In this article, we take a look at whether it is worthwhile to test extractor fans. Can you trust the manufacturer’s claims for your fan?  Is it important to test your extractor fan yourself?

Everyone understands the importance of good ventilation. In a previous article, we looked at how much ventilation is enough. But surely, once we’ve decided what size extractor fan we need, we can just buy one and trust the manufacturer’s flow rate claims? Well, not exactly. The flow rates that the manufacturer claims – the ones they put on the packaging – are calculated in a laboratory. There’s no ducting on the fans when they test them. There are no vents attached. They don’t extract up into your loft, under your floorboards and out through a roof vent. In short, they’re not realistic.

At PEATA, we’ve been testing a variety of fans under real-world conditions. We’ve tested them with ducting, with vents, and through cavity walls. The results may surprise you. Even adding a short piece of ducting and a gravity vent, like the one in the picture below, can reduce the airflow of a fan by more than 68%. Using a long snake of flexible ducting can reduce it even more. Even when you buy the duct, vent and fan as a kit from the same manufacturer they regularly fail airflow tests. But why?

It's important to test your extractor fans even if you've bought a kit like this

Ducts, bends, and vents all create turbulent flow and backpressure in your ventilation system. Extractor fans do not have high-power motors – they’re not Dyson’s! Many of them are cheap plastic mouldings with tiny motors, and they just don’t have the power required to move the air from your bathroom to the outside. The manufacturer’s know you probably won’t test your fan, so they can get away with these laboratory-condition claims.  That’s why it is important to test your extractor fans.

Every installation is different. A simple through-the-wall gravity vent is different to flexible ducting going up to a roof outlet. By using our videos to follow simple guidelines and best-practice and testing your extractor fan you can be sure you’ll have a healthy home.