How to measure a replacement bathroom fan?

[Shane]

Hello,

I need to organise an electrician to replace our non-functioning bathroom fan. It's a wired-in model on the wall that vents directly outside.

How do I measure our cut-out? Is there a replacement model you can recommend so that I have something the electrician can install (and only have one call-out fee?)

The grille on the fan is 300mm wide but without the grille the fan is 270mm.

Photos below.

Thanks heaps.

[EricL]

Hello @Shane 

Thanks for sharing your question about replacing your bathroom fan. The 270mm measurement is the flange of the fan that is technically where the screws are placed to hold the fan in place. The actual cut out out space is the interior space after the flange. I've placed an image below with a yellow arrow indicating what the cutout is plus the thickness of the plastic. 

It is critical that when you purchase your new fan that you read the manual and get the actual wall cut out specifications. It will be counterproductive if you get a 300mm wide fan with a cutout at 290mm, this means that you would have to make the hole bigger instead of having an easy to install piece.

Just a friendly reminder that any electrical work will need to be accomplished by a licensed electrician for safety and compliance.   

If you have any other questions we can help with, please let us know.

Eric

[Shane]

OK, thank you. So we should get a 210mm fan? Can you please recommend one? 

[EricL]

Hi @Shane 

Most of the modern wall exhaust fans are now smaller due to their high efficiency motors. Back then the fans needed to be big in order to move a large volume of air, but these new fans are half the size and are capable of moving the same amount of air and more. I suggest looking at the Blauberg 150mm White AUTO Wall / Ceiling Exhaust Fan With Automatic Shutters. It has excellent reviews and is capable of moving 295 cubic meters/hr.

You can technically keep the exhaust hole on the exterior wall the same, but the interior wall will need to be plastered, and a new hole cut for the smaller exhaust fan.

If you need further assistance, please let us know.

Eric

[Shane]

Thanks. I was trying to avoid two seperate electrician call-outs as our place is remote. 

With a smaller fan we would need to get an electrician to uninstall it, then get them back again later after we had repaired the plasterboard. 

Any other ideas? 

Perhaps a bigger fan would be better as the electrician could probably cut a bigger hole... Can you recommend a bigger fan?

[MitchellMc]

Hi @Shane,

You have a ceiling exhaust fan mounted on your wall. Please be advised that these are ceiling fans and have not been designed to run on a vertical surface. Due to the bearing assembly, you will see a shortened lifespan since it is not ceiling-mounted. You should check with your electrician whether this installation orientation is acceptable. If not, you'd need to go with a purpose-built wall exhaust fan and adjust the hole as per @EricL's guidance.

Exhaust fans are referenced by the size of their blades, so an Arlec 200mm White Fan Exhaust has 200mm blades. For this model, a 240mm diameter cutout is used. If your cutout is around 240mm, this Arlec fan should be a direct replacement. There's a bit of leeway as the edge of the frame overhangs the plasterboard. 

You'd need to measure the cutout precisely to guarantee it will fit without adjustment. You can see the cutout is slightly larger than the frame through the hole on the right below your tape measure.

For a larger fan with a larger cutout, you'd simply move up to a 250mm fan.

Please let me know if you have any questions.

Mitchell

[Shane]

Sorry, I'm a little confused now. 

Does Bunnings have any fans that are suitable for a wall rather than a ceiling? 

And what you are saying about the size seems to be different to what Eric said above. If you look at my first photo, what size fan do you think I currently have?

[MitchellMc]

Hi @Shane,

We have plenty of fans designed as wall exhaust fans, but not in that style or that would suit the current cutout.

I suspect you have a 200mm ceiling exhaust fan as your blades appear to be around 200mm across them. Ceiling fans typically come in 200 and 250mm.

Mitchell

[Shane]

Thanks for your advice. I've contacted an electrician and they are just going to replace it like-for-like.