User Manual

59
AUTOMATIC CONTROL
4 VENTILATION AND AIR CONDITIONING
CONTROL
BT Reason for energy savings
4.7 Heat recovery control (prevention of overheating)
This control function is to avoid overheating at
the heat recovery unit.
0
Without overheating control
There is no specific action to avoid overheating
10
Heat recovery is always on 100% and can
overheat the supply air flow, requiring additional
energy for cooling.
1
With overheating control
During periods where the effect of the heat
exchanger will no more be positive a control
loop between "stops" and "modulates" or bypass
the heat exchanger.
11
Temperature sequence control at heat recovery
prevents unnecessary recooling of the supply
air.
4.8 Free mechanical cooling
0
No automatic control
Supply air is always mechanically cooled as
required using active energy
1
Night cooling
The amount of outdoor air is set to its maximum
during the unoccupied period provided:
1) the room temperature is above the set point
for the comfort period.
2) the difference between the room temperature
and the outdoor temperature is above a given
limit.
If free night cooling will be realized by
automatically opening windows there is no air
flow control.
Night cooling (passive cooling):
During the night, heat stored in the building
mass is removed by cool outdoor air until the
lower limit of the comfort range is reached,
reducing the use of active cooling energy during
the daytime.
2
Free cooling
Both the amount of outdoor air and recirculation
air are modulated during all periods of time to
minimize the amount of mechanical cooling.
Calculation is performed on the basis of
temperatures
12
Reduces energy demand on active cooling of
supply air:
Maximum Economy Changeover (MECH):
Heat recovery is opened whenever the exhaust
air temperature is lower than the outside
temperature.
Production of chilled water with outside air:
(from supply air via cooling coils and coolant
directly to cooling tower).
Has priority (favorably priced energy) as long as
the outside temperature suffices for cooling.
3
H,x- directed control
The amount of outdoor air and recirculation air
are modulated during all periods of time to
minimize the amount of mechanical cooling.
Calculation is performed on the basis of
temperatures and humidity (enthalpy).
Maximum Economy Changeover (MECH):
Heat recovery is opened whenever exhaust air
enthalpy is lower than outdoor air enthalpy,
reducing energy demand on active cooling of
supply air.