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Preliminary 003
Access V4.X Configuration manual
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2019-05-13
2.4 Humidity control
Humidity control can be configured as Humidification, Dehumidification or both Humidification and
Dehumidification.
Activation:
Configuration > Functions > Function Activation
Configuration: Configuration > Functions > Humidity/Dehumidify
Settings:
Data & Settings > Humidity controller
Two humidity sensors can be connected, a room sensor for control and an optional duct sensor for
maximum limiting. The limit sensor can be omitted.
The humidity control is handled by a PI-controller.
The humidity sensors must give 0…10 V DC for 0…10
0 % RH.
Humidification
An analogue output is used to control a humidifier. The output will increase on decreasing humidity. A
digital output can also be used to start a humidifier.
Maximum limitation function using duct humidity sensor:
If the maximum limitation is 80 % RH and the hysteresis is 20 % RH, the controller output signal will
begin decreasing at 60 % RH. When halfway to 80 % RH (i.e. when at 70 % RH), half the output signal will
be damped. If the humidity in the duct still reaches 80 % RH, the entire output signal will be damped.
Dehumidification
An analogue output is used to control a dehumidifier. The output will increase on increasing humidity. A
digital output can also be used to start a dehumidifier.
Humidification/dehumidification
An analogue output is used to control a humidifier. The output will increase on decreasing humidity.
The cooling output Y3 will be activated for dehumidification through condensation. The output will
increase on increasing humidity. This signal overrides the cooling signal from the temperature controller
so the output can be activated for dehumidification even if the temperature controller demand is zero.
For good temperature control when using cooling for dehumidification it is important that the cooler is
placed first in the air stream so that the exchanger and heater can be used to reheat the air after
dehumidification.
Digital humidity signal
A digital output signal, "Dehumidification/Humidification", can be used for on/off control of
humidifiers/dehumidifiers. The output signal has an Activate value and a Deactivate value which are
connected to the humidity controller output. The signal is activated when the humidity controller output
rises above the set Activate value and is deactivated when the humidity controller output drops below
the set Deactivate value.