Configuration Manual

Version Document
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001
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ccess V4.X Configuration manual
19 (56) 2018-07-11
Defrosting 1
Defrosting is activated either when the digital signal ”Defrosting” is activated or
when the value of the analogue input ”Defrosting temperature” falls below the
defrosting limit (-3°C), or when the analogue signal ”Exchanger extract air
pressure sensor” rises above the set value for the current pressure. It is
deactivated when the digital signal is reset, or alternatively when the analogue
signal exceeds/falls below the limit value plus a settable differential.
When defrosting:
A PID-controller compares the defrosting setpoint with the signal ”Defrotsing
exchanger”. The smallest of the output signal from this controller and the output
from the ordinary controller is used as output to the dampers.
Defrosting 2
Defrosting is activated by measuring the pressure difference over the exchangers
extract/exhaust side. The differential pressure transmitter is auto calibrated by the
system to obtain the correct pressure in relation to the airflow.
Manual calibration is possible, e. g. after cleaning of exchanger. Defrosting is
possible with by-pass or stop defrosting, adjustable in the display.
Defrosting is stopped when the desired, adjustable decrease in pressure over the
heat exchanger is obtained.
If the decrease of pressure does not happens during defrost cycle, the air handling
unit is stopped and an alarm is shown in the display.
Liquid exchanger
Control
A mixing valve in the exchanger circulation system is controlled by the analogue signal
”Exchanger” and digital output (“Sequence-A pump”) for pump control and/or signal
(“Sequence-A start”) for start heating.
Defrosting 1
Deicing is activated either when the digital input sensor ”Defrosting temperature” is
activated, when the value falls below the deicing limit (-3°C). It is deactivated when the
digital input is reset or the analogue input rises above the limit value plus a settable
differential.
On deicing:
A PI-controller compares the deicing setpoint with the signal ”Defrotsing Exchanger”. The
lesser of the output signal from this controller and the output from the ordinary controller is
used as output to the actuator.
Pump indication
A feedback from pump (“Pump sequence-B”) can be used, running indication or
alarm indication (“Feedback sequence-B”).