). The leaving air condition is fixed (to offset the room load) but the entering air condition is dependent upon the way primary air is supplied.

The most common methods to supply primary air are shown in the figures below

System-1: This is the most energy efficient system. Primary air is supplied directly into the room and the recirculation diffuser is ducted to the inlet of the fancoil unit. For this case the cooling energy available in the primary air can be deducted from the room load. An additional benefit with this configuration is the fancoil unit can be switched off in situations where primary air only is sufficient to maintain the required room conditions or when ventilation only is required.
System-2: Primary air is supplied directly into the room and recirculation air is taken from the ceiling void. This is basically the same as system-1, however the cooling capacity must be higher because the temperature in the ceiling void is normally higher than in the room.
System-3: Primary air and recirculation air are both ducted to the intake of the fancoil unit. For this case, the entering air for the heat exchanger (M) is lower in temperature and less humid than at system-1. The required cooling capacity from the fancoil unit is equal to system-1, however the air volume must be higher to supply both the primary and fancoil capacities of system-1.
System-4: Primary air is ducted to the intake of the fancoil unit and recirculation air is taken from the ceiling void. This is basically the same as system-3, however the cooling capacity must be higher because the temperature in the ceiling void is normally higher than in the room.

When primary air is supplied near the intake of the fancoil unit, part of the primary air will be lost directly into the exhaust system wasting conditioned air energy.This is wasting energy and should be avoided.

To demonstrate the difference in energy consumption, we have made an energy analysis of the 4 systems. See the diagram below.