The electric duct heaters are suitable for heating the supply air in rectangular ventilation systems. The heating registers are used for air heating in the heating, ventilation and air conditioning systems in various rooms.

The housing and the switching device are made of galvanized sheet steel and the heating elements are made of stainless steel. In the 400x200 to 600x350 models, the heating elements are provided with extra fins to increase the heat exchange surface.

The heating registers NK are equipped with two overheating protection thermostats:

• The main protection with automatic reset and the tripping temperature above +50°C. After cooling, the thermostat automatically closes the heating register control circuit.
• The alarm protection with manual reset and the trigger temperature above +90 °C. Once triggered, the heating register can only be switched on after the alarm has been manually reset.
• The thermal contacts are provided with terminals for external connection.

Each standard size has multiple performance options. The higher performance can be achieved by connecting the heating registers one after the other in series. In the heating registers with an output of over 27 kW, the heating conductors are connected in groups of 9 kW each. Each group consists of 3 heating conductors that are connected with a Δ circuit.

The heating register is installed using the flange connection. The assembly must be carried out in accordance with the air flow direction (marked by an arrow on the heating register). The heater coils can be mounted in any position except with the electrical shield facing downwards as this creates a risk of condensate ingress and short circuit.

It is advisable to mount the heater register so that the air flow is distributed evenly on average.

An air filter must be installed in front of the heating register to protect the heating elements from contamination.

The recommended distance between the heating register and the other system elements should at least correspond to the diagonal of the heater. Ie the distance from one corner to another corner in its air duct part.

The duct heating registers are designed for a minimum air flow speed of 1.5 m/s and a maximum air operating temperature of +40 °C. When using the fan speed controller, the minimum air flow through the heating register should be ensured.

The power supply to the heating register must not be switched on when the fan is at a standstill!

For trouble-free and safe operation of the heating registers, the control unit is recommended, which ensures complex control and protection: