Good ventilation is important for the whole house but is vital in areas that create more moisture, such as kitchens and bathrooms. Without proper ventilation, bathrooms can be prone to condensation, damp, and black mould. If not dealt with, persistent moisture in the bathroom could spread, leading to damp in other areas of the house.
A mechanical extractor fan can be a good way to remove moist air from the bathroom, but it is important to choose the right one.
A bathroom extractor fan isn’t a luxury – it’s a must. As well as sucking away any unpleasant odours, it removes moisture from the air after a shower or bath, which can otherwise lead to long-term damage, especially if your bathroom doesn’t have an outside window. And if you plan on letting out your property, an extractor fan is a legal requirement.
Most domestic extractors pull through about 21 litres of air per second – which is plenty for an average-sized bathroom or shower room. To ensure the room gets fully ventilated, it’s a good idea to look for a model with an over-run timer, which keeps the fan running for a set period after you’ve turned it off.
The precise duration of the over-run is normally configured during installation, with most fans offering a range between 30 seconds and 30 minutes. You might as well tend towards the latter end of the scale, since the cost is very low: on average a fan like this uses around eight watts.
Most fans also come with a back-draught shutter to prevent cold air from blowing in from outside. The downside to these is that windy conditions can cause the shutter to clatter against the wall; if your outlet is exposed to the elements it may be better to simply leave the shutter off.
Finally, if you think you (or anyone else in the house) will forget to turn the fan on, consider a model with a humidity sensor. This automatically activates the fan when the level of moisture in the air exceeds a certain threshold. This sensor may need occasional cleaning, though, or the accumulation of dust or grime will hinder its effectiveness.
The most important things to consider when purchasing an extractor fan:
Because electricity and water do not mix well, the UK has regulations restricting what types of electrical equipment – such as lighting, plug sockets, and extractor fans – can be installed in which areas of the bathroom.
The bathroom is divided into different zones. Zone 0 is inside the bath or shower, zone 1 is the area above the bath or shower (to a height of 2.25m). Zone 2 is the area continuing 0.6m horizontally away from the bath or shower. Anywhere beyond 'this, is classed as outside the zones'.
Devices have an IP Rating, which rates their resistance, or that of their enclosure, to penetration by solids and liquids. The first digit of the rating relates to solids and the second relates to liquids. Fans in Zones 0, 1, and 2 need high IP Ratings for liquids.
There are several options when it comes to operating your fan. You can turn it on manually, using a cord switch, which is often the same cord as the light switch, or by remote control. Some fans have timers, turning them off a set time after the lights.
PIR (Passive Infrared Sensors) operate when someone enters the room, and fans with humidity sensors turn on and off when the humidity or moisture in the air hits, and then returns to, a certain level.
It may not be the first thing you think of, and you might not appreciate it unless able to see the unit running, but some extractor fans can be noisy. This can be an issue, especially if loud enough to disturb neighbours, if you have children and tend to bathe or shower after their bedtimes, or if you are susceptible to noise yourself. There are, however, many low-noise models available, and manufacturers provide a decibel level, to give an idea of how noisy they are even if you can’t see a demonstration of the model.
As with the noise issue, this might not be your first consideration – but your extractor fan is likely to stay in place for a long time, so you ideally need to appreciate its look and design.
The air extraction rate is measured in 'Litres per Second' (l/s) or 'Metres Cubed per Hour' (m³/hr). This is the rate at which the extractor fan removes air when operational and is one of the most vital factors. Building regulations say that a fan must extract no less than 15L/s in a standard domestic bathroom, so most models will cover this. Large or well-used bathrooms might need higher extraction rates.
As well as the fan, you will have a choice of fixed or gravity grilles, which are exterior grilles covering the vent through which the extracted air is expelled. Gravity grilles tend to have slats that are pushed open by the extraction process and then close under gravity. This prevents backdrafts when not in use but can be noisier, especially if they are located beneath a bedroom window. Fixed grilles can be quieter but might let in air through the slots.
Heat recovery is usually an option for whole-house ventilation systems, where stale air is extracted from areas such as bathrooms, kitchens, and utility rooms, and passed through a heat exchange. Fresh air is simultaneously brought in from outside, filtered, and passed through the exchange, recycling much of the heat. Some innovative single-room heat recovery (SRHRV) systems, however, can do the same thing through a single unit.
When choosing a bathroom extractor fan consider these options, so your house remains well-ventilated, helping avoid the damages of moisture accumulation.
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