"Tim Watts" wrote in message
...
Some of those inline fans can shift a fair volume - don't think "bathroom"
necessarily, think "inline fan" - the question is, how much do you want?
I've never been impressed with bathroom ventilation so I got a higher
rated inline fan for mine.

Fair point. I haven't calculated how much air I need to shift yet. The US
DOE has some guidelines, which some US whole-house fan makers think are a
bit high, so I'll do some more research and some sums and then revisit
inline fans. The ones I briefly looked at didn't come close to the airflow
of the US products.

Ultimately, there's only so much you can shift up a 4" duct and vent
(unless you were planning to put more or larger vents in each room?).

I'm rather liking another poster's idea of making a special loft hatch, with
a big fan venting directly into the loft space, at least to start with.
Ducting and multiple inlets might come later!

Thanks for your ideas.