Testing Installed Performance of Ventilation Systems
Q Since when do I have to test the ventilation I have installed?
A Notifiable works for new and existing buildings planned to comply with the new 2010 Building Regulations, effective October 6th 2010, are subject to a new Domestic Ventilation Compliance Guide which introduces a requirement for air flow testing, commissioning and information provision. There are now specific statutory requirements to "commission mechanical ventilation systems" (where they can be tested and adjusted) in accordance with an approved procedure and provide a notice to the Building Control Body (BCB)
Visit: www.planningportal.gov.uk/approveddocuments>partFventilation>associateddocumentsto download a copy of the guide which explains in detail what measures should be taken to submit information to BCB.
Q Does everything have to be tested?
A Yes, from a basic extract fan in the toilet to the supply and extract valves in mechanical ventilation with heat recovery system.
Q Can I measure the air flow of a fan from the inside?
A No. Each product is designed differently with a variety of entry slots in the grille. Using an Aircone to cover the front grille will cause disruption to flow and blockage of products with side entry slots.
In any case, the purpose of the test is to establish the air flow at the point of discharge.
Q The outlet of the system is four floors up.
A The wording in the Domestic Ventilation Compliance Guide does state systems should be measured "where they can be tested and adjusted".
Always follow Health and Safety guidelines such as the "Work at Height Regulations" Contact the BCB for further guidance
Q The readings at the grille are lower than I expected, what could be the cause?
A This could be due to one or a combination of factors, for example.
a) Is the correct type of fan being used in the specific installation i.e. Axial for through the wall
and short duct runs as specified in the Domestic Ventilation Compliance Guide. Longer ducts and
flexible ducting not pulled taught will cause additional pressure drop and reduce flow.
Centrifugal and mixed flow fans for longer duct runs not exceeding the design recommendations in the Domestic Ventilation Compliance Guide.
Note: The new guidance requires an extract grille to have a free area of not less than 90% of the extract duct area. Grilles of a lower free area will reduce air flow by blocking the exit
b) Using the Anemometer
Is the rotating vane sensor pointing into the air flow? Facing the wrong direction will affect the reading.
Is the measuring instrument in good condition with the vanes spinning freely and do you have a valid certificate of calibration dated within one year?
Have you entered the area factor into the meter to be used with the Aircone? This factor calculates the blockage effect of the hood when used with the meter. The incorrect area factor will render volume flow readings from the instrument incorrect. Refer to the user manual. Refer to the calibration curve supplied with the instrument for further corrections.
What were the prevailing conditions of the day? Changes in temperature, humidity can affect readings. Also consider the effect of wind blowing onto the grille during the test. A calmer day would provide better results.
Q What do I do with the readings?
A Test results should be notified to Building Control within 5 days.
Visit www.planningportal.gov.uk/approveddocuments>partFventilation>associateddocuments to download the Domestic Ventilation Compliance Guide which includes a copy of the approved test results form that can be submitted to the Building Control Body.
*Indicates a required field.