I recently replaced a very old broan/nutone bathroom exhaust fan with a newer model (LPN80) and afterwards, I noticed that sometimes when I turn on the ceiling light, the fan makes 2 quick beeps. The light and fan are on 2 separate switches and everything appears to be wired properly. This is not covered anywhere in the manual and I called Broan to see if they had any ideas as to why this may be happening, but they were next to useless - couldn't tell me what 2 beeps means and tried to immediate deflect and blame. Google brought up nothing useful either. Note that the fan seems to be operating normally otherwise - turning on the switch for it causes it to turn on and perform as expected. Anyone else experience this before and found what caused it?

We're doing a complete renovation. is it possible to install the fan and connect up vents before drywall goes up so that no cutting is needed after? Do you just add the thickness of drywall and mount the fan 5/8 lower?