Zehnder EASY 5.0
9
5. Definition of thermal sequences
5.1. General
The temperature control is defined by 3 different thermal sequences illustrated by a pictogram visible from the main
screen (the size of the coloured area indicates the calculated requirement of the sequence):
■
Cooling sequence (management of the cold coil: BF cold water coil, DX or DXR direct expansion coil, CO coil
depending on version).
■
Recovery sequence (managed by rotary or plate heat exchanger depending on version)
■
Heating sequence (management of the heating coil: electric coil BE, water coil BC, changeover coil CO,
reversible direct expansion coil DXR according to version)
Each sequence is managed by its own PID parameters, and each sequence is connected to an analogue output (AO)
(see electrical diagram for the relevant machine).
In the case of a rotary heat exchanger, the recovery sequence depends on the speed of rotation of the wheel: the faster
the wheel turns, the greater the heat recovery. When it is not operating, there is no heat recovery, and this is also the
case when running in free cooling or free heating mode.
In the case of a plate heat exchanger, the recovery sequence acts on the opening angle of the bypass flap: the more the
bypass closes, the greater the fresh air volume passing through the exchanger and the greater the heat recovery. The
bypass also provides anti-icing (specific PID parameters), free cooling and free heating functions.
These 3 sequences work in succession according to the following descriptive diagrams.
Thermal sequences with heat recovery requirements:
Z-MASTER-V1122-CSY-INM-Zehnder Easy5.0
10V
Cooling coil output
Cooling requirement (summer)
Temp. Measured < Setpoint
+
Temp. Outdoor > Return temperature
Heating requirement (winter)
Temp. Measured > Setpoint
+
Temp. Outdoor < Return temperature
Heat e
xchanger/b
ypass output
Heat e
xchanger/b
ypass output
Heating coil output
0V
Cooling coil
Heat exchanger
Cooling coil
Cooling
+
Cooling recovery
Recovery
of cold
Recovery
of heat
Heating
+
Recovery of heat
Cooling
Heating