English
0%
100%
Economizer
Room Temp.
Winter
Setpoint
FreeH_Diff.
FreeH_Offset
compressor
operation
0%
100%
Economizer
Room Temp.
Summer
Setpoint
FreeC_Diff.
FreeC_Offset
compressor
operation
0%
100%
Economizer
Room Temp.
Winter Setpoint -
Dead Zone/2
2
Dead Zone
Winter_diff. -
compressor
operation
The blast temperature minimum limit neutralizes the damper modulation, forcing it to close.
Caution
11
SysAer
3.6.1. SUMMER FREECOOLING
3.6.2. WINTER FREEHEATING
3.6.3. WINTER FREECOOLING
The summer freecooling is allowed only
if: Outdoor Temp < Room temperature –
Freecooling/heating differential, to ensure
that outdoor air is cold enough to cool room
air.
The opening of the external damper is
controlled by the room air temperature as
illustrated in the following figure.
In standard operation, Summer STP = 24°C, FreeC_Offset = -2°C, FreeC_Diff = 2°C
If the offset is set null or positive, freecooling can be made to start after the set point.
The winter freeheating is allowed only
if: Outdoor Temp > Room temperature
+ Freecooling/heating differential, to
ensure that outdoor air is hot enough to
heat room air.
The opening of the external damper is
controlled by the room air temperature
as illustrated in the following figure.
In standard operation, Winter STP = 21°C, FreeC_Offset = 2°C, FreeC_Diff = 2°C
If the offset is set null or negative, freeheating can be made to start before the set point.
Winter freecooling is useful in shopping
centres during operation in winter,
where overcrowding inevitably causes
temperature to exceed the set point,
meaning the place needs cooling as
opposed to heating. Therefore, for the
job of cooling, external conditions are
exploited, which are almost always
favourable for this purpose in winter.
The summer freecooling is allowed only if: Outdoor Temp < Room temperature – Freecooling/heating
differential, to ensure that outdoor air is cold enough to cool room air.
The opening of the external damper is controlled by the room air temperature as illustrated in the following
figure.
The set point and differential (also considered the dead zone/2) are the ones relating to winter mode.
In SUMMER FREECOOLING and WINTER FREEHEATING situations, the normally closed (at minimum position)
external damper starts to mix external air with room air in an attempt to move the work point as near as
possible to the set point, hence turning off as many devices as possible switched ON for cooling or possibly
heating purposes.
The ideal condition would be when the desired temperature or enthalpy is reached just by modulating the
damper.
There is an option in the Service menu to select the minimum damper opening when the unit is ON.
