Instruction Manual ZHK
V07-21.0
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Plug fans
When using this type of fan (fan with direct-coupled motor-wheel), a frequency converter is neces-
sary to reach the operating point.
7.6 Electric heaters
An electric heater is designed to heat the airflow, which is recorded on the technical data sheet,
from the specified air inlet temperature to the air outlet temperature. EUROCLIMA provides electric
heaters with one or more stages according to customer requirements.
The control of the electric heater provided by the customer can be considered in several ways:
-
On-Off at single-stage electric heater (this type of control decreases the lifetime of the electric
heater under circumstances significantly)
-
On-Off at multistage electric heater
-
Continuous (e.g. with suitable thyristor control)
WARNING!
Fire risk!
With the electric heater in operation, the heating elements increase to a tempera-
ture of several hundred °C.
In the event of malfunction, for example, a heater in operation without adequate
airflow, inadmissible temperatures could occur. Furthermore, plastic parts, for ex-
ample, filters, gaskets and droplet eliminators etc., which are close to an electric
heater could become damaged or even catch fire. This could lead to the spread
of fire and significant damages to the wider building.
In order to avoid the above stated risks, EUROCLIMA provides, as standard, electric heaters with
two independent safety thermostats.
7.6.1 AHUs equipped by EUROCLIMA with control
Units, which are supplied by EUROCLIMA with control, are limiting the supply air temperature to a
default value of 35 °C.
This execution and function, as specified below, is supplied by EUROCLIMA.
Control-side limitation of the air temperature beyond the electric heater
The control of the electric heater always regulates the temperature of the air passing through the
heater so that it never exceeds the permitted air temperature in the AHU (40 °C, if not differently
specified in the technical data). This item must be specially and closely monitored, when the AHU
is only operated with a partial air flow. For example, in times of reduced use of the building.
WARNING!
As the heat output of an electric heater is generated very quickly and at full ca-
pacity at ON-OFF operation, there is a significant risk of overheating of the AHU,
which contributes to the damage of several components. This risk occurs espe-
cially at low air flows.
For this purpose, the air handling unit is equipped with a supply air sensor, which directly
measures and monitors the air temperature generated by the electric heater. The control engineer-
ing is used to ensure that the heating power of the electric heater is controlled so that the tempera-
ture remains within the permitted air temperature levels in the AHU.
Avoid overheating of AHU components by residual heat of the electric heater
In order to avoid excessive heating of components by residual heat of the electric heater, this con-
trol ensures that fan motor keeps on running for at least 5 min after cutting off of the electric heater!
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