5.9.2 Passive Heat Exchanger, controlled (PltHExg21y)
The purpose of energy recovery is to absorb heat/cold from the exhaust air and
transfer it back to the supply air side. Energy recovery is usually used as the first
heating/cooling element. The control of the energy recovery can be advantageous
in the off-season depending on the required supply air temperature. Since the
passive heat exchanger itself cannot be modulated, a bypass damper (open/closed
or modulating) is used to control the supply air temperature.
Be aware, that the bypass damper closed position means maximum heat
exchange while open position means no heat exchange.
Depending on settings and prevailing temperature conditions, energy recovery unit
may also be selected to be used only heating or cooling energy recovery.
If the bypass damper is equipped with a binary output, it is closed, when the
controller output raises above 60% and opened when the controller output falls
below 30% (fix values).
Specific functionality for
piston air dampers
Until now normal and 0..10 V dampers were supported. Now also piston air
dampers can be controlled.
This function controls a thermal actuator for a free cooling bypass damper. Both
relays Q1 and Q2 are used: When one relay opens, the second is always off, i.e.
they never operate simultaneously.
Specific operation sequence:
To open the bypass, relay Q1 closes and the motor piston is powered for 150
seconds, the bypass is considered completely open and the relay is deactivated.
To close the bypass, relay Q2 closes and the motor is powered for 150 seconds,
the bypass is considered completely open and the relay is deactivated.
To avoid overheating the bypass motor, the relays are not activated again for 300
seconds to allow the piston motor to cool down.
Available parameters
Current values
BACnet object
R/RW
Note
Heat exchanger bypass damper position
Prio2: Fire / Smoke
Prio4: Heat exchanger fault
Prio5: Protection
HExgDmpBypPos
AO,105 (A1)
AO,114 (A2)
AO,123 (A3)
AO,132 (A4)
AVAL,384 (POS9)
AVAL,473 (AO1)
AVAL,480 (AO2)
RW
%
Heat exchanger bypass damper command
Prio2: Fire / Smoke
Prio4: Heat exchanger fault
Prio5: Protection
HExgDmpBypCmd BO,55 (Q1)
BO,70 (Q2)
BO,85 (Q3)
BVAL,246 (POS9)
BVAL,353 (Piston)
RW
0: closed, 1:
opened
Heat exchanger bypass piston damper Open
HExgDmpBypCmdOp
BO,104 (Q1)
RW
Prio5
Heat exchanger bypass piston damper Close
HExgDmpBypCmdCls
BO,105 (Q2)
RW
Prio5
Setpoint supply air temperature for heating
SpTSuHHexg,
AVAL,355
R
°C
Setpoint supply air temperature for cooling
SpTSuCHexg,
AVAL, 356
R
°C
Application functionalities
Energy Recovery
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