Single-Phase Immersion Cooling

Single-phase immersion cooling submerges mining hardware in a tank of non-conductive dielectric fluid that absorbs heat but never changes state. The fluid stays liquid from start to finish: it picks up heat directly off the boards and chips, a pump pushes the warmed fluid to a liquid-to-liquid or liquid-to-air heat exchanger, and the cooled fluid returns to the tank in a continuous closed loop. Because nothing boils, the system runs at modest pressure and tolerates a wide range of fluids, which is why it dominates real-world Bitcoin mining deployments today.

Why it suits ASIC mining

The dielectric fluid contacts every surface of the board, so there are no hot spots and no fan noise. Operators commonly hold chip temperatures around 40–55°C instead of the 70–85°C typical of air cooling. Cooler silicon means less thermal throttling and longer hardware life, and the thermal headroom lets some operators push modest overclocks for extra hashrate. Removing the fans also removes the loudest and most failure-prone components on the machine — a real consideration for a residential or small-shop deployment, where a wall of stock Antminers is simply not livable. Mineral oils and synthetic hydrocarbons (such as the ElectroCool and Shell Diala families) are the usual fluid choices because they are inexpensive, non-hazardous, and need only active circulation rather than condensers.

Single-phase versus two-phase

The contrast is with two-phase immersion, where an engineered fluid boils directly off the chips and condenses on a coil above the bath. Two-phase moves more heat per litre and needs no pump for the primary loop, but it demands sealed tanks, condensing hardware, and specialty fluids that cost orders of magnitude more per litre — some of which face regulatory pressure as persistent chemicals. Single-phase gives up some peak heat-flux capability in exchange for open tanks, cheap fluid, and the ability to lift a board out, let it drain, and put it on the bench. For nearly every mining use case, that trade favours single-phase; the exotic option earns its complexity only at extreme density.

Trade-offs and maintenance

The main costs are pumping energy, the bulk and weight of the fluid itself, and mess discipline. Untreated mineral oil can act as a mild solvent that lifts component labels and swells some plastics over time, and every service operation involves drip trays and patience. Fan-speed-sensing firmware must be told the fans are gone. Even so, maintenance remains far simpler than two-phase: a hashboard can be lifted, drained, cleaned, and serviced without specialized condensing equipment — and if it needs component-level work afterward, that is exactly the kind of job a repair bench handles routinely. Heat rejection ultimately still flows to a dry cooler, cooling tower, or water loop, so site-level efficiency depends on the rest of the plant, not just the tank.

The heat is the point

Getting started need not mean an industrial tank. Hobbyist and small-shop single-phase builds range from a single S19 in a purpose-made enclosure to a few dozen machines in modular tanks, and the engineering fundamentals are the same at every scale: enough flow to keep the fluid moving across the boards, enough exchanger area to reject the heat somewhere useful, and clean fluid-handling habits. The miners best suited to conversion are ones already off warranty — which describes most of the used market — since opening the chassis and removing fans is part of the process.

A warmed liquid loop is far easier to reuse than warm air, which makes single-phase immersion the natural bridge between mining and heating: the same loop that cools the tank can feed a heat exchanger for a workshop, a hydronic floor, or domestic hot water. For a home miner thinking like a homesteader, the tank turns waste heat into a product. For the broader method this builds on, see immersion cooling and the fluid chemistry in dielectric fluid; for the facility-side temperature envelopes, see ASHRAE thermal guidelines.