Centrifugal fan for a bathroom

[dskeeles]

Hi,

We're currently having a shower put into our 2.2x2.5m bathroom, and I understand we need to upgrade the extractor fan. Currently we have a ceiling-mounted centrifugal model, which has solid plastic ducting that takes it up from the bathroom false ceiling, and then lengfhways through around 4-5m to an exterior wall.

I've worked out that 20x the volume of the bathroom, as recommended when there's a shower fitted, would need 180m^2/hr flow rate. Also, that it'd have to be a centrifugal to force the air along the 5m duct.

Trouble is - they're quite hard to find. I've come close (Manrose Pro Showerlite Centrifugal Chrome 35W Shower Fan Kit on Screwfix), but these require the fan itself to be fitted inside the ceiiing. Do-able, but expensive.

Can anyone suggest any other suitable fans? Do I really need a 20x flow rate, and will an axial fan do?

Thanks!

Damian

[BigWallop]

Leave the original in place and search for an inline extractor to supplement the push through the longish run of ducting. Like one of these

installed into the center of the duct in the loft. This solution keeps the existing fan to push the moist air into the duct and uses the second fan to drag and push it through the final part of the vent. It's a technique used on many industrial extraction systems, to keep the weight and noise to a minimum. Many smaller fans just keep the air moving through the system, instead of one big fan doing all the work and creating noise and being bulky.

Simple installation that minimises damage to surrounding decoration in the bathroom. Connects in to the existing wiring scheme. I've also seen them connected individually for use on different situations in bathrooms with loos. The inline extractor is used for just air change when there are smellies, and both fans used when the room is filling with moist air.

There are many to choose from, so have a search for yourself. You may even find a better solution to match the new decor' you are going to have.

Have fun, and good luck with it.

[dskeeles]

these

installed

Thanks - I did see one that had a solo inline fan - it is appealing, but the trouble is we're in a flat, and the ducting is boxed and painted in along the top corner of the corridor and kitchen. Hence there's no space for a fan, along with a fair bit of drama in keeping it tidy and getting power to it.

Half of this DIY malarkey involves wishing for an alternative house to build it into.... :-(

[BigWallop]

these

> into the center of the duct in the loft. This solution keeps the existing

The size of these inline extractors is suitable for inside the boxing. Remove one face board outside the bathroom and fit the fan. Pull the cable over to the fan in the bathroom and connect it in.

These fans are meant to fit inside a 110 mm pipe.

[dskeeles]

Thanks!

I had a look, and thought I might be able to place one just inside the kitchen, around 2m along the duct, and feed the power cable down the duct to the grille.

However - my wife regards it as 'scope creep', so I've had to continue with a 'bolt-on' solution for now. I've ended up choosing an XpelAir DX200

- on the basis that we can just replace the old fan with it, maybe even recess it in the ceiling space without having to open it up entirely, and then play with the speed and timer adjustments until we find the right combination of noise, duration and extraction rate. Even this is only rated for 107m3/hr, against my 180 requirement, but I suspect from the scarcity of high-flow fans that this isn't always followed. Even if the room over-steams up during a shower, we can set the timer to run a bit longer to make up for the low rate.

Also - if this proves not to be enough, then I could always add the inline fan as well later on - and the two together should permit a quieter flow setting on the first.

An in-duct fan would be a nicer engineering decision, but a less comfortable decorating one in this case....

D