During the ventilation start-up phase, it operates.
• If there is a free cooling or night cooling requirement, the recovery unit is shut down.
• There is a 1°C hysteresis between start-up/shutdown
Wheel seizing prevention
The PLC gives the order for the wheel to operate 1 minute every 4 hours.
Load shedding of the wheel
Load shedding of the wheel is possible using parameter P158.
225
Temperature difference for recovery unit run authorisation
Temperature
Return air < fresh air –P225
Return air > fresh air + P225
Heat recovery unit requirement
Cooling > 50% with a 50% hysteresis
On
Off
None
Off
Off
Heating > 50% with a 50% hysteresis
Off
On
Free cooling Night cooling
Off
Off
3.8 - Coil
The unit may contain a hydraulic or direct expansion coil, or an electrical heater.
This coil is configured using parameters P28 and P32.
The hydraulic coil may be a cooling coil, heating coil or mixed coil (heating or cooling according to the network temperature),
a direct expansion coil or electrical heater
28
Coil
32
Electric heater
3.8.1 - Mixed coil scenario
In the case of a mixed coil, the changeover may be made either via an on/off input or via the CMS (settable via parameter P162).
The changeover thermostat must be fitted by the installer on the mixed coil inlet, at a point where water is in constant circulation.
The changeover status (heating or cooling made) can be viewed via parameter P345.
162
Changeover selection
3.8.2 - Frost protection
The hydraulic coil frost protected by controlling the unit's supply air temperature. If this is below the threshold P248, the frost
protection fault is triggered and the isolation register is closed, the ventilation stops and the coil valves are opened 100%.
A frost prevention function is available once the unit is shut down (via the HMI, the CMS or a danger fault), or during the ventilation
start-up phase. It consists in leaving the hydraulic coil valve slightly open (settable value) to maintain water circulation (P260). This
opening is maintained constantly (including when the machine is shut down).
248
Hydraulic coil frost protection safety threshold
260
Coil valve opening percentage when shut down
3.8.3 - Electrical heater scenario
The control can operate an electrical heater comprising 2 on/off stages. These are operated in 3 stages (stage 1, followed by stage
2 and then stages 1 and 2).
Electric heating requirement
Stage 1
Stage 2
Stage 1+2
0 %
100 %
33 %
66 %
A minimum air flow rate is required to use the electric heaters (P126). If the flow rate is less than this parameter, the electrical
heater will not be able to start up and a "control limited" message will appear.
Electric heater configuration
32
Electric heater
126
Minimum flow rate for electrical heater operation
3 - FEATURES
EN-19
FLOWAY ACCESS
