Swegon CLASS UNIT Operation & Maintenance Instructions Manual page 14

4.4 FROST PROTECTION
PLATE HEAT EXCHANGER
There are three strategies to protect the plate heat exchanger from freezing :
•
1 - Reduced supply air flow :
The heat exchanger is supplied with a frost protection sensor on the exhaust air (T3). If the exhaust air
temperature (T3) is >1°C and <+5°C :
• In airflow control mode and demand control, the supply air flow will modulate between 100% and 33%
(AFlow)of the setpoint (AFn)
• In pressure control mode, the supply air pressure will modulate between 100% and 50% (AFlow) of the setpoint
(AFn)
If the exhaust air temperature (T3) is <1°C, the supply air fans will stop until the exhaust air temperature (T3) is
>2°C for 5 minutes.
•
2 - Modulating bypass :
The modulating bypass is controlled by the exhaust temperature sensor (T3). If:
• Exhaust temperature (T3) >+1°C: bypass closed or controlled by free cooling function
• Exhaust temperature (T3) ≤ +1°C: bypass will modulate for the exhaust temperature (T3) to exceed +1°C.
The corresponding supply air temperature will drop due to a lower airflow through the heat exchanger
These Settings can be configured in ADVANCED SETUP
4.5 TIME SCHEDULE
The controller allows 6 time slots (channels) to be configured. For each day of the week,
the operation mode can be either AUTO (operate according to time slots) or OFF.
For each time slot select :
•
In airflow control mode: the airflow by selecting m³h K1 / m³h K2 / m³h K3 / OFF (stop)
•
In torque control mode: the torque by selecting %TQ K1 / %TQ K2 / %TQ K3 / OFF (stop)
•
In demand control mode :
• with only one 0-10 V signal (default) or with 2 signals to control the
supply airflow: the link LS (percentage of the nominal link, cfr m³/h Vmin
and m³/h Vmax in setup OR cfr %TQ Vmin and %TQ Vmax in setup) and
the rate of the exhaust airflow by the supply airflow.
• with one 0-10 V signal for supply and one 0-10 V signal for exhaust (via
advanced setup): one link LS (percentage of the nominal link) for supply
and one for exhaust.
•
In pressure control mode :
• Constant pressure on supply or exhaust: the pressure setpoint (percentage of the
nominal setpoint) and the rate of the exhaust airflow by the supply airflow.
• Constant pressure on supply and exhaust: one pressure setpoint (percentage of the
nominal setpoint) for supply and one for exhaust.
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Operation and maintenance instructions – CLASS UNIT TAC5