Access Configuration Manual

Recirculation is a function for distributing the air in the room using the supply air fan. The function can be used even when there is no heating or cooling demand.

When using recirculation control, the extract air fan stops (but can also be set to run) and a recirculation damper opens which allows the extract air to circulate back through the unit.

Recirculation is activated either via a digital input signal or by connecting it to the "Extra time channel 4" schedule:

• If a timer output for Low/Normal/High speed is activated during recirculation via Extra time channel 4, Low/Normal/High speed gets priority.
• If a timer output for Low/Normal/High speed is activated during recirculation activated by a digital input, recirculation gets priority.

Recirculation damper actuator can be connected either to a digital output or a modbus actuator.

Recirculation control can be configured as either air circulation (temperature control inactive) or air circulation with temperature control (only heating, only cooling or both heating and cooling).

Recirculation control has its own setpoint. However, the other settings are the same as for normal operation. e.g. if normal operation has been configured as room control, room control will also be used during recirculation.

The recirculation setpoint can be configured as constant or offset. Constant means that the recirculation setpoint will be used. Offset is based on an offset from the supply air setpoint.

To lower the temperature, it is possible to configure free cooling to be used during recirculation.

A max. room temperature can be configured for recirculation control. If the room temperature rises above the set value, recirculation will be stopped. When the

room temperature has fallen 1 K below the set max limit, recirculation will start again if the start conditions are still present.

It’s possible to configure the output value for each sequence when recirculation is active. The output can be configured to 0%, 100% Or Auto.

e.g. It is common that operation of the exchanger is not required during recirculation. In that case it can be suspended by settings Sequence output during recirculation to 0%.

During recirculation, the fan runs on "Normal" fan level. The level can be adjusted by the fan offset value.

e.g. The default setpoint for "Normal" fan level is 50% (manually control type). The speed can be reduced by entering a negative offset value: 50% (Normal setpoint) -10% (Offset) = 40% fan level during recirculation.

Related topics:

Air quality control