1k cuft room-- 250CFM enough?

M

mkrohn

2[H]4U
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Apr 30, 2012
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would 250 CFM exhaust fan be able to keep up with my mining rack? Or do I have to go higher? I'm just gonna dryer vent exhaust and set it to a temperature based outlet so that when the room is cool enough it'll just turn off. I'm finding 250CFM nice and cheap
 
I'm thinking you are going to need more. I have box fans for inlet/outlet (2500 cfm if you trust the web) and I still have heat build up. Then again, it's been in the 70's during the day lately. With your low ambient, you could probably get away with a lot less.
 
I think it depends on where you are pulling the air from, into the mining room, that you are exhausting and the temperature of that air before it hits the rigs.
250CFM sounds low, even for a bathroom exhaust fan if I'm not mistaken.
 
When it comes to CFM actually being kicked out of a room its a bit different from just moving air. I figured 250CFM can move all of the air in that room OUT every 4 minutes and in 4 minutes there's no way that room can heat up that much. I'm probably gonna have to setup 1 as an air inlet and one for OUT. WHile its cold right now ll of this work is with summe rin mind. The room is 90 right now so when it gets hot out the inlet of hot air won' help but I do plan on a dedicated AC unit in the room too.

I'm looking for a good way to duct things out using a dryer vent. If you guys have any suggestions I'd be glad to hear it.
 
Core32 said:
250CFM sounds low, even for a bathroom exhaust fan if I'm not mistaken.
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Actually no... no, it's not. 250CFM would be one HUGE exhaust fan. The smallest value I've seen is 50CFM, the largest, about 200CFM.... I don't believe I've seen a 250CFM bathroom exhaust fan. And yes, I've been looking at them as a way of either drawing air in or out of the room.
 
I looked into it a little when I was using 3KW at the wall with my folding rigs.
The best sites I found dealing with getting rid of hot air were all hydroponic in nature...if you know what I mean :)
Take a look at those and you will find temp controlled blowers and auto open/close vent systems.
 
Core32 said:
I looked into it a little when I was using 3KW at the wall with my folding rigs.
The best sites I found dealing with getting rid of hot air were all hydroponic in nature...if you know what I mean :)
Take a look at those and you will find temp controlled blowers and auto open/close vent systems.
Click to expand...

I was just about to suggest the same thing. There are some nice inline blowers that you can get that will fit on standard size dryer vent. They certainly are designed to move the CFMs, but they're typically not terribly cheap... and from what I've read, they will probably compete with your mining rigs for which is the loudest.
 
_r2h said:
8" inline fans will do close to 800 CFM. :)
Click to expand...

I have a 4" dryer vent already there and your typical basement window that you prop open with a stick. Would an 8" getting cut all the way down to 4" still work nicely?

Think about it this way, even if I have to drop $200 on moving air out it would still likely save me at least that on my AC bill over the summer. I'm planning on sorta sealing that room off and just moving the air out as much as possible. The equipment works great with the room at 90 and here in MI there's not typically many above 90 days in a summer. I have everything spread out enough now thanks to USB risers that I believe the room staying in the 90-95 range is perfectly acceptable.

That basement window propped open will suck in enough air. I'm considering fans or an AC unit in that window also but the AC unit likely won't be needed for longer than one month.
 
I thought I saw 4" inline blowers also but I could be mistaken.
Trying to remember from my aquarium pump days but I believe if you need to reduce from 8" down to 4" it would be better on the blower output side.
Feed it with as much as it can take (input) and it will be ok pushing out into a smaller vent size.
 
Core32 said:
I thought I saw 4" inline blowers also but I could be mistaken.
Trying to remember from my aquarium pump days but I believe if you need to reduce from 8" down to 4" it would be better on the blower output side.
Feed it with as much as it can take (input) and it will be ok pushing out into a smaller vent size.
Click to expand...

Indeed, keep the intake as big as possible, you can down size the exhaust. For the most part a reducer will just increase velocity assuming there isn't too much of a restriction on the outlet.
 
yes it is on the output that I'm looking at using a reducer. For INPUT its going to be a pretty good sized window and if needed I'll create a new hole for input if I end up needed to put an AC unit in that window.
 
I like to think I have a hot/cold aisle setup almost. Box fans at one end of the house, open windows at the other end. My mining rack in the hallway between the two areas. Not a terrible way of doing things.
 
my mining is in the basement next to the furnace in a room next to the laundry room. Its kinda perfect if I get enough in/out airflow.
 
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