The short answer: an Antminer wants clean, dry, moving air. Bitmain rates the whole S-series for an operating ambient of 0–40°C at 10–90% relative humidity (non-condensing), below 2,000 m altitude, in air free of salt, conductive dust, and corrosive gas. In practice, run well inside those walls — intake air in the 15–30°C band, humidity that never touches the dew point, and enough airflow that exhaust never recirculates to the fans. This guide covers the room and the air; for the temperatures the chips and boards themselves tolerate model-by-model, see the companion guide linked below.
The published operating envelope
These are the manufacturer limits for the standard air-cooled S-series (S17, S19, S21 families). Treat them as the outer wall, not the target — every degree and every percent of humidity you keep in reserve is headroom for a hot day or a failing fan.
| Parameter | Operating | Storage / transport |
|---|---|---|
| Ambient temperature | 0–40°C | −20 to 70°C |
| Relative humidity | 10–90% RH, non-condensing | 5–95% RH, non-condensing |
| Altitude | Below 2,000 m | — |
Ambient temperature: intake, not room average
The number that governs a miner is the temperature of the air at the fan intake, not the average temperature somewhere in the room. A rack can read a comfortable 25°C at head height while the units at the top of the stack are ingesting 40°C air that has already rolled off the machines below them. That is why layout matters as much as the thermostat.
As intake air warms, the firmware works harder to hold chip temperature in range. Push past the ceiling and the miner will thermal-throttle — drop frequency to shed heat — and if it cannot keep the hottest sensor safe it raises a temperature error and shuts the hashboards down to protect the silicon. You lose hashrate long before you lose the machine, so hold intake air in the 15–30°C band. Cold is cheaper than hot, but read the humidity section before running a unit in a freezing garage — the risk there is condensation, not the cold itself.
Humidity and condensation
“Non-condensing” is the load-bearing word in the spec. A miner can run in 90% humidity all day as long as water never forms on the boards. Condensation happens when a surface drops below the dew point of the surrounding air — and the classic trigger is a cold start: a unit that sat off in a cold, damp space, powered up so its boards warm through the dew point while surrounded by humid air. Liquid water bridging a bus-bar or a domain converter is a dead short.
- Never power a cold, damp miner immediately. Let it sit un-powered in the operating space until it equalizes to room temperature first.
- Avoid swinging humidity. A stable 40–60% RH is easier on hardware than a room that spikes to 90% every time it rains.
- Watch coastal and basement air. Salt-laden or persistently damp air accelerates corrosion on connectors and copper long before it ever condenses.
Dust, salt, and corrosive gas
Dust is the slow killer. It blankets heatsinks, chokes fans, and — if it is conductive or hygroscopic (salt, metal, carbon) — it wicks moisture and tracks current across the board. Bitmain publishes hard limits on airborne particulate and corrosive gas for a reason:
| Contaminant | Limit |
|---|---|
| Sand | ≤ 30 mg/m³ |
| Suspended dust | ≤ 0.2 mg/m³ |
| Deposited dust | ≤ 1.5 mg/(m²·h) |
| H₂S / SO₂ / NO₂ | 3 / 10 / 50 ppb |
| Cl₂ / HF / O₂ | 1 / 1 / 2 ppb |
| NH₃ | 500 ppb |
The practical rules that keep you under those numbers:
- Filter the intake, not the exhaust. Use washable or replaceable media filters on the air coming in, sized for low pressure drop so you don’t starve the fans, and clean them on a schedule — a clogged filter is worse than no filter.
- Keep pollution sources at distance. Bitmain’s siting guidance: at least 5 km from heavy sources (smelters, coal), 3.7 km from moderate (chemical, rubber, electroplating), and 2 km from light sources (food, leather). If you can’t, put the intake perennially upwind of the source.
- Treat the coast as corrosive. Stay 3.7 km clear of seaside and salt lakes; if you can’t, seal the room airtight and cool it with recirculated, conditioned air rather than pulling raw salt air through the machines.
- Blow out the machines periodically. Dust that gets past the filter still accumulates. Compressed air on de-energized units keeps heatsinks and fan blades clear — a dust-caked fan spins slower, runs hotter, and fails early.
Altitude and air density
The 2,000 m ceiling is about air density, not oxygen. Thinner high-altitude air carries less heat per cubic foot, so the same fan moves less mass of air and cools less effectively; it also weakens the dielectric strength of the air inside the PSU. Above 2,000 m, expect to derate — run a lower power profile, accept reduced hashrate, or move more air — and treat any manufacturer thermal spec as optimistic.
Airflow and room layout
Each unit pushes several hundred cubic feet of air per minute, front to back. The single biggest environmental mistake is letting hot exhaust find its way back to a cold intake — recirculation quietly raises intake temperature across the whole room until everything throttles.
- Separate hot and cold. Build a hard boundary between the intake (cold) side and the exhaust (hot) side — a hot-aisle / cold-aisle arrangement, a partition, or ducting the exhaust straight outside.
- Give the room a pressure bias. Slight positive pressure on the cold side (filtered air in) keeps unfiltered dust from leaking through gaps — but the hot side needs an equally large path out, or the fans fight back-pressure and heat stacks up.
- Don’t block the ends. Keep clearance at both the intake and exhaust faces; a wall too close to either end strangles the airflow the whole cooling design depends on, and intake CFM must exceed total miner CFM or the room starves itself.
Electromagnetic environment and siting
Keep the room clear of strong fields and heavy switching gear. Bitmain’s guidance: no high-power AC transformer (>10 kA) within 20 m, no high-voltage lines within 50 m, and no high-power radio transmitter (>1,500 W) within 100 m. The room should also stay free of explosive, conductive, or magnetically active dust — the same particulate discipline that protects the boards.
Related guides
For the temperatures the chips and boards themselves tolerate, read Optimal Operating Temperature Ranges for ANTMINER Models. If a unit is already throttling or throwing temperature faults, run it through the ASIC Fault Finder and brush up on thermal throttling; when a fan, filter, or heatsink needs replacing, source it from ASIC Repair Parts. If your site runs below freezing, the cold-start, condensation and winter-airflow rules are in setting up and maintaining miners in cold climates.
