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This individual says "Without exhaust ventilation in the room, an aircon will be useless in trying to cool our rigs"

https://forum.ethereum.org/discussion/7719/to-use-ac-or-not
What does he mean by that??

I thought the aircon will also get rid of the hot air from the GPU?

Any experts know if he right or wrong?


Also is this true?


Found here https://bitcointalk.org/index.php?topic=1834513.0

Not exactly an expert on cooling, airflow, or ventilation but basic logic tells me that using an air conditioner will make the room cooler, which in turn makes the air being sucked by your GPUs / fans cooler.

I would not say that an aircon is at all useless in cooling mining rigs. The above statement might have been an exaggeration.

why instead to buy expensive aircon you run your miners slower?
just do an easy undervolt to get:
PRO
1) less consume
2) less temperature
3) less noise

CONS
1) Less gains: but i think you can reach a good compromise

and furthermore, you need this compromise, just for the summer... for the other 8 months you can run your miners at full throttle

Not exactly an exaggeration, pretty sure their main point was that it is uneconomical to use A/C. Using window or home air conditioners will almost double the cost of electricity used. Depending on rates in your area that can easily kill profits in a heartbeat. It is helluvalot cheaper just to draw relatively cooler outside air into the room and exhaust the hot air out.

It means: Without using a system that sucks the air, a use of air-con is useless in trying to cool the rigs.

Not totally by itself (for significant improvement). There's still the need for another fan to blow the air into the GPU's (will explain everything below).

He's kinda little bit of both, since a simple air flow does the trick.

Yes, it's true but take note that a large fan isn't needed if you'll be using 1 or 2 GPU's only (a single small to medium fan does the trick, even if it's a cheap one with weak intensity).

---

From my own mining experience (as of late):

Intensity of 23
GPU with it's own fans alone = at 75% fan speed is at 75°c
GPU with it's own fans + air-con= at 70% fan speed is at 72°c
GPU with it's own fans + air-con + an excess fan that directs the cool air into the GPU and pushes it away from GPU = at 65% fan speed is at 61°c-65°c

---

Some notes:

1. Not all GPU's are the same and it could affect the way you could improve the heat issues
   a. Different types of fans (not sure if a blower type of GPU can have a further improvement with an excess fan since never had one, although I'll be getting one by tomorrow and will try to update this post in the coming days)
   b. Direction of the airflow in each GPU is different
   c. The type of casing for the GPU's matter as well (open type, close type)
2. As much as possible, don't go beyond 75% fan speed and 75°c (I've seen some go beyond it but wouldn't recommend it since the GPU and it's own fans life, reduces significantly).

Back to topic pls. Put economics aside because there is a possibility that i can get a room with central air-con on 24/7 at an industrial building. Thus, that is not an issue.

The issue is is there a need to remove air from an air-con room, if u are mining in it?
Will all the hot-air produced cause some kind of issue, if it was not removed? I can have air-con and some small fan blowing the cold air to the gpu

Then the question becomes: How many miners (Watts) are you looking at and what is the cooling capacity of the A/C for the room?

Just having A/C is a fine start but it MUST be sized to the heat load being moved In most cases A/C for a general-purpose room is only as much as needed to keep it comfortable and does not take into account having several multi-kw heaters in it! I hope it does not have to said that the cooling capacity must exceed the miners heat output otherwise temps go up...

For your and others ref since most folks seem to have no idea how to search, 1Watt= 3.41BTU. Assuming a nice round 1,500W per miner, say an s9, that means 5,155-BTU of heat produced from each one.

This is gpu mining. I dont think it needs that much cooling right?

Lets say, for arguments sake, we put the air-con strong enough in the room since we can increase it and we get it free for this location. Now, is there a need to still remove the hot air in the room that is generated by the GPUs??

a) A GPU miner with multiple cards for altcoins can use just as much power as an ASIC-based one for BTC. Watts are watts....

b) As for "Now, is there a need to still remove the hot air in the room that is generated by the GPUs??"
....  ::) Hot air?? WTF do you think the A/C is doing? If the air temp in the room is still hot then the A/C is too small.

What is so difficult about grasping the concept of needing to know how much power (heat) you are putting into the room to determine how much cooling is needed to remove said heat? Power used and cooling needed to remove it are joined at the hip, 1 sets the limit to the other.

You really need to think through what you are doing before asking the same question over and over. Stop with the 'can add more' and apply NUMBERS as in how much power is available in KW and how much cooling is available in BTU. Only by knowing at least one or the other can you start getting an answer.

*IF* you are using standard mechanical air conditioning to cool a room, you don't need to have ventilation.

 You DO need to have BTU capacity in the A/C to at least match the BTU heat generation of the gear in the room in such a case.


 It's possible to set up an A/C in such a way that it puts cooler air into the "cool side" of a ventilation system, but that's NOT the norm for standard mechanical A/C systems.


 If you are using Evaporative cooling type A/C, then you DO need to be able to vent the air out of the room.


 GPU mining can use just as much power and generate just as much heat as ASIC mining does - though most GPU rigs *PER RIG* use less power than most current ASIC miners, the TOTAL wattage/BTUs still adds up.

U are not reading the question at all.....
Question is is there a need to remove the air in the room, when aircon is strong enough to cool the air...and nothing else.



Noted on standard a/c and evaporative a/c. I guess it works differently somehow such that evaporative A/c needs the air removed.
For standard a/c, are u saying there is a need to modify the a/c somehow. I refer to the text in bold.
Do u know if the central air-con's in office buildings tend to be standard a/c or evaporative a/c.
Yep, am aware of the heat issue. Can possibly use a fan to point the cold air to the GPUs. Can always put a few GPUs per room or something as we have space.

Evaporative A/C works by flowing air through some sort of "media" that has water on it.
 
 If you don't exhaust that humid air, it just keeps building the humidity level in the air 'till the water stops evaporating - and when the water stops evaporating, it stops cooling anything.


 If you are flowing air through a room, you can place a standard mechanical A/C unit (or the outlet for one on a split-phase or central unit) in such a way that it directs it's cold air into that flowing air, causing it to cool some.



 Specific areas in the West that are arid or semi-arid climates (most of Arizona and New Mexico, central Washington state, the Imperial Valley and Mohave Desert areas of California, among others) will have fairly widespread usage of evaporative cooling, but most areas use mechanical A/C.

 I am not aware of a "central A/C" setup for a large building that uses Evap cooling, but I suspect they exist - I have seen such setups for small buildings and homes.

 You could put your miners in such a position that the exhaust from the miners points at a return air duct, if such exists, for your building's central A/C - should help keep the temperature in the room lower while the A/C is flowing air.

 Depends on the building - some have louvers in doors for return air via the hallways, some have ducting for return air.

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?

You have to exhaust the hot air produced by the miner away from the miner (probably dump that outside)

If you recirculate the hot air produced by the miner into a central air conditioning system, you are wasting energy

You want to be able to cool the coldest air available, to reduce the amount of energy needed. If you are cooling the exhaust air from the miner, that is most likely the hottest air available

 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.

A dehumidifier does not lower temp and if it is a stand-alone unit it will actually ADD heat to the room. Why? Because it *is* an air conditioner but the hot side of it exhausts into the same room that the cold side is drawing moisture from so heat that is absorbed on the cold side comes out the hot side PLUS all power it takes to run the compressor in the dehumidifier is turned into heat adding to what comes out the hot side. Net result is that as far as the thermals go, it acts like a several hundred watt heater.
TINFL - There Is No Free Lunch!

 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.

That's what Heinlein's acronym was! Been a long time since I read The Moon is a Harsh Mistress ergo the memory error... (think that is where it came from)

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



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.

 ::)
And to assume that someone who has designed/built sealed enclosure multi-kw power electronics systems for decades which utilize either chilled water or mechanical cabinet coolers to move said heat loads elsewhere does not know 'what is possible' and what can actually be done is simply dreamy-eyed ignorance of the laws of nature. Some folks here <raises hand> design high power industrial electronics systems for a living, others work in HVAC systems and some in other specialized fields. Not many perhaps but there *are* technology experts here. Point is some folks here DO know what is possible with today's technologies and what is not-possible even with tech upcoming in the foreseeable future..

Yes it is easier to remove heat from dry air per-cubic foot moved but that is because the moisture itself holds a substantial amount of Latent Heat to begin with. By the same token, cool somewhat humid air is better at cooling things/people because it can absorb more heat with a lower rise in temp vs dry air.

Problem you do not see is that, great: You are using a separate dehumidifier to remove the moisture (and additional heat stored in the moisture). Fine. Thing is - you are using energy to pull out x-amount of moisture per-hour and that takes a fixed amount of energy to condense out. Doing that with a separate dehumidifier ahead of what the main cooling can do is less efficient simply because you are now using another point of mechanical effort instead of the 1 one big one. If properly sized the 1 big A/C unit will remove the humidity AND still provide proper amount of cooling all the while consuming less additional power vs running 2nd motor.

Perhaps you should read up a bit on Thermodynamics along with some textbook on heating/cooling principals 101?

TANSTAAFL

That said, a portable A/C unit like this which draws in outside air for the hot-side and exhausts the heat to the outside using ducts http://www.globalindustrial.com/p/hvac/air-conditioning/commercial-portable-ac/industrial-portable-air-conditioner-2-ton-w-cold-air-nozzles-21-000-btu-230v?infoParam.campaignId=T9F&gclid=CJf189LJvdQCFZ23wAodJP4Ldg would certainly work -- at the cost of using more electric but at least you won't be screwing with the building HVAC system.

 He used it a few places, but I think Moon was probably the first.

Yep, no offense but it is silly to assume such and more complex things have and continue to be done everywhere..... It could be something u missed. We are but fallible humans. This thread was just to explore possibilities. U dont have to put so much emotion into it u know -.-

So, while it is in-efficient, I see that it can be done. I probably need a small dehumidifier as my area is too humid anyways. High humidity will cause antminers to rust. The central air-con is not the evaporative type and will not remove humidity or hot air, it just blows cold air out and thats it.

Noted all your comments.

Anyways, noted your comments.

::) ::) ::) Oh Lord...
And where does the cold air come from? Another dimension? No -- there are always intake vents where warm/hot/humid air is sucked from the rooms/area which leads into the A/C system where it is cooled and dehumidified then blown out again...

Since you refuse to heed what experts who do this for a living and are trying to educate you in the basics have to say, now the Willfully Clueless Dreamer Ignore button is activated.

Will u relax. I do appreciate your input u know. But your approach to replying on the other hand.....
I already plan to get a window on top of dehumidifier and a fan to blow out the air. The central air con should be weak and gotta arrange it somehow such that the dehumidifier is effective despite the air going out.
I suppose u hold a technical job and have never worked as a customer service role before lol

Ventilation is the least expensive and most energy-efficient way to cool buildings. Ventilation works best when combined with methods to avoid heat buildup in your home. In some cases, natural ventilation will suffice for cooling, although it usually needs to be supplemented with spot ventilation,