Bathroom ventilation

| I've a bathroom, including shower cubicle, that's about 4.3m x 2.8m x | 2.8m. There's no extraction so it gets kinda steamy... | | Doing the calculations: | | Room volume is roughly 34 cubic metres. | | General google-style advice suggests something like a 15x air change per | hour for a bathroom with shower... giving around 500-600 m^3/hr | extraction. | | That sounds kind of big, compared with the 100/150mm fans that screwfix | et. al have. | | Do I _really_ need such a large fan? Or will something more standard do?

Start with nothing and increase it as required. My bathroom is perfectly satisfactory with the window open two square inches, and I think I could get away with less.

In message , AJB writes

I reckon something more standard will do.

I our old house I fitted a 100 mm inline fan with about 3-4 m of ducting in the loft - rating was about 85 m^3/h. bathroom was smaller than your, about 20 m^3 - but at 15 changes an hour would have given 300m^3/h.

I found the fan was perfectly good, never ever thought it was insufficient. It was operated by a humidity sensor, so could come on run for as long as it needed