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5.9.2.1 ERC De-Icing (passive, controlled)
A6V10733786_en_c
Passive Energy ReCovery units are basically just heat exchangers. They receive
warm and humid air on one side and cold on the other which will eventually
cumulate ice on the surfaces when the conditions are suitable for that. Passive
element usually starts to cumulate ice already close to zero Celsius degree
Detecting ice on the heat exchanger or in the ductwork
Detecting ice on the heat exchanger or in the ductwork is possible:
●
with exthaust air temperature sensor TEh. This is not a real indication, but an
expectation that ice is expected to build up.
Deicing with TEh sensor starts when TEh is below the limit.
The end of the de-icing phase cannot be detected and is estimated via timer.
●
with a differential pressure switch over the heat exchanger. This possibility
does not detect ice built up in the ductwork and does not safely work on all
types of heat exchanger. If exhaust air temperature sensor and differential
pressure switch are installed, the differential pressure switch is used to start
de-icing.
–
Deicing is active as long as the differential pressure switch is active.
●
with outside air sensor TOa. This is used when no exhaust air sensor and no
differential pressure switch are available. It is also only an expectation that ice
has built up.
–
Deicing with TOa sensor starts when TOa is below the limit.
–
The end of the de-icing phase cannot be detected and is estimated via
timer.
De-icing the heat exchanger
De-icing is possible by:
●
Opening the bypass damper, so that the exhaust temperature increases
●
Reducing the supply fan speed, so that the load of cold air incoming is
reduced, increasing the exhaust air temperature.
●
PI control exhaust temperature to maintain a minimum exhaust temperature
●
Preheating the outside air, increasing the exhaust air temperature
De-icing modes
The deicing mode can be configured as:
●
No deicing
●
Increase bypass damper position to a fix value
●
Increase damper and reduce fan speed
●
Increase damper and increase preheating
●
Increase damper, reduce fan speed and increase preheating
●
ERC maintain minimum exhaust temperature *
●
Maintain exhaust temperature and reduce fan speed *
●
Maintain exhaust temperature and increase preheating *
●
Maintain exhaust temperature, reduce fan speed and increase preheating*
*: Modes shall not be used if the damper is equipped with open / close control.
Deicing with ERC and with preheater are running in parallel. Deicing with fan
speed is running in parallel or with 2 stage, see below.
Application functionalities
Energy Recovery
101 | 170
5
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