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
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
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.
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.
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.
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