Coachman Ventilation

Switch S2 (intake) gets it going - the middle LED comes on and it settles into "comfort mode", the quietest, lowest extract setting. From there, S1 (extract) and S3 (intake) step the fan through 6 speeds, roughly 3.7 up to 24 m³/min. Leave it running for an hour at the top speed and it'll automatically ease back down to the lowest setting to save power.

There's a boost option too - hold either S1 or S3 for around 3 seconds and it'll run flat out for 5 minutes before dropping back to whatever speed it was on beforehand.