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Here's a conundrum - Why has my extraction system gone haywire?

Discussion in 'Electrics UK' started by Drizzlelive100, 25 Nov 2015.

  1. Drizzlelive100


    17 Dec 2012
    Thanks Received:
    United Kingdom
    Good morning,

    I wonder if someone would be kind enough to give me some guidance on this problem.

    I'm utterly clueless about these sorts of things, so thought I'd see if any kind experts could help.

    So I am in a new build top floor flat. It's rented and the landlord owns dozens, so doesn't really know much about how the flat 'works'. On the ceiling in each room are circular extraction fan outlets (I presume). There are ones in the kitchen, living room, toilet, and bedroom.

    There are switches for the ones in the kitchen and the toilet. There are not, from what I can see, switches for the living room and the bedroom.

    In a cupboard there are three unidentified switches.

    1. Is a switch that looks like a standard light switch, that seems to cause a whirring sound -which I assume is linked to the extractor unit.

    2. Is an isolation switch which used to turn the whole unit on and off. I rarely touch that, because when I did in the past (eg going on holiday), I would come back and have a nightmare trying to get my bathroom extractor fan to start working again, only flicking switches in random orders, waiting for things to die down etc would finally get my bathroom extractor fan working.

    3. A third "standard light switch" style switch - situated at the very top of the cupboard, which may or may not have something to do with the extractor fan.

    Everything was working fine - I think the isolation switch was ON and I could use the switches in the kitchen and the bathroom to turn on my extractor when I was having a bath, or cooking etc. Perfect.

    Then there was a momentary power cut two nights ago. And everything has changed. My kitchen and bathroom ones stopped working and bizarrely my bedroom and living room units have started making a right racket and started extracting air.

    This is hugely irritating and I can't for the life of me work out how to reverse this - or what combination of switches I should be pressing to try and make this stop! So I have sleepless nights, as it's like being in a hotel room with noisy air conditioning. Remember, there are no switches in the bedroom and the living room. If I try and turn off the whole unit (not sure how I do this - just turning a combination of the cupboard switches to off), I still have a fairly noisy (but not as noisy) experience in the bedroom. As if it's on standby or something. This never used to happen.

    I know nothing at all about electronics, or extractor fan set ups in flats - so I feel if in doubt you should ask people who enjoy DIY and see if anyone is kind enough to suggest what might have happened and how I can solve the problem without bothering the landlord.

    Should the isolation switch be on or off? What combination of switch presses should I use to try and reset it? Should I try and turn all of my electrics off to hope I get a reversal during another power cut.

    I will try flicking different switches in different combinations in a day or two - you often have to wait a few minutes for the extractor unit to die down, it also then seems to whirr back up again to a sort of "standby" quieter sound - and I find that you sometimes can get the bathroom fan working again (post, say a holiday), by waiting a few minutes and then trying turning the fan on from the bathroom switch.

    I can't see the extractor unit and assume it's hidden away in the loft - which I can not access.

    But you can hear it!

    Many thanks in advance for any one who can help. I hope I have given enough detail despite my complete lack of knowledge on this. There are no instruction manuals here either, but maybe there is a simple answer!
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  3. stem


    20 Jul 2005
    Thanks Received:
    United Kingdom
    It's difficult, because we would need to know what the switches are connected to. I suspect that you may have a central trickle ventilation system operated from a central point ventilating the living and sleeping rooms. The kitchen and bathroom probably have separate controls as a boost for when you are cooking, or having a....err......bath.

    The ducts may be linked to a HRV (Heat Revovery & Ventilation) system, whereby the extracted air passing through a heat exchanger before going outside. Fresh air then comes in from outside, passes through the same heat exchanger and picks up some of the heat from the outgoing air before it comes back into the property. If so, the air streams are completely separate and there will be two fans. One drawing air in and one drawing air out. They are usually housed inside the heat exchanger and controlled from one central point.

    But without knowing what mechanical equipment is installed, it would be impossible to guess. so I would suggest that you either find out from the landlord, or ask around some of your neighbours, it's likely someone will know how it works, otherwise some photos of the switches and outlets may help someone identify what you have.
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