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Installing an Extractor Fan in Your Bathroom

By: Chris Hogan MSc - Updated: 20 Dec 2016 | comments*Discuss
 
Extractor Fan Bathroom Odours

Installing an extractor fan in a bathroom is an excellent way of reducing condensation, which leads to damp problems. Damp can leave marks on the wall which painting over won’t hide, it can encourage mould growth or at worst lead to plaster becoming permanently damaged.

In a modern home, or one that’s been recently renovated, this shouldn’t be an issue. This is because building regulations have required fans to be fitted in new properties for many years. They should be connected to the light switch so that they come on automatically, then continue running for around five minutes after the light has been switched off. This of course helps to dispel odours as well.

Hiring an electrician is necessary

If your home is too old to have an extractor fan you can fit one yourself. The problem, as with any other electrical work in the home, is that it is getting nearly impossible for anyone other than a qualified electrician to do anything other than swap a bulb. And although the home might have been built before the regulations come into force they still cover new work in old houses. So your electrician will have to follow the regulations.

To be honest, if you are reading a site aimed at basic DIY, as this one is, then you’re probably not going to be knowledgeable and confident about electrics. In that case employing a qualified electrician is exactly the right thing to do. What we can do here is explain the other work involved so that you can do as much of it as you can, cutting the cost of the project overall.

Different types of bathroom extractor fan

From a DIY point of view there are three main types of extractor fan that can be used in a bathroom. Regardless of the type you decide to fit, the recommended minimum flow rate for a bathroom is fifteen litres per second, so make sure you buy a fan with that rate or higher.

The simplest to install, although it doesn’t look the best, is a fan mounted in the bathroom window. And even through it’s the simplest, cutting a round hole of the right size in a bathroom window is not a task for the faint-hearted. However, with care and precision it is possible.

Wall-mounted extractor fan

The second type is similar but wall-mounted, meaning you have to knock a hole in the wall instead. A lot more work than the window, but at least if you muck it up you can cover up the damage with cement and filler depending on whether you muck up the inside or outside.

Both these types have the fan and motor combined in one unit inside the bathroom and as such the electrical problems are compounded. The 17th edition of the relevant regulations stated that a bathroom or shower room is considered a ‘special location’. This makes fitment more difficult to do in a compliant way, making the job longer and therefore more expensive.

Inline fans

So the third type of extractor fan, if you can do it, is not only more efficient, but also easier for the electrician to connect up, and therefore cheaper. It’s called an inline fan and the only bit that needs to be put in the bathroom is a grille, usually in the ceiling.

From this a run of flexible ducting (like the outlet hose of a tumble dryer) is run through the ceiling void to the motor, mounted in the loft or roof space. On the other side of the fan a second run of flexible ducting takes the damp air to the outside world. This could be through a vent in the eaves or a special vented roof tile, although the former is much easier for a DIY job.

Set it all up with the electrician first

Whichever type you decide to install, have a word with your chosen electrician first. The fan you buy should have installation instructions but make sure your electrician is happy to share the work with you. Ask the electrician exactly where he wants everything to go and agree a date when you will have all the work done, so that they can come back and finish the job.

There’s nothing to stop you knocking the holes in the walls, eaves or windows, installing the fan and running the wires, but the electrician must connect the wires and test the whole installation before signing off the job.

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I have just replaced and upgraded an in line extractor fan to my bathroom. The old motor was wired using three wires, red, blue and yellow. The new motor only takes red and blue. I have taped off the yellow earth wire and fitted the. Red live and blue neutral. However than fan is running all the time. It is wired from a switch outside the bathroom so I thought it would only work by using the switch?
Phil - 20-Dec-16 @ 11:38 AM
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