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Show HN: I built an under-the-door fan duct to lower bedroom CO2

(www.lepekhin.com)
64 points bizzz | 2 comments | 24 Jun 25 14:17 UTC | HN request time: 0.419s | source

Hi HN,

This is my attempt to fix groggy mornings by lowering my bedroom CO2 from 1700 ppm to ~900 ppm.

I designed a simple, 3D-printed fan duct that directs air under the door to improve air circulation.

A note on the design process: I used CadQuery, a Python library for creating parametric 3D models. I didn't know tools like this existed and highly recommend it if you can program; it turned out to be more convenient than manually iterating on prototypes in a GUI.

The project is open source and the post explains the full build. Happy to answer any questions.

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turtlebits ◴[24 Jun 25 17:58 UTC] No.44368908[source]▶
Generating negative pressure in a room isn't great for fresh air. You'll be sucking air through any opening- wall outlets, floor registers, ceiling light fixtures, gaps in baseboard trim, etc.

Might be simpler to augment your fresh air intake with a fan.

replies(1): >>44369654 #
bizzz ◴[24 Jun 25 18:58 UTC] No.44369654[source]▶
Good point for standalone houses! I live in an apartment, so everything you listed is backed by some concrete blocks. So, realistically speaking, the air in any meaningful amounts can only come through the window/trickle vent of the door.
replies(1): >>44370299 #
1. turtlebits ◴[24 Jun 25 19:49 UTC] No.44370299[source]▶
You'd be surprised where air can leak in. Your house/building is not a closed system. You should assume that any/all wall penetrations will infiltrate air, via electrical wiring/conduit, through insulation, plumbing, hvac ducting.
replies(1): >>44374240 #
2. bizzz ◴[25 Jun 25 06:40 UTC] No.44374240[source]▶
Thank you, I did not consider it, but looks like positive pressure is a best practice and I'll be looking into that (mounting fans directly onto the trickle vent).