Draw air from enclosure or push it in?

Discussion in 'Power Electronics' started by optimistic realist, Sep 13, 2018.

  1. optimistic realist

    optimistic realist

    Sep 13, 2018
    Likes Received:

    I have a scooter charger that I've replaced the fan on. ATM I have the fan aimed to draw air into the charger. Can anyone tell me for sure if I should aim the fan to pull air out or push air in? Will it make a lot of difference? Thanks
    optimistic realist, Sep 13, 2018
  2. optimistic realist


    Mar 5, 2017
    Likes Received:
    You should orient it the same as the original fan. In some cases this doesn't matter. In other cases it does, particularly if the fan isn't just meant to exchange out the heated chassis air but also to blow directly in on something near it.

    If you provide a good picture of the inside of the charger that shows the air path and fan position, someone might better advise.

    The other thing to consider is whether it is rated for the same voltage and airflow rate, though depending on the environment and use scenario, it may be possible to use a different flow rate if you check the resultant temperature.
    dave9, Sep 13, 2018
  3. optimistic realist


    Oct 5, 2014
    Likes Received:
    Front of the fan, air is under compression.
    Sit in front of a desk fan and see the difference if you turn it around and now face the back.
    Having said that, it depends on the installation.
    If the fan changes the air inside an enclosure, except for losses caused by friction or inadequate sizing of outlet hole, then the air change will not be affected.
    Note that with encased heated air, the outlet hole size will need to be somewhere close to 6 times the size of the inlet.
    Ducting around the fan and directed at the charger in your instance (I imagine) will assist in cooling
    If you have problems, show a photo.
    Bluejets, Sep 13, 2018
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