Main parts

R model in the figure. In the L model, the parts are mirrored.

No.PartNo.Part
2aHeat recovery cell6aPost-heating resistor 
3aExtract air fan9aCeiling bushing for electric wires
3cSupply air fan10aControl panel 
4aFine filter for supply air11aInternal carbon dioxide and humidity sensor
4bCoarse filter for supply air11cCarbon dioxide sensor (optional)
4cCoarse filter for extract air11dHumidity sensor (optional)
5aBypass damper of the HR cell11eVOC sensor (optional)