S-Series Stack Based Ventilation
The S-Series e-stack ventilation units are designed for rooms
which have access to the exterior via the roof and usually
with occupancy levels of 30 or more persons. They
are ideally suited to halls but can also be used in
classrooms. The S-Series unit is square in plan, so hence the
name.
In winter the system uses a mixing ventilation strategy. Fresh
air is brought in through one half of the divided shaft immediately
above the S-Series unit, where it is then mixed with hot interior
air before being released into the room. Hot polluted air is
exhausted from the room through the other half of the divided
shaft. By using this e-stack strategy, the heat gains which arise
in the room are used for heating the incoming air during
the occupied time rather than a radiator which is required
in conventional upflow displacement ventilation mode to
preheat incoming air at low-level. The heat gains within heavily
occupied spaces (e.g. theatres or school halls) are often
sufficiently high that additional heating is not needed until the
external temperature falls to somewhere in the range 5-10°C,
depending on the U-value for the room.
Once the external temperature has increased such that air can be
brought in at lower level directly onto occupants without
pre-heating, the ventilation strategy for the system changes.
When low(er) level vents or opening windows are provided, a
displacement strategy is used; the low(er) level vents or windows
are opened, as well as the S-Series unit(s) and any additional high
level windows or dampers so as to maximize air flow and to minimize
build up of heat in the space. If low level vents are not provided,
the system just uses the high level S-Series e-stack units and any
other high level openings. However, rather than pre-mixing the
incoming fresh air as in Winter mode, the fresh air is simply
allowed to fall directly into the space.