ENGLISH
37
NT_51897201_RHE-AN_130516.docx
Free Cooling by night
8.11
This function is used during the summer to cool off buildings during the night by using fresh outdoor air.
This allows reducing the need to resort to air conditioning during the day.
To use the free cooling by night function, the information received from the outdoor probe (fresh air) and
from the discharge temperature probe is used. These two probes are present and integrated in the unit at
the level of the taps.
The free cooling is only active if the start-up conditions are satisfied.
Start-up conditions :
Less than 4 days have elapsed since the last start of the installation.
The outdoor temperature during the previous operation period exceeded the force limit of 22°C
(1).
It is between midnight 0:00 am
(1)..
and 7:00 am
(1).
In the morning.
The unit is stopped (the time programs – request for high speed (GV) or low speed (PV) – are
stopped).
A time program will be activated (
Start
) within the next 24 h.
If ALL the conditions are satisfied, the free cooling starts running. It runs for 3 minutes to make sure that
the temperature measurements are representative (by creating a movement of air in the ducts).
After three minutes, the controller checks the stop conditions.
Stop conditions :
The outdoor temperature is above 18°C
(1)
or below 10°C
(1)
(risk of condensation).
The discharge temperature is less than the stop value (18 °C).
The time programs (timer) for the normal speed, normal force run and the outdoor control are set
to
Stop
.
It is later than
7:00 am
(1)
in the morning.
If at least one of these conditions is satisfied after the first three minutes of operation, then the installation
is again stopped.
When the free cooling function is active, the fans run at maximum speed (it is possible to reduce this
speed by setting the parameters); the coil and heat exchanger control outputs are switched off. The
heating output remains inhibited for 60 min
(1)
after the function is stopped.
(1)
default values which can be changed by a parameter setting in ‘’expert mode’’
Antifreeze hot water coil protection
8.12
Frost protection for hot water coil, the water return temperature is transmitted to the controller by a probe. The
controller permanently generates a signal to the valve motor which allows preserving a sufficient hot
waterflow to prevent frost in the coil.
In case the water return temperature drops below the critical point (7°C), the fans are stopped and the
dampers (accessories) closed, an alarm is activated.
The antifreeze protection remains active when the fans are stopped.
External input for fire mode
8.13
The controller is configured to receive a fire contact. If the fire input is activated, the unit is stopped. When the
unit is stopped by the fire input, it can only be restarted after the alarm is acknowledged. It is possible to
configure an automatic restart. Two terminals are available for this input (see connection).
