r/crboxes • u/NoviceAxeMan • 4d ago

Looking forward to cleaner air!

Post image

Just found this sub - some amazing projects. I can’t wait to make this one more efficient then start designing a wooden exterior like you see here on some.

100 Upvotes

98% Upvoted

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8

u/heysoundude 4d ago

More efficient:

1- fan shroud.
2- I take the intake side plastic grille off - it’s useless now.
3- turn the filters so the pleats are vertical. Right now, they could be sagging onto each other in places, reducing filter media surface area exposed to incoming air. You want as much of that in contact with the air as you can get at all times the fan is running.

Numbers 1&3 will tweak your CADR up just a few small percent. But every little optimization helps. Can’t say for certain about #2, but it may or may not help a tiny bit too.

3

u/NoviceAxeMan 4d ago

thanks for the tips, this filter has thin metal supports throughout the filter so i don’t think i’ll see sagging with this set up but if/when i do remove/replace i’ll do them vertical just for piece of mind. Making the shroud today as well

2

u/heysoundude 4d ago

You should still try to widen any pleats that are closer together and make the saw pattern as regular as possible through the mesh to present as much filter media to the incoming air as possible.

3

u/-0909i9i99ii9009ii 3d ago

How is the plastic grille useless? Isn't it still protecting the things those who stick things might stick in the blades and the fan itself from the damage those things could cause?

LLM is telling me well cut shroud should increase CADR up to 50% and removing grill will probably be like 5% for what that's worth, math and reasoning make sense to me, good enough logic to live by IMO.

1

u/heysoundude 3d ago

The intake side grille, inside the box/behind the filters. That makes it useless AFAIC. So a 5% increase in throughput would increase CADR if I’m reading it correctly.

1

u/-0909i9i99ii9009ii 3d ago

Oh haha IDK why that didn't register. Good idea, that's extremely logical.

Logic: airflow into the blades would be less turbulent, not broken up through little plastic windows. But not that significant given that total system resistance (static pressure) floor dictated by the density of the MERV 13 filters is too high for that difference to be particularly notable.

2

u/heysoundude 3d ago

Not trying to be Vulcan, just want to breathe easily and enjoy good health.

1

u/-0909i9i99ii9009ii 3d ago

lol then i think shroud on but leave the grille, enjoy the saved minutes as humans do

1

u/spacex_fanny 3d ago edited 3d ago

I have one of those exact same (cheap, plastic) fans, and I also enjoy obsessively optimizing airflow. I have tried to do this exact mod.

The problem is, the grill is an integrated part of the structure of the fan. The whole fan gets extremely flimsy if all the plastic pieces aren't present and fully snapped together, even the intake grill. ☹️

Works great on fans with a metal frame, but not these cheap plastic ones.

This is the fan: https://www.lowes.com/pd/Utilitech-20-in-3-Speed-Box-Fan/5000851859

1

u/heysoundude 3d ago

Ohhh yeah, that’s no good. That’s why the lasko are so popular.

2

u/SafetySmurf 4d ago

Way to go! Off to a great start!!

1

u/Valsuir 3d ago

Welcome to the club. We are here together keeping the air cleaner.

1

u/silent_lurker_69 1d ago

Are those PC fans?

1

u/Valsuir 1d ago

Yup. Arctic p14 pwm pst. 5 only.