Bathroom extractor fans, axial or centrifugal.

[Gattopardo]

So the old fan in toilet room is quite blocked, also the fan has some interesting wiring so a metal light switch feels a bit buzzy.

Bought a cheap axial fan to fit as a replacement but have found that the original fan was a centrifugal and that was because the fan exits it to it's own duct and goes up, at a guess one floor. Will the axial be alright?

[Aunt Maud]

By the looks of the massive response, you'll be boldly going where no one has gone before.

[citoyen]

When I replaced the bathroom fan last year it was an axial, and it was all very easy, but that's because it was in the loft, fitted inline with a length of duct from the bathroom to the fan and then from the fan to outside.

Sounds like you might have difficulty installing your new fan in the same way.

[Tod28]

Axial fans have limited ability to generate sufficient pressure to blow air along a duct, the blades become aerodynamically stalled at relatively low back pressures.  Centrifugal fans (also called 'blowers') can generate pressure to move air through a duct.  Typically found in cooker hoods.

Typical for bathroom extraction eg https://www.tlc-direct.co.uk/Products/ADAV100T.html?ad_position=1o1&source=adwords&ad_id=45425533757&placement=&kw=&network=g&matchtype=&ad_type=pla&product_id=ADAV100T&product_partition_id=174053575267&test=finalurl_v2&gclid=CjwKCAjwmK3OBRBKEiwAOL6t1KEkyZP8Fxt2xsvCbpVkVD50zCz0_4y_JAVfo8RBrCP9E8Fyy_K_HRoCxTgQAvD_BwE

[Gattopardo]

The axial fan I have is similar to this

Removing the old fan was a nuaire one.  Think I shall replace it with a manrose ct100.


Anyone want an axialfan?

[Aunt Maud]

Mum might want it for her new not yet built bathroom.

[valkyrie]

You need a centrifugal, the axial fan will spin and make the right noises but not really move any air.

[Wombat]

Another vote based on many years of professional experience, for a centrifugal fan.  The axial one will indeed just stir the air round a bit and not actually move anything along a duct.

Sorry!

[rogerzilla]

Axials are fine when they blow straight through the wall.  In fact, provided you have a return air vent in the door (or a decent gap under it) the difference they make is astonishing in terms of condensation and mould.

[Nutbeem]

When we were getting lots of problems with condensation and mould in our bungalow I reckoned 3 of us showering up to twice daily was the culprit.

Replacing the bathroom axial fan with a decent centrifugal fan solved the problem. You can tell the difference straight away when you step out of the shower and the mirrors and windows aren't steamed up. When I fitted it I also put in metal ducting which I insulated to prevent condensation and angled downwards toward the wall vent so that any condensation that did occur drain out of the house.

I still recokon its one of the most effective DIY jobs I've done & would definitely say go for a good centrifugal fan.

[rogerzilla]

It's usually illegal as a DIY job now, except a like-for-like replacement.

[Nutbeem]

I'm sure you're right, and probably no bad thing, I've read a few stories about people electrocuting themselves or others through bodged DIY electrical jobs. Ours was safely and competently installed some time ago and I'm not expecting to get arrested.

You could always install the fan and ducting and get an electrician to connect the wiring and switch.

[rogerzilla]

I scrambled to get a lot of DIY wiring done before the end of 2005 when Part P came in.  It was a wet dream for NICEIC electricians.

[Kim]

I'm sure you're right, and probably no bad thing, I've read a few stories about people electrocuting themselves or others through bodged DIY electrical jobs.

Thing is, Part P does exactly nothing to prevent the really dangerous bodge jobs.  Which are pretty rare anyway - it's usually appliance faults that electrocute people.

[rogerzilla]

More people die from fires started by faulty wiring than from electrocution, so the Part P stuff is a bit pointless; you can still make poor connections on the DIY-permitted jobs.