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9.6 Heating
9.6.1 Heat exchanger
8.6.1.1 Defrosting the rotary heat exchanger
In environments where the extract air can occasionally be
humid, the defrosting function can be activated to protect
the heat exchanger from frosting. The function continu-
ously monitors the condition of the heat exchanger rotor
to prevent condensate from freezing in the rotor passages
and clogging them.
The function requires a separate pressure transducer
(preset for heat exchanger defrosting) wired to the control
unit inputs for external BUS communication and connec-
ted by hoses to the pressure measuring tappings of the
unit.
See special installation instruction for the TBLZ-1-23-aa
Pressure sensor.
The pressure drop across the rotor must then be calibra-
ted to establish a reference pressure drop for monitoring
purposes. See 7.4.3 Calibration - Heat exchanger.
When the function is activated the pressure drop across
the heat exchanger is continuously measured and the
value is compared with the calibration value. If the pres-
sure drop exceeds the preset limit value, a defrosting se-
quence is implemented where the rotor speed is gradually
ramped down (ramp time of max. 4 minutes) to the speed
at which the pressure drop across the heat exchanger has
decreased to half of the preset limit value. The rotor speed
can be 0.5 rpm but not slower. During the defrosting op-
eration, warm extract air thaws any possible ice coating. A
time delay of 4 minutes gives the heat exchanger a chance
to dry, before the rotor once again is ramped up (ramp
time max. 4 minutes) to its ordinary speed.
The max. duration of the defrosting operation is 30 min-
utes. If the pressure drop has not decreased within this
max. duration on six occasions during a 24-hour period,
an alarm is tripped.
Note that the heat exchanger performs less efficiently
while defrosting is in progress and that the supply air tem-
perature will decrease downstream of the heat exchanger.
Settings:
Value
Defrosting
30
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Setting
Factory
range
settings
Inactive/active Inactive
INSTALLATION
FUNCTIONS
*FUNCTIONS*
TEMPERATURE
AIR FLOW/PRESSURE
FILTER
OPERATION
HEATING
COOLING
HUMIDITY
IN/OUTPUTS
IQnomic Plus
ALL YEAR COMFORT
OPTIMIZE
Defrosting function with separate pressure
transducers, in principle
We reserve the right to alter specifications without notice.
GB.GOLDLP.170830
*HEATING*
HEAT EXCHANGER
PRE/REHEAT
HEATING BOOST
EXTRACT AIR
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