Is it recommended to install two fans for a sealed enclosure?

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Originally Posted by curious aardvark

Fair enough :-)

Although there has yet to be any conclusive toxicity studies - pretty sure I've read everything over the last 10 years or so.

But if you're going to concentrate any fumes in a small space without ventilation for 7 hours and then breath them all in at once - I can see where you might get issues :-)

So you basically want an in fan at the top of an enclosure facing the room and an out going through some dryer ducting and out the window.
You can print a nice adaptor for the window.

Try and avoid any direct airflow at the level of the build plate.

you could probably get away without an active exhaust as the hot air will create it's own draft - like a chmney does. But that can be an issue if it gets windy utside, so keeping up the negative pressure inside the enclosure doesn't hurt.

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I had the toilet fan on for all 7 hours. I guess it was not fast enough to suck out the fume than generation.

Let's say we are facing the front of an enclosure, do you mean one in fan between us and the enclosure and another out fan behind the enclosure directly out of the window via a duck? I see some people putting one exhausting fan vertically on top of the enclosure. Which way is better? Also, do you recommend having the filament roll inside or outside the enclosure?

As far as filament goes - it depends how warm it gets inside the enclosure. You don't want the filamnet to get warm to the point of softening and stretching.
Yeah basically fan facing the room and exhaust facing the window.

Guess you could mount the exhaust on the top, but what I was envisaging was creating a cross current that just removes the air at the top.
If you just have an exhaust fan at the top, then you will draw in air from the bottom of the enclosure that could possibly cool the print bed down.

With a fan blowing in and one sucking out at the top you shouldn't be creating any significant air flow over the print bed itself.

Well that's my theory anyway :-)

Quote:

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Originally Posted by curious aardvark

As far as filament goes - it depends how warm it gets inside the enclosure. You don't want the filamnet to get warm to the point of softening and stretching.
Yeah basically fan facing the room and exhaust facing the window.

Guess you could mount the exhaust on the top, but what I was envisaging was creating a cross current that just removes the air at the top.
If you just have an exhaust fan at the top, then you will draw in air from the bottom of the enclosure that could possibly cool the print bed down.

With a fan blowing in and one sucking out at the top you shouldn't be creating any significant air flow over the print bed itself.

Well that's my theory anyway :-)

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Thanks. Just to clarify. Do you mean it is not a good idea to add any fan near the build-plate? What is cross current?

Umm, kind of self explanatory - cross current is a current of air that that goes across - horizontally. from one side to another.
Rather than from top to bottom.
And yep - I wouldn't put any fans down near the print bed.

Hot air rises, so the hot air from the print bed and printhead will rise, with any micro particles and the cross current should take them outof the enclosure and exhaust to the outside.

I will state that I have not done this - it's just what I WOULD do if I were going to build such an enclosure :-)

So in that respect - try and match both fans so that the air flow into the enclosure matches the airflow out of the enclosure. If your exhaust is stronger than your input it will create a partial vacumn and start drawing air in from lower down, potentially cooling the printbed.

Oh man, that is a pretty... tough question. I do not really think that using two fans would be a good idea. Theoretically, it is going to work just as fine as it could, but taking into consideration the fact that you only have a small sliding window, it could be a problem, because you will be having a lot of exhaustion. Well, I am not really sure, but you could actually try it, it might actually work out. I had a similar room back in the day, that is why I was using a big air conditioner to keep the air fresh. However, I had to call for the services of waychoffsac.com, only after a couple of days, as the a/c got broken.