shower fan vent(butterfly flaps)

[den9112]

Hi, i have just instaled my shower fan and switched on and all works fine. However when the fan is running only one of the butterfly vents open ,the other is trying to open but never fully opened ,is this normal ,the fan is positioned on a board and is solid , i have a couple of feet of ducting at the inlet and a couple of metres running slightly down and out to the soffit. The fan is a greenwood airvac 5inch induct with timer . Any tips on getting the best out of it would be apreciated .Thanks

[Llan1observer]

if the second butterfly flap is fouling can't you give it a light sanding?

about a 20min run after shower should reduce condensation.

[den9112]

Just checked and they are not sticking ,only one of the butterfly flaps is basically shut all the time as if it is only doing 50%.