Attic Exhausting

[minefarmbuy]

Hi personal post here.

I'm a small home miner and wanted to increase capacity and not have neighbors kill me. So exhausting through garage wall directly isn't an option. I have decent removal but want add more units and will need to increase exhausting. Been looking at whole house fans to install above miners but the cost is pretty high. These look simple to construct from high CFM gable fan, ceiling register with flex duct, and of course mounting braces from rafters. Should be able to save quite a bit with DYI, just want to make sure I'm not missing any critical differences from a pre-constructed whole house fan to building one as described. Thanks.

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[OgNasty]

Hi personal post here.

I'm a small home miner and wanted to increase capacity and not have neighbors kill me. So exhausting through garage wall directly isn't an option. I have decent removal but want add more units and will need to increase exhausting. Been looking at whole house fans to install above miners but the cost is pretty high. These look simple to construct from high CFM gable fan, ceiling register with flex duct, and of course mounting braces from rafters. Should be able to save quite a bit with DYI, just want to make sure I'm not missing any critical differences from a pre-constructed whole house fan to building one as described. Thanks.

The main piece of advice I can give is to be aware of where you'll be taking air in.  For all the air you exhaust, you will intake the same amount somewhere.

[philipma1957]

Listen  to Nasty  


you will need to feed air in.




Here are good gable fans to pull air out.

https://www.homedepot.com/p/Master-Flow-1600-CFM-Power-Gable-Mount-Attic-Fan-EGV6/205924917

I use 2 of them  in the solar array

see photo

https://i.imgur.com/5em72rF.jpg


youtube  show heat and noise shield

https://www.youtube.com/watch?v=HKlXarvBv5M&t=1s

[minefarmbuy]

Nice, I have that one in the house gable already and their 1300 above the garage where the current farm exhaust exits. I can really only support four more units, so eight total till i'm out grown. 3k CFM removal should be plenty with in door vents and/or garage door up some correct? Might as well fit for max capacity since I need to upgrade it anyway. What CFM should I hit with 8 asics? min would be around 1600 I assume? So 3k if able to adjust would be great in the summer?

[lightfoot]

Just stick them in a window, exhaust pointing out. 100% dump heat outside and if you run AC inside you should be good.

I do this with 6 old Titans, works fine.

[minefarmbuy]

Just stick them in a window, exhaust pointing out. 100% dump heat outside and if you run AC inside you should be good.

I do this with 6 old Titans, works fine.

I would if my neighbors house wasn't so close to the garage and all their window seem to be on the that same side. So the venting into attic is best alternative. I would vent straight out the through the roof but it's new and don't want to fuck with it since it rains most the year here. I don't want four units running in the house either.

To recap: build will work, not much difference from DYI from the premade unit. Ensure air flow and we're golden?

 

[minefarmbuy]

Priced out the build, can defiantly save on the fan and hopefully other items. Thoughts? Only concern was ensuring intake, any others? or other suggestions? I just want to do one duct register in the ceiling, so would 3k CFM removal be overkill for a small farm of 8 asics on a 100F day? Bout as hot as it would typically get through a few summer days here.

[banman24]

Priced out the build, can defiantly save on the fan and hopefully other items. Thoughts? Only concern was ensuring intake, any others? or other suggestions? I just want to do one duct register in the ceiling, so would 3k CFM removal be overkill for a small farm of 8 asics on a 100F day? Bout as hot as it would typically get through a few summer days here.

[...]

Yes 3000CFM will be fine for 8 units, it allows you to have some wiggle room and if you wanted to throw in one or 2 more machines you could if you wanted.

[minefarmbuy]

I wouldn't be able to run more than the eight with my power as is. Plus this is at home and I'll hope to venture out to cheaper power and bigger space if/as needed. So 3k would be plenty and the 1.6k cfm would be about the minimum then?

[banman24]

I wouldn't be able to run more than the eight with my power as is. Plus this is at home and I'll hope to venture out to cheaper power and bigger space if/as needed. So 3k would be plenty and the 1.6k cfm would be about the minimum then?

are they all s9's? I wouldn't want my farm to have "The minimum amount of cfm exhaust" I would rather have more than enough to accommodate for the few days of the year where it might get extremely hot outside. Calculating the CFM on these really isn't like hard numbers, by that I mean the fans on the machines are variable speeds. At full speed the s9's move almost 300cfm, If you take that into consideration 8*300=2400CFM. Thats worst case scenario (I would build it to those numbers), the colder the intake temp on the miners the slower the fans spin meaning the less cfm they actually move.

[minefarmbuy]

Ok great so my assumption or feeling that 3k was bout ball park for the hot weather in removal. Not everything is an antminer half of my four units are currently. Since I probably won't max more than 8 i'll look to move forward in the next few weeks with the project.

I know gable fans come with humidifiers and thermostats, but since I'll want the fan on always but not just at max I'll look and see if there are or is a way to wire the fan to reduce/gain speed at certain temps and not just shut off entirely. So far I see only dual speed models.

[philipma1957]

I see you want a single hole.  A ten inch hole is too small. You will restrict airflow.

And you are looking to move the air more then six feet.  That restricts air flow

[minefarmbuy]

I see you want a single hole.  A ten inch hole is too small. You will restrict airflow.

And you are looking to move the air more then six feet.  That restricts air flow

What I have on that HD screenshot is a 12in register with 16in duct to fit over the gable fan. I would maybe want 6ft of ducting at most. just enough to reach the fan suspended from the rafters. Thoughts on those diameters?

[philipma1957]

What I have on that HD screenshot is a 12in register with 16in duct to fit over the gable fan. I would maybe want 6ft of ducting at most. just enough to reach the fan suspended from the rafters. Thoughts on those diameters?

maybe.

I can do  12 x 1350 = 16200 watts with 2  gable fans  and no space

so  3200 cfm  is moving enough air   to cool 1350 watts

but the fans are both 12 inches the cable vents are both 16 inches

I have two not one and the spacing from the gear is under 1 foot.

if you have 8 x 1350 = 10800 watts  

your one fan is 2350 cfm

you have one 12 inch hole not 2
and you move  the air 6 to 7 feet.

I think it could work but you may be short.

[minefarmbuy]

Is the 2350 cfm a calculation factoring the length of the ducting? The one on the quick price out is 2.8k cfm. So I should move to 3k+ for sure from you recommendation?

Reason for one hole is this is our garage, need to keep it aesthetically in tack more so than what I would once I get to the point of moving to find cheaper power.

[Raymond_B]

I think Philip is simply illustrating the effect of both ductwork diameter and length.

This is a pretty good site that might help with your calculations. https://apps.engineeringtoolbox.com/air-ducts-velocity-a_27.html

[bitcoinguy123]

Take a look at my post of my setup.  I'm using similar fan and it works great.  I got the red fan with higher cfm and bypassed the thermostat switch and its running 24/7 non stop for months now. 

Here a link to my posts.

https://bitcointalk.org/index.php?topic=2312465.msg29355077#msg29355077

[minefarmbuy]

Thanks Raymond. I just wanted to understand phma's thoughts more. The link is helpful.

Btcguy, Nice, come winter I won't need as much exhaust. Is it too much stress you think to set a temp? Starting and stopping more frequently? Garage will get pretty cold, will be interesting to see what these auto fans will drop to.

[philipma1957]

Is the 2350 cfm a calculation factoring the length of the ducting? The one on the quick price out is 2.8k cfm. So I should move to 3k+ for sure from you recommendation?

Reason for one hole is this is our garage, need to keep it aesthetically in tack more so than what I would once I get to the point of moving to find cheaper power.

the image was not very  clear I thought it read 2350cfm.

but as to hole size and length of tubing.

the longer the tube = more friction
the smaller the diameter = more friction

so a 1600cfm fan with 1 foot tube length  to move  the air

and at the same 1 foot diameter moves  air a lot better then

a 2800 cfm fan with a 10 inch tube and a six foot length .

when I read your chart I saw a reducer in it 12 to 10 inches
I saw a tube six feet long
I read a 2350 cfm fan

and I thought it may not work

if the tubing is 1 foot with no reducer
the fan is 2800cfm
and the tube length is six feet I think you will be close to okay

[minefarmbuy]

Sorry, thought he picture would be bigger.

The fan and duct are 16 in.
The reducer is a 16 to 12in.
The register is 14in x 14in to 12in
yes on the 2.8k CFM

Would like to keep the green model for less draw. but the red model like mentioned is just over 3k CFM