Testing extractors fans – is it important?

Testing extractor fans – is it important?

The legal requirement to build more highly insulated and air tight buildings to meet stringent Building Regulations means that it is increasingly more important to ensure buildings are not only adequately ventilated, but that the ventilation system is installed correctly, works efficiently and meets the required levels of operation.

To maintain this standard all mechanical ventilation systems (including intermittent extractor fans, such as those installed in kitchens and bathrooms), need to have their flow rates tested under Part F of the Building Regulations.

The results are submitted to building control as part of the overall building compliance process so obtaining the official approvals is crucial in any development.

Do you need an extractor fan?

In the past, ventilation came from natural sources – in older homes an open chimney, sash windows and gaps between the floor boards all allowed air to enter and leave the dwelling. Moving forward controlled methods of ventilation were introduced such as fans and window trickle vents in addition to the invisible but significant uncontrolled quantities of air infiltrating into the dwelling through the building fabric.

But now with stringent regulations on the air tightness of new developments and the increased focus on minimising energy losses from buildings, especially due to infiltration, suitable and effective controlled ventilation techniques must be included in all new dwellings.

How are they tested?

Regulation 42 of the Building Regulations 2010 requires developers to provide evidence of the testing of all fans to the Building Control Body (BCB) within 5 days of the test being carried out.

The Domestic Ventilation Compliance Guide (DVCG) published in 2010 by the government gives the full approved procedures for measuring air flows and reporting.

What problems can cause test failure?

In order for an extractor fan to pass the test it needs to be working to its full capacity and extracting at its full rated air flow. When installing in new developments there are some simple pointers to follow:

Install the right extraction fan for the job: Different rooms require different flow rates, for example a toilet will require a lower level of extraction than a kitchen. It is best to install the fans that exceed the minimum flow rate levels required for that area.

Install the right type of duct: Unless the fan blows the air directly into outside open space, a duct is required to channel the air away from the extractor unit and room. Selecting the right type of duct is important. It should be:

  • As rigid as possible – flexible ducts can restrict the airflow rate and can be easily damaged

  • Not too long – the longer the duct is, the lower the performance of the air extraction

  • Minimal turns or bends – the duct should be as direct as possible to maintain maximum airflow 

No obstruction to the external outlets: where the duct finally releases the air extraction must be kept clear

Passing the extraction fan test

At Energytest we have a team of experienced test engineers for both commercial and domestic developments. Our engineers can help you comply with Building Regulations and can provide you with valid certificates within 24 hours of inspection.

All our test equipment is UKAS calibrated and our consultants can continue to be on hand throughout the construction process offering free advice and guidance. Have a look at our website for a comprehensive guide to complying with Building Regulations.