While this seems good in principle, there are some things to keep in mind when using outside air for cooling.
1) Just exhausting air to the outside and using the room as the supply means that the negative pressure you're creating draws the air from somewhere else in the house / building. Exhausting the air out your window means the air to make up for what you're exhausting is going to be coming into the house from somewhere else. You may not feel it but it's happening.
That is what i was counting on.. the house/building temperature is not that warm, close to ambient.
2) Using an inlet and an outlet will remove this but then you have to worry about air quality, humidity, and even potentially rain. If you have a long enough duct or have one of those dryer vent covers, you'll avoid rain but humidity (specifically condensation) is a more difficult challenge. The last thing you want to have happen is for the temperature to fall below dewpoint and you start getting condensation. Probably not going to be a huge issue since the temperature change across the device is going to be positive therefore producing exhaust air that is capable of holding more moisture than the intake air; but if it's enclosed and you're taking in cold air in the winter, it could potentially cause condensation on the exterior that could mess some things up. Additionally there's debris to worry about like dust, pollen, or whatever else. This can accumulate in the heat sinks or other airflow areas and either block airflow, foul heat transfer surfaces (meaning the internal temperature rises), or even accumulate and pose a fire risk.
It doesnt get cold, and never ever close to dewpoint, but the problem is humidity and/or pollution/dust. I feel using internal building air should be fine, since its not directly coming from outside...
3) In addition to humidity, electronics may experience damage or small cracks due to excessive rate of change of temperature (called heatup and cooldown rates).
ASHRAE TC 9.9 (
This is the 2011 version which was recently superseded by the 2012 version, though it's not publicly available from what I could find) is the industry standard for this type of thing. This is all to prolong life and prevent damage or danger to the environment. The point here is that if you have this running in the winter (presumably powered by an external fan) and the hash rate goes down (pool goes down, lose connection to internet, or any number of other reasons), if you continue to pump cold air through there, that could stress sensitive components and ultimately lead to premature failure.
Interesting. Will go thru the doc after a while. Hadnt thought about heat-cool cycle causing problems.
There are some other considerations but these are the top things to keep in mind. It's not as simple as just rejecting heat to the outside. It can be done but if it was simply that easy, every data center would be doing it.
In fact i thought about this because I remembered hearing about someone (it was either amazon or facebook unsure) throwing away the air from the hot isle, and using fresh air for further cooling and using. They obviously have some expensive equipment in place to treat the air before unleashing it onto the servers....