The ANTSPACE HK3 is a container-scale hydro-cooling plant: hydro Antminers (S19 XP Hydro, S21 Hydro and the like) reject heat into a closed coolant loop, that loop dumps its heat through a plate heat exchanger, and an open cooling-tower loop with spray pumps and fans throws the heat to atmosphere. Because the whole hashcenter rides on that water loop, a lost pump or a fouled tower can put a container into thermal shutdown in minutes. This is the daily walk-around that catches a fault before it becomes a wall of overheat alarms.
The daily inspection checklist
Do this every operating day, ideally at the same time so you can trend the numbers. Work top-down from the control panel out to the tower, and log actual values — not just “OK” — so drift shows up before failure.
- Read the alarm and status page first. Clear or acknowledge nothing until you understand it. Note any coolant-temperature, flow, level, or pump-fault flags. An alarm that self-cleared overnight is still a data point.
- Coolant temperature in vs. out. Confirm the miner-loop supply and return temperatures are within the HK3’s configured band and that the delta across the fleet is stable day-over-day. A rising return temp at steady load means the tower or exchanger is shedding less heat than it did.
- Coolant level and loop pressure. Check the expansion/makeup reservoir against its min/max marks and the loop pressure gauge. A slowly falling level points to a weeping fitting or seal; a falling pressure with a steady level points to trapped air or a failing pump.
- Walk the loop for leaks. Look and feel along manifolds, quick-disconnects at each hydro miner, hose barbs, and the heat-exchanger flanges. Dried mineral crust or a damp patch is an early leak. Any dripping onto electrical gear is a stop-work item.
- Spray-pump operation. Confirm the running pump(s) are on, quiet, and not tripping. Note current draw if metered. Verify any standby/duty rotation is healthy so one pump isn’t carrying the plant 24/7.
- Cooling-tower water level and makeup. Check the tower basin float/makeup valve and the water level. Low basin water starves the pumps and lets them cavitate; an overflowing basin means the makeup valve or float is stuck.
- Tower fans. Confirm each fan is spinning the correct direction, drawing balanced current, and free of abnormal vibration or noise (see below). Look for debris in the protective net and standing water where it shouldn’t be.
- Fill media and water condition. Eyeball the tower fill and basin for scale, sludge, algae, or biological slime — cloudy or smelly basin water is both an efficiency and a health problem. Note ambient temperature and humidity too, since an evaporative tower loses capacity as wet-bulb rises: a hot, humid day that pushes coolant temps up is physics, not necessarily a fault.
Spray pumps
The spray (circulation) pumps move tower-basin water over the fill so the fans can evaporate heat off it. They are the single most common failure point in the heat-rejection loop, and they are three-phase mains equipment — treat the motor terminal box as a shock hazard even when the hashboards and their low-voltage DC are not.
A spray pump breaks down into the pump body, impeller, mechanical seals, motor, fasteners, and pump head; order spares against the exploded diagram for your exact pump, since impeller and seal dimensions vary by model.
Common pump faults and what they mean
- Motor will not start. Power-supply failure or a faulty control circuit. Verify incoming power and the three-phase connection sequence — a swapped phase can also spin the pump backwards, which moves little water and looks like low flow.
- Insufficient flow. Blocked suction line, air ingress on the inlet, or a leak at the motor/impeller joint. Inspect the strainer and pipework and replace the wear ring if it is worn open.
- Excessive power draw. Mechanical overload or worn motor bearings. Correct the overload cause; if the bearings are gone, replace the pump per the manufacturer’s guidance.
- Excessive noise. Internal damage, a worn motor bearing, or air trapped in the pump (cavitation). Bleed air, then replace the internal parts — or the whole pump — if noise persists.
- Motor overheats. Current overload or insufficient water at the inlet. Check the alarm log and confirm the basin water level is high enough that the pump is not running partially dry.
Cooling-tower fans
Each fan is an impeller, a transmission/drive, a protective net, and a motor. Do not dismantle or file the blades — they are balanced as an assembly, and a modified blade throws the fan out of balance and destroys the bearings. The mounting frame must be rigid enough to absorb the fan’s vibration and carry its full rotating load.
Fan operating limits
After start-up, check the vibration level: it must not exceed 7 mm/s RMS. If it does, stop the fan immediately and find the cause — a fouled blade, loose fastener, or dying bearing — before it takes the motor with it. After the first 50–75 hours of operation, re-check the wind-blade U-bolts for looseness, then fold that into routine preventive maintenance along with cleaning the blades and net.
Typical fan-failure signatures are vibration and abnormal noise, three-phase current imbalance, motor current running above its rated value, and low airflow. Any of these on the daily walk-around is a same-day investigation, not a “watch it” item.
Beyond daily: periodic checks
- Every six months (or sooner in harsh service): test and, if needed, replace pump mechanical seals, and check pump and fan bearings for rough or noisy rotation.
- Water treatment: keep a basin dosing/bleed regime running so scale and biological growth don’t choke the fill and exchanger. Open evaporative towers are a known Legionella reservoir — treated water is a safety control, not just an efficiency one. On the closed miner-side loop, verify coolant inhibitor/glycol condition on your unit’s documented interval; degraded coolant corrodes cold plates and manifolds.
Safety and common mistakes
- Water and three-phase power share this cabinet. Lock out and tag out a pump or fan motor before opening its terminal box. The hashboards’ DC bus is low-voltage, but the pump/fan mains supply is lethal.
- Don’t top up a leaking loop and walk away. Chasing a falling coolant level with makeup water hides the leak until a fitting lets go under load. Find and fix the source.
- Don’t let the basin run low. The fastest way to kill a spray pump is cavitation from a starved basin — check the makeup valve, not just the water line.
- Don’t dry-run or reverse a pump. After any electrical work, confirm rotation direction and that the pump is primed before committing the fleet to it.
- Don’t wave off a “self-clearing” thermal alarm. An intermittent overheat flag is usually the first symptom of marginal flow, not a glitch.
Escalation
If coolant temperatures keep climbing at steady load after pumps, fan, basin level, and water condition all check out, the plate heat exchanger is likely fouling and needs cleaning — a scheduled task, not a field bodge. If a pump trips repeatedly, a fan exceeds its vibration limit, or you find electrical damage in a wet enclosure, isolate that circuit and gather the plant documentation and correct spares before re-energizing. When a container is drifting toward thermal shutdown, throttle or pause the affected miners first — a lower hashrate beats a fleet-wide overheat.
Related: Match spares to your unit with the ASIC repair parts catalog, brush up on the difference between loop types in the hydro-cooling glossary entry, and when a fault is beyond a daily walk-around, start a repair with us.
