What's the point if it isn't doing it's job? - Greenwood


16 November 2013

What's the point if it isn't doing it's job?

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You might see a bathroom fan and hear it, but how do you know its doing the job its supposed to?

We expect the products we buy to perform. For instance, we expect our fridge to keep our food cool and fresh; we expect our washing machine to wash our clothes; we expect our phones to be able to make calls, send and receive emails, and more…Ventilation is no different.

Performance should be achieved, even guaranteed, and should be the number one priority.

We’d be quick to tell the manufacturer if our fridge wasn’t cold or if our clothes came out dirty. Appliances may look nice, run quietly  and are energy efficient but if they're not doing the job correctly, then what's the point?

With ventilation you should expect the extraction of air and moisture from your bathroom, kitchen or, in the event of a central system, your house. The thing with ventilation is that it is sometimes too late before you realise that, even though you can see it and hear it (sometimes you hear too much), it isn’t actually doing the job it’s supposed to – cue mould and condensation! Conversely, you could also be experiencing too high a level of extraction and have a continuously cold bathroom and rising energy bills!!

But why does this happen?

There could be several factors but we have come to the conclusion over years of working in ventilation that there are three fundamental reasons:

1. It’s the wrong product for the job

Did you know that where and how you install a typical bathroom fan impacts on its performance?

You can put a fan in a wall, in a ceiling with ducting and even in the window, but do we really know about how much resistance these applications make to its installed performance?

We did a bit of a test with seven typical bathroom fans – to a British Standard no less (BS EN 13141) and we found that;

  • Some fans were over ventilating and some were under ventilating;

  • The fans that were over ventilating were doing so by 53% in ducted applications and by 42.5% in through wall applications;
  • The fans that were under ventilating were doing so by 33% in ducted applications and by 37.5% in through wall applications.

The thing is, not doing enough will be detrimental to the building with mould, condensation and poor indoor air quality… and doing too much will be detrimental to the occupant with nuisance running, heat loss and higher energy costs. It really is a fine balancing act.

With intermittent ventilation particularly, it is fundamental that it is performing because it may only be on for 45 minutes to 1.5 hours a day – not long when you think about a family cooking, showering, breathing and drying clothes indoors!!!

Even with automatic sensing, such as humidity, the level of ventilation will be increased whenever high humidity levels are detected. If this is the case then ventilation performance at the correct level will be crucial because there is a need!

With axial, mixed flow and centrifugal options offering varying levels of performance and pressure handling, it still leaves us in the dilemma of not knowing whether it is actually going to do exactly what it’s supposed to once it’s installed>

2. It can’t be adjusted

With typical intermittent ventilation fans for bathrooms, kitchens, WCs, and more, there is usually one setting which is aligned with the Building Regulation requirements. For bathrooms, as an example, the fan should achieve 15 l/s when installed.

What we have to question then is - is it really achievable in the actual application in which it’s going to be installed because ducting three metres or more will impact airflow performance more than a wall? Usually performance levels are increased to compensate for installation, however we have seen through our own testing that this is either too much or too little.

If we could adjust the airflow at the point of installation, or set it to suit an installation, then we would be getting closer to achieving GIP and the airflow rates set out in the Building Regulations.

3. It’s been installed incorrectly or not even set up

A poor installation or incorrect set-up (or even no set-up at all) will impact how the fan is performing. If the ducting is crushed it will not extract and it will cause noise. If it’s been set on WC flow for a bathroom it won’t perform effectively because it’s running at a lower rate than required.

If the humidity sensor is turned down, the fan will come on all the time – way more than needed! If the humidity sensor is turned up it will rarely or never come on (because it will be looking for 95% relative humidity levels!!!) – something we are familiar with and have been called to site to review!

Installers play a part in achieving GIP Guaranteed Installed Performance and training and understanding is essential to ensure the right things are done on site!

If we could choose adjustable and easy to set-up and commission products that would ensure that those fans are working effectively from the very moment they are installed, then again we would be closer to achieving GIP.

Choosing performance will reap rewards for the home and the occupant

Above everything else, GIP or Guaranteed Installed Performance should be at the top of the agenda because when you know the product can perform you have peace of mind that it’s doing the job it’s supposed to and you are eliminating risk of future, costly issues.

There are many extractor fans that have been around for years and its not to say that they don’t work. We are in a world where technology moves on, Building Regulations move on and, if the ability to choose a product that you know will perform then you can easily achieve GIP, why not choose it? Our buildings are getting more airtight thanks to insulation and double glazing so we need to allow the air and moisture to escape effectively.

With five million homes in the UK suffering from mould and condensation, let’s put performance first. Lets choose the right solutions to achieve GIP that can be adjusted to suit the needs of each individual installation easily - after all You wouldn’t choose Ussain Bolt to run in the 5000 metres or ask Wayne Rooney to bat for England in the cricket would you???


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