How Big Does Exhaust Fan Need to Be?

[bgibso01]

I've been looking at some industrial warehouses and thinking about proper ventilation of a farm. Just looking for a rule of thumb kind of thing.  If I've got 300 miners with 120mm fans, that would be moving around 30,000cfm, assuming 100cfm/fan?  Since that would all be hot air, I'd want to exhaust it outside.  So does that mean I'd need at least a 30,000cfm exhaust or is there degradation in calculations like db levels?

[Amph]

well if your room temperature is fine, and your miner are working cool enough, you should be doing good already

you should aim at around 60° max, at least this with the antminer s5

[bgibso01]

well if your room temperature is fine, and your miner are working cool enough, you should be doing good already

you should aim at around 60° max, at least this with the antminer s5

There would be intake fans pulling in fresh air from outside, so that would be the room temp before going through the miners.  I'm just in the hypothetical/planning phase to see if it would make sense with a bunch of miners in a warehouse and what it would take from an exhaust standpoint.

[philipma1957]

well if your room temperature is fine, and your miner are working cool enough, you should be doing good already

you should aim at around 60° max, at least this with the antminer s5

There would be intake fans pulling in fresh air from outside, so that would be the room temp before going through the miners.  I'm just in the hypothetical/planning phase to see if it would make sense with a bunch of miners in a warehouse and what it would take from an exhaust standpoint.

room size helps  to know it,  but  

a 3000 cfm  fan changes the air  every 2 minutes   in a 20 by 30 by 10 ft room (Under perfect conditions)

So look at 3000 cfm as the exit fan and 2000 cfm as the fresh air fans as a minimum  if the room is 20 by 30 by 10.

  Many do this:

      ^^^^^^^^^ hot air leaves the building
     window window
  ^^ ^^^^^^^^^^^^^^
fan fan fan fan fan
miners miners miners
^^^^^^^^^^
fan fan fan fan
window window window

cold air outside the building

[bgibso01]

well if your room temperature is fine, and your miner are working cool enough, you should be doing good already

you should aim at around 60° max, at least this with the antminer s5

There would be intake fans pulling in fresh air from outside, so that would be the room temp before going through the miners.  I'm just in the hypothetical/planning phase to see if it would make sense with a bunch of miners in a warehouse and what it would take from an exhaust standpoint.

room size helps  to know it,  but  

a 3000 cfm  fan changes the air  every 2 minutes   in a 20 by 30 by 10 ft room (Under perfect conditions)

So look at 3000 cfm as the exit fan and 2000 cfm as the fresh air fans as a minimum  if the room is 20 by 30 by 10.

  Many do this:

      ^^^^^^^^^ hot air leaves the building
     window window
  ^^ ^^^^^^^^^^^^^^
fan fan fan fan fan
miners miners miners
^^^^^^^^^^
fan fan fan fan
window window window

cold air outside the building

Thanks Philima.  I was thinking similarly, but having 2 rows of miners with their output facing each other.  Pull outside air in on both sides, channel hot air up and out middle.  That's why I was wondering about size based on miners using 120cfm fans.  So number of miners x 120cfm to exhaust their heat without buildup.

[alh]

I think it will be at least as important to make sure the cold and hot air goes the way you want. Air should always follow the path of least resistance, and if there is a way for your cool air to get to the exhaust fan without passing through the miner, you won't get the desired result. I think it's pretty easy to create "dead spots" in terms of air flow, and a miner sitting there. I think well directed and balanced air flow is more important than the total number of CFM.

I am not an HVAC guy, so take this as a simple guys opinion.

[alh]

One additional comment. I am pretty sure that the CFM rating of a fan is "in free air" (i.e. without restriction). It wouldn't surprise me if the actual air flow through a miner was way less than the number of fans and CFM rating would suggest. The inside of a miner usually imposes serious restrictions (e.g. the S5).

[bgibso01]

One additional comment. I am pretty sure that the CFM rating of a fan is "in free air" (i.e. without restriction). It wouldn't surprise me if the actual air flow through a miner was way less than the number of fans and CFM rating would suggest. The inside of a miner usually imposes serious restrictions (e.g. the S5).

Very good point.  And I do plan on separating the hot/cold with sheating sending the middle hot air up and out, while cool air is drawn in.