RDF270.V.. fresh air unit controller provides different functions for equipment from basic with manual 1-/2-/3-speed fan to advanced with ECM fan, internal/external circulation and bypass function.

Internal/External air circulation

Some fresh air units only have a single duct and can be set to introduce fresh air from outside or circulate air via a built-in filter to maintain good air quality.

Dual duct fresh air units enable both internal and external air circulation.

Bypass function

This function is available in a dual duct fresh air unit and for external circulation only.

Without bypass function, outside air is preheated or precooled by extract air via the built-in heat exchanger in the fresh air unit. As a result, the outside air temperature is maintained prior to entering the indoor area. Little time is required to heat up or cool down outside air using heating or cooling units because the temperature deviation is little, thus saving energy.

Other situations require a bypass function.

If, e.g. the indoor area is too hot or too cold and the outside temperature is cooler or warmer, simply introducing the outside temperature to maintain comfort via bypass (or no heat exchange with extract air) is extremely useful and economic.

FAU-ECO function: (Eco-balance)

FAU-ECO is an automatic function to switch between internal and external air circulation, thus requiring that P25 is enabled or P25 = 1. In addition, to enable this function P02 must also be set to 2, then select Eco Mode via the power button.

When FAU-ECO is selected, the RDF270.V.. changes over air circulation between external and internal as per the time ratio defined in parameter P26. E.g., the factory setting (P26 = 1:5) means that within one hour, RDF270.V.. stays in external air circulation for 10 minutes, then switches to internal circulation for 50 minutes. The setting repeats while FAU-ECO mode is active.

This function can help users to maintain a balanced eco system by controlling the amount of fresh air inside buildings or apartments required to achieve good air quality for the living space.

For related applications, see Application setup based on selection of fresh air unit.