Humidity influence for TEh or TOa
If an extract air humidity sensor is available, the de-icing limit can be lowered,
because icing is reduced due to dry extract air. Configured de-icing limit refers to a
room / extract humidity value of 80% or higher. This value will be reduced
continuously by a configurable temperature drop until the room / extract humidity
value reaches 20% or lower.
Deicing with increased preheating
In case of possible de-icing, brine coil or ground collector are activated by the
outside air conditions. So they automatically assist the de-icing process.
Preheating with electric heater can be used to assist de-icing. This reduces the
efficiency of the heat recovery and uses electrical energy instead.
Especially when no reheating is available, it is recommended to use the electric
preheater, as otherwise reduced heat exchanger function will result in very low
supply air temperature.
As for normal preheating control, TSuAfPreHcl sensor is used. Electrical heater is
modulated to reach SpPreHDeicng setpoint. The preheater control runs in this
mode until de-icing is finished and switches back to normal operation running with
normal setpoint.
Deicing by with reduced fan speed started by differential pressure
switch
During deicing fan speed for supply fan and exhaust fan are set to configurable
values. For faster deicing, it is possible to set the supply fan speed setpoint even to
0%. In this case electric heaters in the supply air are blocked.
Deicing with reduced fan speed started by TEh or TOa
The temperatures have 2 adjustable limits. The higher limit SpTDeicHExg (stage 1)
starts deicing with the bypass damper only, while the lower limit SpTDeicFan
(stage 2) starts deicing with bypass damper and fan speed in parallel (2 stage
approach).
During deicing, fan speed for supply fan and exhaust fan are reduced to
configurable values. For faster deicing, it is possible to set the supply fan speed
setpoint even to 0 %. In this case electric heaters in the supply air are blocked.
Available parameters
Actual values
BACnet object
R/RW
Note
Deicing request for fan
DeicReqFan
BVAL,308
R
Heat exchanger differential pressure
monitor
HExgDiffPMon
BI, 77
BI, 94
BI, 111
BI, 128
R
Basic settings
BACnet object
R/RW
Note
De-icing mode configuration
DeicModCnf
MVAL,411
RW
1: None
2: Not used
3: Fans
4: Preh
5: Fans + Preh
De-icing, stage1 limit, preheat only
SpTDeicHExg
AVAL,378
RW
°C
De-icing, stage2 limit, fan
SpTDeicFan
AVAL,373
RW
°C
Activation time deicing
TiDeic
PINTVAL,146
RW
sec.
Application functionalities
Energy Recovery
5
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A6V10733786_en_c
