The label on the box promises a specific number, a clean integer that represents power, capacity, or performance. In the world of Bitcoin mining, that number is often the first thing a buyer sees and the last thing they should trust. That number depends on conditions that may not match the site where the cooler will actually run.
Gary Berwick, a sales engineer with thirty-five years in industrial cooling, stood on stage at Mining Disrupt in Fort Lauderdale during the March 25–27, 2025, conference to dismantle that trust. Speaking for a brief five-minute slot, Berwick argued that the kilowatt rating on a cooler depends on variables like weather, altitude and fluid temperature, so buyers should find out what numbers were used to generate it. At the time, Bitcoin traded at $87,393 on March 25, 2025. On October 11, 2026, it was $82,921.
Why the Kilowatt Number Needs Context
Berwick opened by addressing the parasitic load of cooling systems, noting that his research suggests immersion cooling carries a 15% loss, direct-to-chip hydro at 25%, and air cooling at 40%. He urged operators to ask cooling vendors what they actually want to cool, arguing that immersion is the most efficient path to keeping the electric bill low. But before diving into the technology, he tackled the metric itself. The kilowatt rating on a cooler is not a constant; it depends on the conditions used to calculate it. When a vendor presents a cooler with a specific power output, that number is a projection, not a guarantee.
a lot of people will sell you a cooling system and they'll call it a kilowatt.
Gary Berwick · 1:11
The speaker emphasized that the rating depends on defining conditions that vary wildly from site to site. He also noted that the kilowatts a cooling system consumes are usually quoted for the worst case, 2 p.m. on July 14th, the hottest day of the year, and that the system does much better as the weather cools down.
You have to find out what numbers it's using to generate that kilowatts.
Gary Berwick · 1:35
Houston vs. San Jose: How Weather Eats Your Capacity
To illustrate the volatility of cooling performance, Berwick presented a comparative scenario involving two identical eight-fan dry coolers manufactured by his company. One was placed in San Jose, California, a location with mild summers. The other was placed in Houston, Texas, a location with oppressive humidity and heat. The results were stark. The San Jose unit performed optimally, taking advantage of the cooler ambient temperatures to move heat efficiently. The Houston unit, however, struggled against the thermal load.
The Houston one loses 30% of capacity, and it's just weather.
Gary Berwick · 3:00
This 30% loss is not a defect in the equipment; it is a fact of physics. The same machine that removes a certain amount of heat in a cool climate removes significantly less in a hot one. Berwick said location makes a huge difference in how many kilowatts the very same cooling system can remove. He joked that he votes for Saskatchewan, where it is nice and cool. The takeaway for operators is that site selection is not just about power availability; it is about thermal availability.
The 45-Degree Rule: Where Hashrate Actually Drops
Beyond the cooler itself, Berwick shifted focus to the miners and their tolerance for coolant temperature. He showed a chart his team found of an S21 miner's hashrate relative to coolant temperature. The data revealed a surprising plateau: performance remained stable up to a specific threshold. This threshold represents a critical decision point for operators designing their thermal loops.
it really doesn't matter up to 45° C.
Gary Berwick · 2:11
If a miner can operate efficiently at 45 degrees Celsius, the cooling system does not need to work as hard to reach that temperature compared to a system designed for 35 degrees Celsius. Berwick posed a hypothetical scenario: two cooling systems, one designed for 45 degrees and one for 35 degrees. The 35-degree system costs twice as much. By choosing the higher temperature set point, operators can save significant capital expenditure and operational energy. The argument is that running hotter coolant is not a compromise; it is an optimization. It allows for smaller, cheaper, and more efficient cooling infrastructure, provided the miners can handle the heat.
Adiabatic Tricks: Misting to Shrink the Footprint
For those who still require lower coolant temperatures or operate in hotter climates, Berwick introduced the adiabatic option. An adiabatic cooler is a hybrid device that combines dry cooling with misting. By using water evaporation to lower the air temperature, the system can remove heat more effectively than a dry cooler alone. This technology allows operators to size a smaller dry cooler section while maintaining the necessary capacity.
It's a dry cooler that uses misting.
Gary Berwick · 4:27
The benefit is dual: reduced equipment size and reduced energy consumption. However, it introduces a new variable: water usage. Berwick provided data showing that an adiabatic system might only need to run its water misting for 2,200 hours a year. In the example he gave, this translated to approximately 15,000 liters of water for the entire year. While this is a small amount, it is a cost that must be calculated alongside electricity. The adiabatic approach is not a free pass; it is a trade-off between water and power, optimized for the specific climate of the site.
The True Cost: Megawatts and Liters Per Year
Berwick concluded by emphasizing the importance of total cost of ownership, calculated over the entire year rather than at a single peak moment. He showed how his company uses ashray data to model performance across all ambient temperatures throughout the year. By summing the energy required at each temperature point, operators can see the true annual cost in megawatt-hours. In his San Jose example, the yearly total came to 55.7 megawatt-hours to remove more than 10 million kilowatt-hours of heat, which he described as a very high power usage efficiency.
with variable speed fans, you can save coin as the fans slow down, pull less kilowatts as the weather gets colder.
Gary Berwick · 4:35
Variable speed fans are a key component in this efficiency equation. As the weather cools, the fans do not need to run at full speed. For those interested in seeing how these strategies are being applied in larger deployments, the discourse will continue at Mining Disrupt 2027, March 22 to 24 in Irving, Texas. Berwick’s five-minute pitch was a reminder that in the high-stakes world of mining, the details of cooling are not just engineering problems; they are financial opportunities. When this session was recorded, Bitcoin traded at $87,393; on October 11, 2026 it was $82,921.