Broken bathroom extractor fan

dl8860

dl8860

dl8860

Soldato
Joined
25 Jul 2010
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Worcestershire
Extractor fan in the bathroom of my flat has been broken since I moved in and its about time I got round to fixing it.

Landlord lives miles away and has agreed I can arrange for a handyman to come and sort at at his expensed, but as both my partner and I work full time I've not managed to get this sorted.

So I thought I'd have a crack myself, how hard can it be
It's definitely my first time doing stuff like this though.

First things first, it's a 12V 100 manrose fan, pretty old and blocked up so not surprised it's broken.

Suitable looking new fans all seem to be 240V and a bit over 100m. I've taken the cover off and measured the width of the extraction hole and it is only a shade over 100m.

I like the look of this one

http://m.screwfix.com/description.htm?id=15927

But like I said above it's 240v and says hole diameter of 112mm. All others I can find seem to be similar. Am I misreading what these mean? Or can someone spec a suitable fan? Cheers!
 
You need a 12V fan. These are low voltage - and therefor safer than 240V

Legally you can only use 12v ones on zone 1. The power feed will also be 12v with the transformer being in the loft that will step down from 240 to 12v

Got a pic or model number ? Should be easy to just replace. The power will be off the lighting circuit so isolate that at the consumer unit to swap over
 
Right ok, it is in Zone 1 as it's within confines of the shower.

So I can just switch out the current 12V one with a new 12V one and the transformer will continue to do the job?

Don't have a model number but it's a Manrose so I'll get similar to replace.
This looks legit
 
So I've got round to wiring up the new fan but alas it's not running.

Went and bought a multimeter today to test the wiring to see if it is in fact live.

There is a transformer above the door which has a light on, so my initial assumption is that this is live and so there should be power to the wiring into the fan

transformer.jpg


However, like I say the fan is not running but it's a brand new unit and the same model as the previous one, so I still suspect the wiring.

This is the fan

bathroomfan1.jpg


So what I've tried is to test the red (live) and blue (neutral) wires using a multimeter

bathroomfan2.jpg


just placing these onto the exposed bit of wire to try and get a reading

multi.jpg


Now I'm not getting a reading at all, not even a nibble. This is with the range at 200V AC. As the supply is supposed to be 12V, this should still register shouldn't it?

I've tried the multimeter with an AA battery and got a reliable reading so I know it's working.

So possible scenarios:

1. There is no voltage in the wiring between the transformer and the wires which go into the fan

2. There is voltage in the wiring and somehow neither the new fan or my attempts with the multimeter can detect anything

So it would seem to me that most likely situation is numero 1 and that some rewiring is going to have to be done, which would call for an electrician?

Bear in mind it's a rented property (so really I should have just got a handyman in from the start, but I thought it was the sort of job I should be able to sort myself and wanted to do it and learn)

Thoughts appreciated (including any obvious things I might have missed!), thanks
 
Bump. Also have checked the transformer and plug next to it for blown fuses but there's no fuse in either.
 
possible that the transformer is turning the voltage into DC, flick your meter to the 200v on the left hand side instead of right and check again

any stickers or lables on the fan ?
 
You're using AC setting by the looks of it? The 12V is likely to be DC. Check but I think that would be a factor..

I have two meters - one clearly labels AC and DC on the selector whilst the other show it as a wavy and straight line.

Just start with the 600V AC on the connection then if there's no reading, switch to 200V AC.. still nothing then switch to 12V DC such as 20V DC setting..

Try a 9V battery with the meter set to DC first..

Just don't use the 10A probe socket (left) - stick with the other one (right). If you do.. what will happen is that it will allow 10A of current at 230V through.. I did this and the consumer unit tripped. the probe points are slightly blunted due to the arcing.

Actually an electrician's screwdriver is great. The neon lights up.. faster for detecting 230V 'is it on' than having to setup the meter..
 
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No my probes are in the right holes, and both previous and existing fan are AC so not expecting that to be a problem. I did measure for AC and DC and no reading on each.

The existing one has not been working since I've moved in but I'm pretty sure it was operational at one stage, was all full of Crap and blocked up when I took it out.

I guess the only thing I can do now is take a reading directly before and after the transformer?
 
If your happy to do this then I would do as you mentioned, check the output direct form the transformer and double check the mains voltage to the transformer
 
I can't see the pictures as I'm at work, but if there's an output limit on the transformer then it might not be enough to power your new fan.

As you say, taking an IP and OP reading on the transformer is the next step in isolating the issue.
 
Evening subscribers.

So, voltage reading taken either side of the transformer and I got a nice 240V on the way in and a fat zero on the way out. So it appears to me I'll need a new transformer unit.

Inside of the transformer looks like this

transformer_1.jpg


Points I measured from out of the transformer were these

tfout.jpg


which registered nothing and were a pain in the butt getting back into the junction box.


What I have to hope for now is, if I buy a new transformer will it fit with the fixing of the old one attached to the wall.

tffixture.jpg


This wasn't the case with the fan despite buying the same model (i.e. the screw holes didn't line up so I needed to drill and put new wall plugs in) as I think the existing one was an older version. So I'm not hugely confident it will, if not just adds to the size of the job I suppose. This is turning into a DIY log...
 
New transformer works a treat, plugged it in tonight. Spot of drilling to fix the fan in and job done!
 
Simon said:
You need a 12V fan. These are low voltage - and therefor safer than 240V

Legally you can only use 12v ones on zone 1. The power feed will also be 12v with the transformer being in the loft that will step down from 240 to 12v
Click to expand...

Nope, 230v fans are acceptable for zone 1 provided it is IPX4 rated and connected to an RCD.

Glad you got it sorted though OP! Sounded like it was a breeze.
 
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