It all depends on where you are going to put it…
This is the most common type of fan and usually the least expensive. There are a variety to choose from, including some very stylish models, and they are usually less bulky in appearance.
However, they only operate on short ducting of around 1 metre, so are suitable for venting out of walls. They are not particularly effective when ceiling mounted as the ducting is not long enough, which leads to a build up of condensation. This turns to mould, leading to the destruction of the fan, and water marks on your ceiling. Left untreated, it can also affect the floor beneath the fan.
These operate on longer ducting so are suitable for wall or ceiling mounting, making them a more flexible choice, particularly as they are usually robust and reliable. They are more expensive than the axial fan, and tend to be larger, making them more obtrusive.
In line fans
This type of fan is usually located in a loft space, and operate well through longer lengths of ducting. Their location means the noise is less obtrusive, and, because you can’t see it, you can choose a larger model with more extraction power.
On the downside, if the fan fails you have to access the roof space to replace it. They are also the most expensive fan type.
12 volt fans
This refers to the power, or voltage, of the fans – both axial and centrifugal fans are available in this voltage. They are ideal for baths and showers, because their reduced voltage means you are unlikely to get an electric shock, should an incident occur.
However, these fans usually have a bulky transformer which needs to be accessed for maintenance, making them rather unsightly.
Cost is one of the biggest factors in fan choice. You do get what you pay for – the more expensive options tend to be more reliable and make less noise. With the exception of in line options, which are the most effective, the fans all have similar extraction capabilities.