I see. However, chances are the central air-con is not evaporative type.
How about a dehumidifier? An energy saving dehumidifier in a small room to control the air temperature and lower humidity. Humidifier will remove hot air, yes? With central air-con, some fans to blow cold air to the rigs and a dehumidifier with thermostat to keep the humidity at 40-60%, that should work yes? So, i dont need a window? What do u think?
Most likely the central air will be mechanical A/C, not evap.
A dehumidifier *IS* a mechanical air conditioner, just with a "humidity control" type setting - they do NOT "save energy".
There is ZERO point to using one in a situation with a central A/C, unless you are overloading the ability of the central A/C setup to cool the room the miner is in.
I meant energy saving model. It wont save energy of course. There are some for small rooms, easily below 50-100watts. The main reason is to keep humidity around 40-60% which is ideal for computers/data-centres/etc. My area humidity is a little higher. A secondary function would be for it to remove the moisture in the air and the hot air. While it is better to have a window, i am not sure if it is needed. I suppose it is better to have a small window, the central a/c, a dehumidifier in middle of the room and a fan to blow the cold air to the rigs.
See
http://www.goodairgeeks.com/will-a-dehumidifier-cool-a-room/ and other links.
The answer to this question is yes; dehumidifiers can help air conditioning. When a dehumidifier removes the humidity from the air, everything is left cool and dry. When the air conditioner is turned on, it will be much easier to cool air that is already dry. If the dehumidifier had not helped, the air conditioner would have had to work hard with air that was damp and muggy
It means that air conditioning can't keep up with the heat generated by their rigs.
1000 watts of rig generates about 3400 BTU of heat - that's a level of power often exceeded by multi-card rigs PER RIG, only needs 8 rigs to generate more heat than a 25,000 BTU window A/C CAN remove (and 25k BTU is HUGE for a window unit, most are quite a bit smaller in capacity).
Just to add insult to injury - that 25k A/C unit will probably need another 2700-2800 watts of power to run IT, at common 9.x SEER efficiency rating range of most window units - though on the positive side most of THAT heat gets exhausted to the outside and not into the room.
Central A/C is commonly rated in "tons" of capacity for historical reasons - a "ton" equates to 6000 BTU, and a LOT of central units are in the "5 ton" or less range, which is still only 30k BTU or less.
Large building central A/C units will be quite a bit larger - but they also have to provide A/C for a lot more space, and a lot more heat-generating humans and lights and computers and .....
TANSTAAFL
(There Ain't No Such Thing As A Free Lunch)
Some "portable" dehumidifier units have a duct to exhaust the hot air they produce to an outside area. I want to say "most or all" but I've only worked with a few of those type units.
Hmmm insult to injury? This is but a small discussion... and it is silly to assume anything isnt possible... not a good way to think.