How Big Does Exhaust Fan Need to Be?

bgibso01

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Quote from: alh on July 13, 2015, 11:33:00 AM

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.

alh

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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).

alh

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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.

bgibso01

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Quote from: philipma1957 on July 12, 2015, 07:46:19 PM

Quote from: bgibso01 on July 12, 2015, 03:42:26 PM

Quote from: Amph on July 12, 2015, 02:23:48 AM

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.

philipma1957

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Quote from: bgibso01 on July 12, 2015, 03:42:26 PM

Quote from: Amph on July 12, 2015, 02:23:48 AM

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

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Activity: 1218

Merit: 1001

Quote from: Amph on July 12, 2015, 02:23:48 AM

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.

Amph

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Activity: 3248

Merit: 1070

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

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Activity: 1218

Merit: 1001

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?

Topic: How Big Does Exhaust Fan Need to Be? (Read 1220 times)