Heyo
In the summer, I stick box-fans in the windows, pulling in nice cool air and pushing off the use of AC by a couple months
Of course, since these are cheap CT fans, all they have is a rotary dial (0-3), and no real ability to automate.
I decided to add a 3 channel controller on AliExpress
Since my goal is high WAF, everything needs to work via the orinal controls. This allowed me to still use the original rotary dial, while giving me a HA override
Installation was fine, largest annoyance was the fan was original a switched neutral. Once I figured that out, I moved to a switch hot layout, and the tested. Turned on fan… Err, fine.
Threw in shoe glue as adhesive, and wire protection, and put 'er back together
How did you wire this to allow the knob to override the controller safely?
You should turn them to push air amout the window, not suck it in. That will create higher airflow. (“Source”)
I’ve tried both approaches, even some in/some out, etc.
It really depends on the space, as box fans can’t generate much pressure differential so their effect tends to be pretty localised.
In my current space I’ve found using outward in a specific window works best for overall cooling for the rest of the house overnight, but that room has a markedly higher temp.
If that fan is inward-facing, that room is 5-10 degrees (F) cooler (than using outward), again overnight.
Now if you can get a fan that handles pressure differentials (e.g. a compressor fan) then it’s a different game.
Overall I’ve found a combination of inward/outward to work best (I suspect because of the weak pressure differential of box fans), so targeting a consistent air flow velocity is what works for them.
Like your house is a big, complex PC case.
Interesting idea. I have one that I use with my indoor cycling setup, but I just have it on a Sonoff S31, so I can turn it on (the knob is set to top speed) as I warm up while riding. Then the script that starts the program on the computer also shuts off the fan when the program exits (gotta work in automation somewhere!). I like the idea of being able to control the speed.