Can I bypass timer on bathroom fan for humidistat instead?

Discussion in 'Electrics UK' started by Dan1976, 10 Nov 2014.

  1. Dan1976

    Dan1976

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    Hi All,

    I bought an Airflow AV125 fan (or at least I thought I did) but when I came to install it at the weekend I discovered its an AV125T fan (which has an integral timer).

    The problem is that I have also bought a humidistat to fit in the bathroom because we have a damp issue (mould stains on sloping ceiling) and I thought that would be the right way to go.

    I was just wondering whether anyone could advise if it was possible to wire the AV125T up so as to bypass the timer and control it by the humidistat instead?

    Advice greatly appreciated.

    Thanks.

    Dan.

     
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  3. ban-all-sheds

    ban-all-sheds

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    Stick with the timer one and learn to turn it on and off as required (you will - it is quite possible).

    But be prepared for it not to fix the problem if it's not simply a bit of local condensation from baths and showers which is to blame. You'll also need to get some proper mould remover to kill of the spores which are there.
     
  4. Taylortwocities

    Taylortwocities

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    Dan
    Please follow the guide if you are to post pictures
    http://www.diynot.com/forums/viewtopic.php?t=129539
    I cannot access your .img link.


    You can turn the timer fan into a non-timer by just connecting together the L & LT terminals. But I would recommend you use the fan in timer mode plus the humidistat as a second LT input.

    You might have been better to buy a fan that had timer & humidity controls already integrated.

    I guess you now have the humidistat? Is it a stand alone on? What make/model or do you have a pic of the installation diagram.
     
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  5. Dan1976

    Dan1976

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    Taylortwocities:

    Sorry about the pic - hopefully that's corrected now. javascript:emoticon(':oops:')

    I didn't want the timer function initially as I thought the humidistat option would be best.

    As things stand I've got the Airflow AV125T fan and the Airflow Electrical Humidistat (http://www.alertelectrical.com/prod/3934/airflow-electrical-humidistat-30-to-90).

    My thinking was that the timer and humidistat would conflict as means of control (ie. the timer might turn the fan off before the humidity has reuced?) but if there is a way of wiring the two together then I'd be grateful for the suggestion.

    Thanks for your assistance.
     
  6. Taylortwocities

    Taylortwocities

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    I cant see a wiring guide for that unit on the web. The Alert description says "for on/off operation of fans (3 ph. fans via contactor)"

    I would need to see the wiring diagram to see if you have even purchased the correct controller as you do not have a 3-phase fan nor a contactor.

    Normally you would wire the fan as per that drawing in your post but the switched live output from the humidity controller would connect to the LT terminal. Then the fan will come on when the humidity is too great. When the humidity reduces, the fan will run on for a while (re the timer)_.

    But I would want the fan to come on with the light as those humidity devices aren't so accurate (or effective). You would need a relay/contactor to do that as well as the humidity controller.
     
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  8. EFLImpudence

    EFLImpudence

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    Does it matter if the humidistat is back-fed when the light is on?
     
  9. Taylortwocities

    Taylortwocities

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    Probably not, but unless a relay is used, the humidistat will turn on the fan and the light when the humidity gets above trigger level.
     
  10. EFLImpudence

    EFLImpudence

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    D'oh, of course. :oops:

    I was not thinking of back-feed going the other way.
     
  11. JohnW2

    JohnW2

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    Indeed - and if a relay were not used (accepting that the humidistat would then turn on light as well as fan), I would have thought that there could possibly be 'back-feed problems' (from light to humidistat), such as suggested by EFLI, if (as is likely) the humidistat had a semiconductor (i.e. triac) 'switch', rather than a relay, to operate the fan.

    Kind Regards, John
     
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