Immersion Cooling: Liquid Cooling for Bitcoin Miners

Immersion cooling is a liquid-cooling method that submerges electronic hardware in a fluid that carries heat but not electricity, so the fluid, not fans, takes the heat away. In Bitcoin mining, immersion cooling and hydro cooling are the two liquid alternatives to air cooling. Hydro cooling, also called water cooling, pipes coolant through the machine instead of submerging it.

Why Do Bitcoin Miners Need Cooling at All?

Nearly all the electricity a Bitcoin mining machine draws ends up as heat, so the machine needs a cooling system that carries that heat away for as long as it runs. An application-specific integrated circuit (ASIC) is a chip designed for one particular task rather than for general-purpose computing. Bitcoin mining machines are built on ASICs designed for the hash calculations Bitcoin mining requires.

In an air-cooled Bitcoin mining machine, fans pull room air across the hashboards and blow the heated air out of the machine. A hashboard is a circuit board that carries the machine’s ASIC chips.

Bitmain’s Antminer S21 XP, an air-cooled model, shows what air cooling depends on. As of October 2026, Bitmain rates the S21 XP’s power draw at 3,645 W with an inlet air temperature of 25 °C, meaning the air entering the machine is at 25 °C.

Air cooling also brings noise. As of October 2026, Bitmain lists the Antminer S21 XP at 76 decibels (dBA) at maximum fan speed, a figure that matters wherever people live or work near the machines.

How Does Immersion Cooling Work in Bitcoin Mining?

Immersion cooling in Bitcoin mining places the whole machine in a tank of dielectric fluid. A dielectric fluid is a liquid that conducts heat but does not conduct electricity. Because the fluid does not conduct electricity, powered circuit boards can sit in it without short-circuiting.

In an immersion setup, the dielectric fluid absorbs heat directly from the chips and circuit boards and then passes through a heat exchanger. A heat exchanger is a device that moves heat from one liquid into another. Here it hands the heat to a separate water loop, which releases the heat through dry coolers or cooling towers.

A dry cooler is a unit that cools the water in a cooling loop with the surrounding air. A cooling tower also cools a water loop with the surrounding air, and some designs use up water in the process.

Immersion cooling comes in two forms. In single-phase immersion, the fluid stays liquid and is pumped or circulates naturally to a heat exchanger. Single-phase fluids are oil-based, synthetic, or hydrocarbon liquids.

In two-phase immersion, a specialized fluorochemical fluid with a low boiling point boils on the hot parts. The vapor condenses on water-cooled coils at the top of a sealed tank and drips back into the fluid. Single-phase tanks, by contrast, are open or lightly sealed, which makes them simpler to maintain than the sealed tanks of two-phase systems.

Some Bitcoin mining machines are built for immersion from the start. Bitmain’s spec page for the Antminer S21 Imm., last updated in September 2024, rates the model by the temperature of the oil flowing into it, 30 °C, rather than by inlet air.

How Does Hydro Cooling Work in a Bitcoin Miner?

Hydro cooling, also called water cooling, sends a liquid coolant through a Bitcoin mining machine instead of submerging the machine. The coolant enters through an inlet pipe connector, absorbs the machine’s heat, and leaves through an outlet connector. A loop then carries the warm coolant to an external dry cooler or cooling tower, which removes the heat before the coolant returns to the machine.

A hydro-cooled ASIC sets strict terms for its coolant. As of October 2026, Bitmain’s spec page says the Antminer S21 XP Hyd accepts antifreeze, deionized water, or pure water. The coolant entering the machine must be at 20-50 °C, and the miner will not start below 20 °C. The loop has to deliver 8.0-10.0 liters per minute at a pressure of no more than 3.5 bar.

Water quality matters in hydro cooling, not only temperature. As of October 2026, Bitmain requires the S21 XP Hyd’s coolant to have a pH of 8.5-9.5, which is slightly alkaline. Bitmain also limits the coolant’s conductivity, which is a measure of how easily a liquid carries electricity. The coolant should measure below 20 microsiemens per centimeter at first run, and it must be replaced once it reaches 100 microsiemens per centimeter.

A hydro loop still depends on the temperature of the surrounding air, because a dry cooler uses that air to cool the water. As of October 2026, Bitmain’s spec for the S21 XP Hyd says its dry cooler can supply 35 °C water only when the surrounding air is at or below 30 °C. Warmer air is allowed only with warmer water, up to 45 °C air with 50 °C water.

The “Hyd” in a model name such as Antminer S21 XP Hyd refers to hydro cooling. In Bitcoin mining news, “hydro” often means hydroelectric power instead, which describes where a site’s electricity comes from, not how its machines are cooled.

What Changes on a Hydro-Cooled Spec Sheet?

Hashrate is the number of hash calculations a machine performs each second, and Bitcoin mining machines are rated in terahashes per second (TH/s). Efficiency, written in watts per TH/s (W/TH), is the power a machine draws for each TH/s of hashrate, and a lower figure is better. If TH/s is a machine’s horsepower, W/TH is its fuel consumption.

An air-cooled machine and its hydro-cooled sibling show what the cooling change does on paper. The table below uses Bitmain’s spec pages for the Antminer S21 XP and the Antminer S21 XP Hyd, as of October 2026. Bitmain gives all of these figures as typical values, with a tolerance of plus or minus 3% on hashrate and plus or minus 5% on power and efficiency.

Model	Cooling	Hashrate (TH/s)	Power (W)	Efficiency (W/TH)	Rated at
Antminer S21 XP	Air	270	3,645	13.5	25 °C inlet air
Antminer S21 XP Hyd	Hydro	473	5,676	12.0	35 °C inlet water

For the S21 XP Hyd, 5,676 W divided by 473 TH/s equals 12.0 W/TH, and for the S21 XP, 3,645 W divided by 270 TH/s equals 13.5 W/TH. Manufacturers state efficiency in joules per terahash (J/TH), which is the same number, because a watt is one joule per second.

The S21 XP Hyd delivers about 1.75 times the hashrate of the air-cooled S21 XP and draws about 1.56 times the power, at about 11% lower W/TH. The S21 XP and the S21 XP Hyd are rated under different conditions. Bitmain rates the S21 XP with 25 °C inlet air and the S21 XP Hyd at 35 °C, which a footnote on the S21 XP Hyd spec page gives as the inlet water temperature.

Bitmain’s ANTSPACE HW5 is a container that houses 210 hydro-cooled miners from the S19 Hyd. and S21 Hyd. series. On the HW5 spec page, updated in May 2026, the cooling tower’s own power use of 15-29 kilowatts (kW) is listed separately from the miners. The cooling plant therefore draws electricity on top of the miners’ listed power, which means the S21 XP Hyd’s 5,676 W and 12.0 W/TH describe the machine alone.

Why Do Bitcoin Mining Sites Use Liquid Cooling?

Trane, a manufacturer of cooling equipment, lists several reasons to use immersion cooling. Immersion cooling suits high-density loads, which means a lot of computing power packed into a small space.

Immersion cooling also needs fewer fans and less equipment for moving air, according to Trane, so a smaller share of a site’s electricity goes to overhead such as cooling. With the fans gone, the machines run more quietly as well.

Trane adds that the fluid shields the hardware from dust, moisture, and oxygen. Those are a supplier’s claims, and Trane’s description does not discuss costs or drawbacks.

Heat from Bitcoin mining machines can be reused instead of released into the air. Trane notes that the warm water returning from an immersion setup suits heat recovery. One use is district heating, in which a network supplies heat to buildings from a shared source.

In July 2025, MARA, a Bitcoin mining company, described two of its Bitcoin mining sites in western Finland, in Satakunta and Seinäjoki. According to MARA, both sites feed district heating networks. MARA writes that Bitcoin miners are “increasingly utilizing liquid cooling,” but its description does not say how the machines at either Finnish site are cooled.

What Does Liquid Cooling Require?

Liquid cooling is not a free upgrade, because the machine is only one part of the system. An immersion site needs tanks, dielectric fluid, heat exchangers, and dry coolers or cooling towers. The dry-wet cooling tower on Bitmain’s ANTSPACE HW5 container also consumes 0.7-1.3 cubic meters of water per hour, according to its spec page updated in May 2026.

For someone mining Bitcoin at home or at a small scale, air cooling is usually the realistic choice. As of October 2026, Bitmain’s spec for the air-cooled S21 XP calls for a 220-277 V power supply and room air. The S21 XP Hyd needs a 380-415 V supply, a coolant loop, and an external dry cooler or cooling tower.

A “Hyd” or “Imm.” in a model name tells you the machine uses hydro or immersion cooling and needs a cooling plant built around it, and the spec sheet tells you the coolant, temperatures, and power it was rated under.