... if you ever get a service interruption (power goes down) it will get dangerous with temperatures under +12°C for hardware.
And with under 0 and colder --- Your hardware will start to "sweat" in some seconds!
And power comes back after 1-2 minutes it will first slighlty work --- then the thin water-ice-condense will get back to liquid again and .... BUZZZZZZZZ
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Within a datacenter the airflow should not be under 16°C (and not over 23°C - some are even doing it with 26°C - cheap mass hoster!)
Humidity should be max 30% - most prefer lower!
Really hard - you have to drink water and water every minute you feel thursty
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Without wet-problems it wont be such a problem. But you cannot lower the % of dryness without climate control.
What you should really try is:
1) Cold air from outside
2) Warm air from inside your box (circulation)
==> Mix it (maybe you get a twister)
![Roll Eyes](https://bitcointalk.org/Smileys/default/rolleyes.gif)
On a cold day you will re-use more warm air (more circulation, less cold new air).
On a hot day the air will be to hot from inside, you always will get fresh air.
Well - you need ...
temp measurement
airflow control to regulate which air you need more and less for openening a cold air valve or closing the warm air circulation etc.
(reducing the fan speed or increasing the fan speed could work too for each valve/line)
But in case of power interruption maybe some warm air from inside the house would help. (3th valve)
But it wont work automatic without APC/UPS (power is down)
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