Computer fans as extractor fans - follow up

[Odana]

A few months ago I posted here asking about computer fans to use as extractor fans and got lots of useful replies. Last week I went to Maplins to get bits and the men there looked rather scared and confusled. Now when I look at the Maplins site I am confusled. Could some kind soul write me a list of *exactly* what I'm meant to be getting based on the info below, so I don't confusle anyone else?

 

I need 2 fans:

 

1) This fan is to go in a 2" deep bulkhead between bathroom/living room and must blow both ways. It needs to be 80mm approx - 100mm max but small is good. Wiring will come from a light nearby but the operation of fan won't be related to the light being on/off. I understand I need a brushed, not brushless fan, and a changeover switch to reverse polarity (RLWP). Pretty funked up says 'a 3 pos. DP/DT switch could be used to do it'. I'll put grilles over the holes to pretty em up.

 

2) This fan is to go in the 100mm vent in the bathroom and only needs to extract, not blow. It needs to be round, (or can I knock the corners off a 80mm square one to squeeze it in?). Wiring comes from nearby bathroom light, but I would prefer a separate switch.

 

The first one seems the complicated one - I can't see on the website what is 'brushed' and I know nowt about switches. I am disorganised as usual and now need to get all this by next weekend. Doesn't have to come from Maplins - in fact any mail order place would be even better, if I can give them a list of what two fans and what two switches I need. Anythign else I need to add to the shopping list?

 

Helllpp? Thanks gurus!

[Keeping Up]

Fan #1 - unless the Maplins site specifically says "brushless" for any particular 12v fan then you can assume that it has brushes. An example would be this one which is 80mm across and is 1" thick.

 

I posted the switch connecting diagram in post 8 on the earlier thread. A suitable switch woiuld be this one. You need version JK30H (which is DPDT-F, locking with centre off).

 

Fan #2 - choose the fan that you like the look of, and yes you can use exactly the same one and knock the corners off (that's what I did, so that it's a tight fit in the mushroom vent hole, and it's still there 18 years later powered directly off the light fitting, ie it comes on when the light is on and goes off when the light is off)

 

Any good?

 

Edited to add: no it doesn't have to be Maplins, any mail order place could probably supply the same. Maplins are just convenient, that's all.

Edited June 20, 2010 by Keeping Up

[Artimis]

loads more choice here if Maplins dont have it

 

http://uk.rs-online.com/web/search/searchB...aram=4294965055 4294953869&selectAttribute=12Vdc#breadCrumb

[Odana]

Thanks peeps! Will go order the bits now.

 

Marvellous place, this forum....

[Bobbybass]

Fan #1 - unless the Maplins site specifically says "brushless" for any particular 12v fan then you can assume that it has brushes. An example would be this one which is 80mm across and is 1" thick.

 

I posted the switch connecting diagram in post 8 on the earlier thread. A suitable switch woiuld be this one. You need version JK30H (which is DPDT-F, locking with centre off).

 

Fan #2 - choose the fan that you like the look of, and yes you can use exactly the same one and knock the corners off (that's what I did, so that it's a tight fit in the mushroom vent hole, and it's still there 18 years later powered directly off the light fitting, ie it comes on when the light is on and goes off when the light is off)

 

Any good?

 

Edited to add: no it doesn't have to be Maplins, any mail order place could probably supply the same. Maplins are just convenient, that's all.

 

I did exactly that....knocked of the corners and stuck it into the mushroom vent...but I did put a little push switch on the grill of the vent.

My lights have individual switches so I have an option of just fan.

Bought the fan in a computer shop.....most of the ones that sell computer bits stock fans.....£4.20

They are all brushless as you can't risk comutator sparks interfering with a computer.

 

Bob

Edited June 20, 2010 by Bobbybass

[Keeping Up]

I did exactly that....knocked of the corners and stuck it into the mushroom vent...but I did put a little push switch on the grill of the vent.

My lights have individual switches so I have an option of just fan.

Bought the fan in a computer shop.....most of the ones that sell computer bits stock fans.....£4.20

They are all brushless as you can't risk comutator sparks interfering with a computer.

 

Bob

I would disagree with that. There are a few fans that are specifically sold as "brushless" and they are indeed brushless. The majority however are not sold as being brushless, and I believe that all those do have brushes.

 

The OP cannot use a brushless fan, because you cannot reverse their direction of rotation.

[smileypete]

I need 2 fans:

 

1) This fan is to go in a 2" deep bulkhead between bathroom/living room and must blow both ways. It needs to be 80mm approx - 100mm max but small is good. Wiring will come from a light nearby but the operation of fan won't be related to the light being on/off. I understand I need a brushed, not brushless fan, and a changeover switch to reverse polarity (RLWP). Pretty funked up says 'a 3 pos. DP/DT switch could be used to do it'. I'll put grilles over the holes to pretty em up.

Probably best to have 2 fans back to back, switch either one with a changeover switch.

 

Ebuyer (with super saver delivery) are pretty cheap, and do 80mm or 92mm fans.

 

cheers,

Pete.

[WotEver]

Probably best to have 2 fans back to back, switch either one with a changeover switch.

I agree. It's a safer (as in guaranteed to work) solution, and would only require a SPDT switch with simpler wiring. When i say 'guaranteed to work' I mean that it becomes irrelevant whether the fans are brushed, brushless, pancake or whatever

 

Tony