Kitchen Ventilation - Air Vent Versus Extractor Fan

[Gyvybe]

Hi,
Could someone be so kind and explain the difference between a simple air vent in the kitchen wall and an extractor fan - do they require different openings?

Our kitchen has a simple grill vent installed in the wall but there's still too much moisture / condensation and my husband insists we install an extractor fan instead. Will we get any benefits from installing it?

And with most vent openings being rectangular in shape, how do we make the hole round to fit the fan? Do we need to call a builder to increase the existing hole, or are there easy ways to do it?

Maybe someone came across an extractor fan that fits into a rectangular opening? A link would be appreciated!

Thank you!

[Old_Geezer]

Unless I'm missing your point surely the obvious difference is that with a vent you are hoping the damp air will find it's own way out whist with a fan the air gets guided out ?

You can get square fan units. If you need a round hole then depending on size you either chisel out the sides to round the hole off, or cement the corners to achieve the same. One usually uses a round vent pipe & fittings.

Take a look at your local DIY sheds to see what they're selling.

[The Builder]

The "hole in the wall" is simply passive ventilation. Air just flows naturally, but sometimes the wrong way ........... i.e. draughts.
Mechanical extraction is "active", and much more efficient in clearing water vapour.

Assuming your square hole is at least 100mm wide, fitting a standard fan is a simple DIY job.
To avoid much bashing and cementing, make up something known as a "pattress". Just a piece of MDF big enough to cover the existing hole.
Drill a 100mm hole in the MDF, and fix the fan to it. Fix the pattress to the wall, and you're done.

Done mechanically, but you have to wire it up.
Because it's in a kitchen, it has to be done by a registered electrician. You could do it yourself, but you'd have to fill out a form and get Local Building Control (Building Inspector) in to witness the work........... really not worth the trouble.
A registered (known as a Part P) electrician can avoid all that faff.
You'll also need an isolating switch as well, but that can go at the top of the wall out of the way. Have a fan with a little pull-cord if you like, but you must have the isolator.

Extraction is rather like insulation or cheese.......... you can never have too much of it. ;o)

[Alston]

Mr Builder....I didn't think it was necessary to get a registered electrician to fit an extractor fan. Surely one can just plug it into an electrical socket.

[The Builder]

Of course, Alston, you're absolutely right.
I should have mentioned it. I was thinking only of the "normal" way of doing it with a connection into the lighting circuit.

It just shows how easy it is to over -complicate things sometimes.
There's always another way :o)

[Alston]

Thanks TB for agreeing with me. Nevertheless, it is better and safer to have an extractor fan which is connected to it's own dedicated 'plug'. My fan is mounted in the kitchen window and is wired into a 'socket' which is off the lighting circuit and is 'ceiling mounted'.