Zehnder EASY 5.0
59
20.2. Overheating protection via safety thermostat THS
The supply air electric heating coil is controlled by the supply air fan feedback signal to prevent overheating of the
heating element in case of a fan breakdown:
■
If the supply air fan feedback is idle and there is a request to activate the heating resistor, it will not be activated
■
If the electric heating resistor is activated and the supply air fan feedback drops, then the heating resistor will be
deactivated.
This control does not exist for the electric fresh air preheating coil or in the case of a hot water heating coil.
The electric heating coil is equipped with an overheating safety thermostat set at +100°C, which protects the machine
from accidental overheating (e.g. static relay failure). The overheating thermostat cuts off the power supply to the coil
by opening the control circuit of contact transmitter K1, which activates the alarm (63) “Electric coil overheating” and
stops the operation of the unit.
Z-MASTER-V1122-CSY-INM-Zehnder Easy5.0
PWM
100%
100%
75%
75%
50%
50%
25%
0%
25%
Heating requirement calculated by the PID according to the difference between the setpoint temperature and the temperature
measured at the supply or return depending on the temperature control mode used
Status of the DO output for controlling the electric heating coil for different calculated PWM values
time
