Bathroom extractor fan size

Explosive_Cornflake

I was in Australia a few months ago and I notcied the extractor fans in bathrooms were great. They're much bigger than what you normally see here.
For example, this is 250mm (10"), but from what I can see you can only get 4" ones here. Is there a logical reason for this, or does anybody here carry large ones?

coylemj

How will you be venting to the outside? If it's via a roof tile then that big fan would be OTT as you would need a correspondingly big roof vent. For the motor to do it's job and not be stressed, the vent needs to be able to handle the airflow, otherwise the motor will overheat. So think about the venting before you go buying a bigger fan.

salmocab

Plenty of bigger fans available but bigger doesn’t necessarily mean better, fans are measurable in how much air they shift.

Btw a 20 dollar fan from bunnings is likely a piece of crap

Lumen

Australian building regs require higher extract ventilation airflow rates (25L/s vs 15L/s in Ireland AFAIK).

Modern small (100mm) fans can achieve 25L/s (90 m3/hr), particularly inline ducted fans, and 150mm can do so easily, so could be a historical thing.

Maybe fans burn out more easily at 40C than they do at 20C, so a larger fan moving more slowly, with a better cooled less compact motor, could make sense.

This site has a decent layperson's guide: https://www.extractorfanworld.co.uk/choosing-a-bathroom-extractor-fan-123-c.asp

colm_c

I have one in my bathroom, which has a booster unit in the pipework in the attic, which literally sucks the steam out.

Get the right one and you won't have any condensation.

As said before, don't go cheap, they just don't have any power.

Explosive_Cornflake

Good advice from all, thank you.

I don't have one currently, but i'm moving my shower to the other side of the bathroom.

Alkers

Have a look at a humidity controlled fan which will come on for steam regardless of the light and will stay on until the room is clear. Most have a toggle switch also if you want to extract air for other reasons than steam

Calahonda52

Just to keep the science right here and clear up a common misconception: we are not speaking about shifting steam, it is water vapour.
Water needs to be boiling to generate steam, and that process, called the heat of vaporisation of water, at 2,200 kJ/kg is a huge amount of energy, which is given back when the steam condenses back to water vapour, which is why steam burns are so dangerous.

dathi

Calahonda52 wrote: »

Just to keep the science right here and clear up a common misconception:
Water needs to be boiling at 100C to generate steam,

assuming you are at sea level if you are sitting on top of carrauntoohil with your stove it will boil at 96.6C;)

Calahonda52

Originally Posted by Calahonda52 View Post
Just to keep the science right here and clear up a common misconception:
Water needs to be boiling at 100C to generate steam,

dathi wrote: »

assuming you are at sea level if you are sitting on top of carrauntoohil with your stove it will boil at 96.6C;)

This is not a fair representation of the misconception i was speaking about.
selective editing of what I originally posted shows a lack of integrity, and IIRC is against the rules here.

In any event you are going on my ignore list, as is your fan club

Loraco

Hi All,

I hope you might have some advice! I know absolutely nothing about extractor fans (or any type of diy if i am honest) but I have been having serious problems with damp and condensation in my bathroom and the fan that is installed i think is a basic cheap model and is doing nothing. Would anyone have any advice or recommendation on where I can get a high powered fan that will clear the room instantly after the shower? I am also about to get an ensuite done (not currently used) which has no window so i need to get one for there also. Any advice or info would be greatly appreciated!

Alkers

Google a humidity controlled extractor fan.
How is your existing fan setup? Does it vent through a wall / ceiling / long duct?
Even with the fan, you need a source of fresh air to replace the humid air