Mining machines produce a lot of heat, which can be harmful to the hardware. For this reason using cooling systems to reduce the temperature is crucial in any mining operation. There are two methods to cool ASICs, by using airflow or by submersing the machines in dielectric coolant. A couple of weeks ago I wrote an article about immersion-cooled mining. This time I looked into air-cooling and airflow management.
This article contains the following topics:
- What is Air-Cooled Mining?
- Cooling is Crucial
- Horizontal vs. Vertical Airflow
- Air vs Immersion
- Home Mining Set-Ups
- Must See Videos
What is Air-Cooled Mining
Most machines have high-velocity fans build-in which forces air across the internal components. An airflow is needed to provide enough cool air and get rid of the heat produced by the ASICs.
In colder and moderate climates, the ambient air is used to cool the mining equipment. In cooler circumstances, creating an airflow is sufficient to lower the temperature of the rigs. In warmer climates refrigeration components like chillers, split coolers and air handlers are often applied to increase the effectiveness of air cooling. Some miners even use air conditioners to cool the ambient temperature but this is not a common practice as the power consumption of AC’s impact the profitability of the mining operation.
Cooling is Crucial
Horizontal vs. Vertical Airflow
With a horizontal airflow set-up, the racks or shelves are positioned parallel to the shortest wall or width wall. The bigger space is positioned behind the shelves, providing cool air. The smaller space is at the output side of the miners and usually close to the exhaust fans of the building to move the hot air outside. This is also knowns as a two-aisle cooling system, separating the input area (cool aisle) and output area (hot aisle).
The shelves are best positioned in a bottom-to-top set-up. If the wall of miners becomes too high and you cannot stack them until the roof, the top needs to be closed off in other to prevent hot air being spilled back to the cool area.
The wall at the output side of the miners is covered with several big industrial exhaust fans. At the intake side no fans are needed, as the suction created by the mining machines and exhaust fans will be sufficient to get cool air into the mine. Putting fans at intake to blow fresh air in, might even disturb the airflow and create hotspots.
It is recommended to use intake louvers to inhibit the entrance of rain and sand. Many operations also have air filters at intake to keep out smaller particles like dust, pollen, insects etc.. In order to bring down the temperature at intake you can also apply evaporative cooling pads or water curtains. These pads consist of evaporative curved papers which are watered from the top. When the air gets sucked through the paper pads, the water evaporates and cools down the temperature inside the mine.
In order to optimize the use of space some miners apply a set-up with two walls of machines, blowing the heat into a hot aisle in the centre. This means there are two intake sides or cold aisles. This set-up probably allows you to have more miners per m2. However, the airflow is not linear which can create hotspots and causes a higher temperature at the far-end of the hot aisle (further away from the exhaust fans).
With a vertical airflow set-up the exhaust fans are build in the ceiling, guiding the hot air outside through the roof. In many cases this set-up is preferred to be able to deploy more machines per m2. Usually the racks are positioned parallel along the longest wall / length of the building. The output of the machine fans are directed towards the inside, creating a hot aisle in the middle of the building. Just like the horizontal set-up the louvers and filters are used at the intake part of the building. Also in this design evaporative pads and water curtains can be applied.
The ceiling fans could also be used for blowing outside air into the building. In this case the cold aisle will be in the middle and the miners will point outwards to the exhausts in the side walls. This is not a common practise in mining though, because hot air goes up more easily than cool air comes down.
In both the horizontal and vertical airflow set-up you can apply the concept of an elevated floor in order to pull in the cold air. This is a common practice at traditional data centres and generally applied if there is no possibility for direct intake via an outside wall. In Bitcoin mining you do not see this very often because lifting the floor implies extra costs and complexity of airflow management. In case a container is used, the elevated floor might create the opportunity to stack more ASICs inside.
Air vs Immersion
If your mining operation is located in a warm and humid climate, space to install miners is limited or noise can results in complaints from the community, you could consider immersion cooling. When not limited by any of these factors most miners choose to have a lower initial investment and opt for the air-cooled system.
Home Mining Set-Ups
In case you want to design or improve your home set-up using air-cooling, I recommend to check-out Upstream Data. They sell the so called Ohmm™ Black Box which provides an airflow management system while reducing noise. They also provide an extensive DIY Guide, in case you want to build your own BlackBox.
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About the Author
Nico Smid born and raised in the Netherlands, living in Argentina with my family for a year now. Expert in international business development with 15 years of experience in guiding European companies doing business in the South American market and vice versa. Bought my first Bitcoin in June 2017 and went down the rabbit hole ever since. As of 2021, I started mining to create an extra income stream for my family. This triggered me to study the industry and I found it so fascinating that I created a business in the industry. I am a co-founder of Digital Mining Solutions providing various services to companies who want to mine bitcoin next to their core business. As part of my journey I decided to publish what I am learning in a weekly free newsletter called The Bitcoin Mining Block Post , focusing on market insights and trends.