Blow vs suck air over hotend's heatsink

  • I've build a 3D printer from sourced parts and mounted the hotend cooler to blow air over the heatsink.

    Talking to a friend, he said it's better to reverse the airflow over the heatsink, but couldn't give me an argument other than everywhere he saw it was like this: all coolers are mount to suck the hot air away from the heatsink.

    Is it one way better than the other way ? And if so, why ?

    I think it also depends on th design of the radiator and how the fan is mounted on it. Some pics?

    I am very confused if this radiator talk. A radiator like my car has in not in my printer. Do you mean the heater element? Ie the hotend or heated build plate? Or do you mean the cooling fins? That could kind of be called a radiator. In that case blow on not suck. Does sucking at your hand cool it?

    It is unclear to what you are referring to, by your use of the term "radiator" - Could you add a photo of the "radiator"? Do you mean _heatsink_? Or have you installed an additional cooling mechanism?

    Sorry, yes I mean heatsink. I'll edit the question

  • darth pixel

    darth pixel Correct answer

    6 years ago

    Getting hot air from the radiator is definitely wrong idea because of few reasons:

    1. hot air can damage your fan (as they are usually not heatproof). Cold air cools the fan

    2. cold air is denser so fan can suck more cold air than hot air so cooling is more efficient (fig A)

    3. in terms of plug of radiator (with dust) it's much better to try to push cold air into plugged fan (fig C) than to suck the air from it (fig B). When flow is decreased there is higher possibility to damage the fan as it doesn't cool itself

    Of course we are talking about 3D printers with small plastic fans. Please notice (almost) all fans construction: they are designed to get air from the top of the fan and push it to the bottom (this construction prevents damaging/plugging fan motor by dust)... and their mounting wholes (or clips) are usually... naturally suggesting to direct air to the heatsink)

    enter image description here

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Content dated before 7/24/2021 11:53 AM

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