Cloakroom Extractor Fan

TicTax · Jan 12, 2019

Hi All,

I'm installing a new extractor fan in my downstairs loo. The wall that the fan will be mounted to backs on to my garage and the ducting runs in to there before turning 90 degrees and exiting through the roof. This is a ducting run of around 4m.

Given that the downstairs loo is just that and doesn't contain a shower, it'll never be humid. Therefore, with a ducting run that long, can I install an axial fan or does it have to be centrifugal? I'd prefer axial because frankly they're less of an eye-sore.

Thanks in advance for any and all help,
Robin.

Bellendian · Jan 12, 2019

Building regs don't specify extraction for a wc alone, so I'd suggest that you can do what you like. If you want it to be effective then try to use rigid ducting rather than flexi as it results in lower losses since it's smooth.

pirate · Jan 12, 2019

I had exactly this problem when my new cloakroom was installed. Builder said I must have a fan, and it is internal, no window. he installed the cheapest, flush fitting fan, and the ducting runs down the cavity wall, under the house and basement, to an outlet on the gable end, in all about 10 metres. Result? The fan extracted the air until the fan stopped running, and the compressed air simply returned through the grille, no use whatsoever...yer far*s just came back!
I fitted a centrifugal fan, and it does the job very well. It has back-draught shutters, too. Ok, it sticks out from the wall a bit, but it would be possible to recess it. Next time, as I have a nice cavity to work with (ooh, missus!) I will install an inline fan behind the wall, or in the ceiling cavity. BTW, just a Manrose centrifugal fan from screwfix, not expensive, and 15 years on I replaced it last month for exactly the same model.