These ones have a natural ventilation setting where the shutters are open.
http://www.justfans.co.uk/advanced_search_result.php?keywords=stylvent&search_in_description=1&inc_subcat=1&x=0&y=0
Well done on sourcing the flow switch.
For an over-run timer try this:
http://www.justfans.co.uk/run-on-timer-5s-4hrs-p-707.html
or this:
http://www.justfans.co.uk/remote-timer-control-p-499.htm
Both should work if the flow switch is connected to the 'switched live' connection.
Hi y'all.
I found this recently, its a new product, comes well recommended.
At 26.5 dB(A) and with rubber motor mounts its the quietest bathroom fan so far.