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Author: Subject: Reversing a 240v extractor fan?
Nickp

posted on 23/11/12 at 07:57 PM Reply With Quote
Reversing a 240v extractor fan?

I've been given a nice big Vent-Axia extractor fan to put in the back wall of my garage extension. Just stuck a plug on it and it's blowing the wrong way, so the electrical gubbins would be on the outside of the wall and exposed to the elements. The rear of the motor has 4 terminals with only 3 in use (L,N,E). L is currently connected to A0 and A1 is spare. Is it as simple as swapping the live over to A1 to get it spinning the other way? Or am I about to blow the thing apart in spectacular fashion??




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daniel mason

posted on 23/11/12 at 08:04 PM Reply With Quote
think yove got a window fan. can you fit it on the outside wall instead?






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steve m

posted on 23/11/12 at 08:08 PM Reply With Quote
turn the fan round the other way ?
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Nickp

posted on 23/11/12 at 08:10 PM Reply With Quote
quote:
Originally posted by steve m
turn the fan round the other way ?


First thing I thought of but unfortunately it won't

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big-vee-twin

posted on 23/11/12 at 08:33 PM Reply With Quote
Can you get the fan blades off the motor and mount it on the other way round





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Nickp

posted on 23/11/12 at 08:36 PM Reply With Quote
quote:
Originally posted by big-vee-twin
Can you get the fan blades off the motor and mount it on the other way round


Unfortunately not. The only options are to get it spinning the other way or get another one.

[Edited on 23/11/12 by Nickp]

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owelly

posted on 23/11/12 at 08:53 PM Reply With Quote
Disconnect the live and see if there's continuity through the spare terminal. If there is, connect your live to it via a piece of 2amp fuse wire. See what occurs!





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Nickp

posted on 23/11/12 at 09:25 PM Reply With Quote
quote:
Originally posted by owelly
Disconnect the live and see if there's continuity through the spare terminal. If there is, connect your live to it via a piece of 2amp fuse wire. See what occurs!


Will do, you may hear the bang in Whitby

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I predict a Riot

posted on 23/11/12 at 09:42 PM Reply With Quote
It is more than likely a shaded pole type motor and therefore designed to only run one way.

Sorry





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Nickp

posted on 23/11/12 at 09:44 PM Reply With Quote
quote:
Originally posted by I predict a Riot
It is more than likely a shaded pole type motor and therefore designed to only run one way.

Sorry


Maybe, but why the extra terminal then?

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mookaloid

posted on 23/11/12 at 09:58 PM Reply With Quote
quote:
Originally posted by Nickp
quote:
Originally posted by I predict a Riot
It is more than likely a shaded pole type motor and therefore designed to only run one way.

Sorry


Maybe, but why the extra terminal then?


Possibly the permanent live for the timer run on function?





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I predict a Riot

posted on 23/11/12 at 10:01 PM Reply With Quote
I've checked my vent axia cataloge and they no longer use that terminal notation so I really don't see why you can't try connecting the live to the spare terminal and see what happens.

You might get lucky!





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unijacko67

posted on 24/11/12 at 08:36 AM Reply With Quote
If you have room you could mount it to a bit of ply with a hole in the centre, turn it around then box the sides in.





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Peteff

posted on 24/11/12 at 08:44 AM Reply With Quote
If the blades are designed as a pusher it will not be efficient if you just reverse the motor. It will move air but not like an extractor fan. The spare terminal looks like another neutral shielded from the live and will be a dead short if you put the live in it. I would put the neutral in it first and see what effect it has.





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Nickp

posted on 24/11/12 at 09:20 AM Reply With Quote
quote:
Originally posted by Peteff
The spare terminal looks like another neutral shielded from the live and will be a dead short if you put the live in it. I would put the neutral in it first and see what effect it has.


You may be right. A0(L) and A2(N) measure 250ohms between them, possibly through a winding? A0(L) and A1(?) measure exactly the same. So, in theory it should be safe to connect the N to A1 and see what happens. It kinda makes sense too the way it's wired making it easy to swing the N between the terminals. Any more thoughts before I blow it up?

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bi22le

posted on 24/11/12 at 10:25 AM Reply With Quote
Yeah,

Its been an hour, are you still alive?!?





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westf27

posted on 24/11/12 at 10:36 AM Reply With Quote
If its a shaded pole motor (solid rotor and surrounded by coil wound stator then you can reverse the rotation by flipping 180 degrees the outer stator.If you look closeley you will see a shading ring to ensure correct rotation.





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Nickp

posted on 24/11/12 at 10:46 AM Reply With Quote
quote:
Originally posted by bi22le
Yeah,

Its been an hour, are you still alive?!?


Yeah, because I've only been painting the wood work Still plucking up courage.

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Nickp

posted on 24/11/12 at 11:20 AM Reply With Quote
It works!!

TBH, I went to rewire it and noticed instructions inside the cover where they were terminated. Saying to swing N between A1 and A2 for intake or extract, as we suspected anyway. Feel a bit daft but hey it's working now and thanks for all your help / advice

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MikeRJ

posted on 24/11/12 at 12:20 PM Reply With Quote
quote:
Originally posted by big-vee-twin
Can you get the fan blades off the motor and mount it on the other way round


Putting the fan on back to front does not change the direction of airflow! It will simply make the fan less efficient assuming the blades are and optimal shape.

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