These are the main points to consider when buying a bathroom fan:
Air Movement or Extraction Rate
This describes how much air (steam) is moved from the bathroom over a certain time period and is quoted in either metres cubed per hour (m3/hr) or Litres per second (L/s). Some websites quote m3/hr while others use L/s, making it hard to compare performance between fans. At Bathroom Fan Shop, we quote both figures.
The UK Building Regulations Part F state that bathrooms require at least 54m3/hr air change. In practice an extraction rate this low would take a very long time to shift the steam from the average UK bathroom and as a consequence manufacturers' extractor fans are considerably more powerful. As a rough guide, these days, entry level fans start at around 80m3/hr, but we would recommend looking at nothing less than 90m3/hr. A number of models at Bathroom Fan Shop satisfy this including the Envirovent SIL100 and Silent Tornado axial fan ranges and all of the inline fans.
How Long is Your Duct Run?
As the actress said to the Bishop, it's as much about the blow as the suck. Extractor fans have to 'exhaust' the air they are extracting. Every inch of ducting adds extra air pressure against which the fan has to fight. As a rough guide, axial fans should not be ducted more than four metres, (although the Silent Tornado will handle longer duct runs up to 10m), and inline fans should not be ducted more than 6m.
As a rule of thumb axial fans are mounted on and thus ducted straight through the wall. If you are ducting an axial fan through the ceiling, then you may have room, (and we would recommend) using an inline fan which can duct further. Remember to keep your duct run as straight as possible. Every bend and kink adds air pressure, which you want to avoid.
Nearly all fan ranges come in a number of models and may be operated or controlled using the following switching methods:
- Basic: No integral switching. The extractor fan is wired into a remote switch like a pullcord or the lighting circuit.
- Pull Cord: ..Fairly obviously, these come with integral pull cord. They're not as popular as they were a few years ago and most manufacturers don;t make a pull cord version.
- Timer: This is an over-run timer which keeps the fan running after you have manually turned it off. This feature ensures that all steam is cleared from the bathroom and is always the most popular model in all ranges.
- Humidistat: This switching option turns the fan on automatically when humidity reaches a pre-set level in the bathroom. This is a very useful feature for bathrooms which also house the toilet, for bathrooms with lots of natural light and tenanted properties.
- PIR: This stands for 'Passive Infra Red' and means that it has an integral Occupancy Sensor. ..In other words, it will switch the fan automatically when somebody enters the room.
Please note, particularly if replacing a fan: Basic and Pull Cord fans require two core and earth cable, whilst Timer, Humidistat and PIR fans require 'three core and earth' cable, which has both 'switch live' and 'permanent live' wires. If you are replacing a basic or pull cord fan with a timer fan, for example, your electrician may well have to replace the cabling too. - Not difficult, but something you should keep in mind.
This is not such an issue as it used to be as so many fans these days are made to run quietly at around 25/26dB(A). Bathroom Fan Shop stocks a number of ranges which are quiet or silent: The Tornado, Envirovent 100 and Airflow Quiet Air are the most popular.