$/kWh
Hydro-cooled miners use closed-loop water cooling instead of fans to remove heat from ASIC chips. The result is lower noise (around 50 dB compared to 75+ dB on air-cooled equivalents), better energy efficiency, higher rack density, and longer hardware lifespan. Hydro-cooled facilities achieve PUE of approximately 1.03, meaning only 3% energy overhead beyond the miners themselves, compared to 20%+ on air-cooled data centers. Hydro miners are designed exclusively for data center and industrial hosting operations. They require 380 to 415V three-phase power, liquid cooling infrastructure, and 8 to 10 L/min coolant flow rates. They are not suitable for home mining and should not be ordered for residential deployment. The MillionMiner catalog covers 68 hydro models including the full Bitmain S23 Hydro lineup (580 TH/s at 9.5 J/TH, 865 TH/s, and 1,160 TH/s on the S23 Hydro 3U), the S21 XP Hyd (473 TH/s at 12 J/TH), and WhatsMiner Hydro variants. The majority mine Bitcoin (SHA-256), with select Scrypt and KHeavyHash hydro options for Dogecoin/Litecoin and Kaspa operations. MillionMiner's US hosting facilities support full hydro infrastructure including plumbing, flow monitoring, and pressure management. For operators building their own setups, Lianli radiators and cooling cabinets are available in the Equipment category.
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The era of air-cooled mining farms is giving way to liquid cooling infrastructure. As ASIC power densities exceed what air can efficiently dissipate — flagship Bitcoin miners now drawing 3,500W+ per unit — serious operations are moving to hydro-cooled and immersion-cooled systems that deliver dramatically lower PUE, higher hashrate density per square metre, near-silent operation, and extended hardware lifespan. We stock the full Bitmain Antminer Hydro series, Lian Li mining containers, immersion tanks, CDUs, radiators, pumps, coolant, cables, and every component needed to build a complete liquid cooling infrastructure from the ground up.
PUE Improvement
~1.03 PUE
vs 1.4–1.6 for typical air-cooled facilities
Noise Reduction
~45 dB
vs 75–85 dB for air-cooled ASICs
Density Gain
3–5×
More hashrate per m² vs air-cooled racks
Hardware Lifespan
+30–50%
Extended ASIC lifetime vs air cooling
Every mining operation runs on one of three fundamental cooling approaches. The differences in cost, density, efficiency, and operational complexity are substantial — and choosing the wrong one for your scale is an expensive mistake.
The traditional approach: ASICs draw ambient air through the chassis with high-RPM fans, exhausting hot air out the back. Every ASIC you have ever seen ships with this system built in. No external infrastructure required beyond a ventilated space and power.
Zero additional infrastructure cost
Simple setup, any location
Standard warranties and support
75–85 dB — extremely loud
PUE 1.4–1.6 — high cooling overhead
Dust ingestion degrades hardware over time
Low density — large floor area required
Best for
Home miners, small farms under 50 units, first-time operators
Hydro miners are purpose-built ASICs where the heat exchanger is water-cooled rather than fan-cooled. The ASIC chip generates heat, which transfers into a closed water loop via an internal cold plate. That heated water circulates to an external radiator (CDU) which dissipates the heat — either to ambient air via a dry cooler or to a cooling tower. The fans are eliminated entirely or dramatically reduced.
40–50 dB — near-silent operation
PUE ~1.05–1.10 — very efficient
Standard rack-mountable form factor
No chemical coolant — uses standard water
Requires external CDU / radiator infrastructure
Hoses, fittings, pumps add installation cost
Dedicated hydro ASIC hardware required
Best for
Mid-to-large farms, noise-sensitive locations, high-density deployments
Immersion cooling submerges entire ASIC hardware — boards, chips, and all — directly into a bath of dielectric fluid (engineered oil) inside a sealed tank. The fluid absorbs heat directly from every component surface simultaneously and circulates to a heat exchanger. No air moves, no fans run, no dust enters. The thermodynamics are fundamentally superior to any air-based approach.
PUE ~1.02–1.03 — near-theoretical maximum
Works with standard air-cooled ASICs (fans removed)
Highest possible hashrate density per m²
Zero dust, corrosion, or humidity degradation
Highest upfront infrastructure investment
Dielectric fluid cost & ongoing management
Maintenance access requires fluid handling
Best for
Large industrial operations, space-constrained sites, maximum efficiency mandates
A hydro-cooled ASIC is a purpose-built machine — not a retrofitted air-cooler. Bitmain's Antminer Hydro series (S19 Hydro, S21 Hydro) ships without axial fans and replaces them with an internal water block directly bonded to the hash board components. Coolant — typically clean water or a corrosion-inhibited water-glycol mix — flows through the internal block, absorbs the chip heat, and exits through quick-connect fittings on the rear panel into your external cooling loop.
The external cooling loop consists of a pump (circulating coolant through the circuit), distribution manifolds (splitting flow to multiple machines), flexible hoses with quick-disconnect couplings (tool-free machine swap), and a Coolant Distribution Unit (CDU) or radiator that dissipates heat to the environment. In cold climates, free cooling via dry coolers can bring the entire cooling system's power draw to near zero — achieving PUE approaching 1.0 during winter months.
The critical operational advantage of hydro over immersion is serviceability: a hydro miner sits in a standard rack, connects to quick-disconnect hose fittings, and can be swapped in under two minutes without fluid handling equipment. Maintenance is nearly identical to air-cooled hardware — you just unplug hoses instead of power cables. For operations that cycle hardware frequently or need rapid fault resolution, hydro cooling offers the best balance of efficiency and operational simplicity.
Chilled Water Supply
CDU or dry cooler delivers cooled water (typically 30–40°C) to the distribution manifold at the head of the rack.
Manifold Distribution
A supply manifold splits flow across all machines in the rack. Each machine connects via quick-disconnect hose fittings — no tools required for connection or removal.
Internal Cold Plate
Inside each hydro ASIC, water flows through a cold plate bonded directly to the hash board chips. Heat transfers from chip to water. Water exits 10–20°C warmer than it entered.
Return Manifold Collection
Heated water from all machines collects in the return manifold and flows back to the CDU as a combined warm stream.
Heat Rejection (CDU / Dry Cooler)
The CDU transfers heat from the closed mining loop to an external rejection loop — either a dry cooler (fan-based outdoor unit) or a cooling tower for large installations. In cold climates, a dry cooler can run with near-zero fan power.
Immersion Tank
A sealed stainless steel or fibreglass tank — typically 1,000–3,000L capacity — housing the hardware. Each tank holds 12–48 standard ASICs (fans removed) stacked horizontally in purpose-built frames. The entire interior is filled with dielectric fluid.
Dielectric Fluid
Engineered mineral oil or synthetic dielectric fluid (e.g. Engineered Fluids BitCool, 3M Novec). Electrically non-conductive so safe in contact with live electronics. Thermal conductivity ~4× better than air. Non-flammable. Reusable indefinitely with filtration. Top-up required periodically due to evaporation.
Heat Exchanger Coil
A coil of heat-exchange tubing sits submerged in the warm dielectric bath. Clean water circulates through this coil, absorbing heat from the fluid and carrying it out of the tank. The fluid and water never mix — they exchange heat through the coil wall only.
CDU / External Cooling Loop
The heated water from the tank coil flows to an external Coolant Distribution Unit, dry cooler, or cooling tower for final heat rejection to atmosphere. This is structurally identical to the hydro cooling external loop.
Filtration & Monitoring
Continuous filtration removes particulate contamination from the dielectric fluid. Sensors monitor fluid temperature, level, and flow rate. Management software tracks per-tank thermal load and flags anomalies.
Immersion cooling is categorically different from every other cooling approach because it eliminates the thermal boundary between the cooling medium and the heat source. In air cooling, heat must travel from chip to heatspreader to heatsink fins to moving air — multiple interfaces, each adding thermal resistance. In immersion, the dielectric fluid contacts every surface of every component directly. The result is chip junction temperatures 30–50°C lower than equivalent air-cooled setups running identical workloads.
Lower chip temperatures have compounding operational benefits. ASIC failure rates are directly correlated with thermal cycling and sustained high temperatures — immersion-cooled hardware routinely achieves 5–7 year operational lifespans versus 2–3 years for air-cooled machines in hard-running industrial environments. Many operators run immersion ASICs at conservative clock frequencies to maximise longevity, or overclock aggressively knowing the thermal headroom exists. Both strategies are viable in ways they simply are not with air cooling.
The other major advantage is hardware flexibility: most single-phase immersion tanks accept standard air-cooled ASICs with fans removed (fan headers bridged with a resistor). This means you do not need to buy dedicated immersion hardware — your existing Antminer S21s, WhatsMiner M60s, or KS5s can go directly into a tank with a low-cost fan modification. This is a significant capital efficiency advantage over hydro cooling, which requires purpose-built hydro-variant machines.
Both are dramatically superior to air cooling. The choice between them comes down to scale, operational style, and capital allocation.
Rule of thumb: if you need to swap hardware frequently and want minimal operational complexity, hydro wins. If you are building a fixed large-scale installation and want the absolute lowest PUE and longest hardware life, immersion wins. Many professional operations run hydro for their newest-generation hardware (where frequent rotation is likely) and immersion for older-generation machines running extended depreciation cycles.
Everything you need to build a complete hydro or immersion cooling system — from the miners themselves to every pipe, pump, and panel.
Purpose-built water-cooled ASICs. Fans replaced by internal cold plate. Quick-connect rear fittings for tool-free installation. Current lineup includes the S19 Hydro (158 TH/s), S21 Hydro (335 TH/s), and KS5 Hydro for Kaspa. Designed to integrate directly with Bitmain's own CDU systems or third-party cooling infrastructure.
Turnkey ISO-standard shipping containers pre-configured for hydro or immersion mining. Lian Li's mining containers integrate cooling infrastructure, power distribution, network switching, and physical security into a single deployable unit. Bitmain's container solutions are designed around their Hydro ASIC series. Available in 20ft and 40ft configurations — capacity 100–400 units per container.
Single-phase dielectric immersion tanks in multiple capacities (12-unit, 24-unit, 48-unit configurations). Stainless steel construction, integrated heat exchanger coil, fluid inlet/outlet connections, and top-loading access covers. Designed for 24/7 continuous operation. Compatible with standard air-cooled ASICs (fan-modified) as well as purpose-built immersion hardware.
Coolant Distribution Units (CDUs) and dry-cooler radiators for the external heat rejection loop. Bitmain's own CDU range is designed to integrate directly with the Antminer Hydro series, available in capacities from 50kW to 400kW per unit. Third-party dry coolers and plate heat exchangers available for custom system design and for immersion cooling external loops.
Circulation pumps for both hydro and immersion primary loops. Sizing from small single-rack pumps (20–50 L/min) to large facility-scale units. Stainless or brass distribution manifolds in 6-way, 12-way, and 24-way configurations for splitting coolant flow across multiple machines or racks. Balancing valves and flow meters available for precise per-machine flow optimisation.
Quick-disconnect push-fit couplings compatible with Bitmain Hydro series rear fittings (G1/4", 3/8", 1/2" options). Reinforced EPDM coolant hoses in various lengths. Dielectric fluid (single-phase engineered mineral oil and synthetic options). Corrosion inhibitor concentrate for water-glycol systems. Filtration cartridges, fluid analysis kits, temperature sensors, flow meters, and monitoring hardware.
Liquid cooling systems reward proper planning and punish improvisation. These are the mistakes that cost operators the most.
Undersizing the Cooling Loop for Future Expansion
The most expensive mistake in hydro system design. Operators frequently size pumps, manifolds, and CDU capacity exactly for their current machine count — then add units and find the system thermally saturated. Design your primary loop for 150% of your planned capacity from day one. Pump upgrades and additional CDU capacity are possible but disruptive. Manifold ports and pipe diameters are nearly impossible to expand without rebuilding the loop.
Using Tap Water Without Treatment in Hydro Systems
Untreated tap water contains dissolved minerals, chlorine, and biological material that will cause scale buildup on cold plates, corrosion at fittings, and microbial growth in the loop. Always use deionised water with a corrosion inhibitor blend specifically formulated for mixed-metal cooling systems (aluminium cold plates, copper fittings, stainless manifolds). Test the loop chemistry quarterly. A blocked cold plate from scale buildup kills an ASIC as surely as a failed fan.
Removing Fans From ASICs Before Confirming Immersion Compatibility
Not every ASIC can be safely immersed. Some machines have thermal paste formulations or capacitor types that degrade in dielectric fluid. Some firmware exhibits fan-fault shutdowns that cannot be disabled. Verify immersion compatibility with your specific hardware model and firmware version before buying a tank. Bitmain publishes immersion compatibility lists — consult them. A standard S21 Pro is confirmed immersion-compatible; other models require verification.
Ignoring Coolant Flow Rate Per Machine in Hydro Systems
Each Antminer Hydro machine has a specified minimum coolant flow rate (typically 4–8 litres per minute per unit). Under-flowing a machine causes the cold plate to overheat locally even if the bulk water temperature appears acceptable. This is a common cause of mysterious hash board failures in hydro deployments that looked thermally healthy on aggregate temperature sensors. Install flow meters at the manifold and balance per-machine flow during commissioning.
Assuming Immersion Tanks Are Maintenance-Free
Immersion tanks are low-maintenance but not zero-maintenance. Dielectric fluid absorbs water vapour and particulate contamination over time — fluid viscosity and dielectric constant degrade. Most manufacturers recommend fluid testing every 6–12 months and full fluid replacement every 2–3 years depending on operating conditions. Neglecting this leads to reduced thermal performance, potential corrosion, and in extreme cases fluid becoming slightly conductive. Budget for ongoing fluid management from day one.
Buying Hydro Infrastructure Without Confirming Site Water Supply
Hydro cooling systems require a reliable source of make-up water to compensate for evaporation losses at the dry cooler. Large installations can lose hundreds of litres per day to evaporation in hot weather. Verify your site has adequate water supply, appropriate water quality, and permission to discharge blowdown water (if using evaporative cooling towers). This is a site planning issue that has killed hydro projects after infrastructure was already installed.
Answers to the questions we get asked most before operators make the switch to liquid cooling.
Browse our full range of hydro miners, immersion tanks, containers, CDUs, and accessories above. If you are planning a new hydro or immersion deployment and want help sizing the system correctly, contact our team — we offer free system design consultations for customers building complete installations.
