I wonder if anyone can help?
I've got a bathroom and en-suite shower on the top floor. The original
extractor fans go through the ceiling and duct out into the loft and through
a ridge tile. The old ducting system was ripped out years ago during a
renovation and now I have the task of replacing it.
I'm looking at placing a standard fan in each room (with timer/humidistat)
with the ducting from each fan terminating into the one ducting which then
goes out the ridge tile roof.

My concerns are with the positioning of the ducting and the chances/problems
of condensation dripping back down the ducting and through the fan. Another
concern is extracting from one room into the other room rather than through
the roof - do I need to install a valve or something?

Any advice and also any links to schematics on installing extraction systems
appreciated.