Water-cooled Bitcoin miner: how an Antminer Hydro works and who it is for

A classic Bitcoin ASIC turns 3,500 W into heat and pushes it out with two fans at 75 dB. A "hydro" ASIC does the same thing, but into a water loop: no fans, 50 dB, and heat you can reuse. At Happy Mining we have been installing Antminer Hydro machines since the S19 XP Hydro; here is what to know before choosing this type of miner.

How an Antminer Hydro works

The hashboards are mounted on cold plates through which demineralised water (or a water-glycol mix) flows. Water enters at 20-35 °C, leaves 5 to 10 °C warmer, and has to be cooled outside the miner by an exchanger: a dry cooler (fan-assisted radiator) outdoors, or a plate exchanger into a heating circuit. The miner itself only has its circulation pump and power supply left as noise sources.

The hydro machines available

• Antminer S21 Hydro: 319 TH/s, 5,100 W, 16 J/TH. The standard choice.
• Antminer S21 XP Hydro: 495 TH/s, 5,940 W, 12 J/TH. The most efficient on the market.
• Antminer S19 XP Hydro: 250 TH/s, 5,200 W. Previous generation, entry price.

Three reasons to go hydro

1. Noise

50 dB is a normal conversation. Installed in a basement, a garage or a utility room, an S21 Hydro is inaudible from the living areas, where an air-cooled S21 forces a soundproof box or a separate building.

2. Reusable heat

An S21 Hydro returns about 5 kW continuously as water at 40-55 °C. That is exactly the temperature of underfloor heating or domestic hot water preheating. With a plate exchanger and a buffer tank, the miner replaces part of the heating; the electricity consumed is no longer "lost", it heats the house, the workshop, the pool or the greenhouse. Our page on making your electricity pay with mining details the use cases.

3. Lifespan and efficiency

Without dust or fans, the hashboards run cooler and more stable. It is also on the hydro versions that Bitmain reaches its best efficiency (12 J/TH on the S21 XP Hydro).

What you need to install

• Electricity: three-phase 380-415 V. Bitmain's hydro power supplies do not run on single-phase 230 V. An electrician fits the line and the right breaker.
• Water loop: at least 10 l/min per machine, demineralised or glycol water, filtration, bleeding. Our hydro kit includes pump, dry cooler and fittings for one to two machines.
• Antrack cabinet: for several machines, the Antrack integrates power distribution, water manifolds and pump in a ready-to-connect rack.
• Heat rejection: a dry cooler sized for 5 kW per machine, outdoors, or an exchanger into your heating.

We deliver the miner configured with the matching kit, and our hydro installation guide describes filling, bleeding and start-up step by step.

Who is it for?

Hydro is for people who have three-phase power (workshop, farm, SME, recent house), a heating need to cover, or a strict noise constraint. If you are on single-phase and noise is not an issue, an air-cooled S21 Pro remains simpler and cheaper to install. If in doubt, send us your situation (available power, room, heating need): we will tell you which of the two routes pays best for you.