Bitmain Antminer S21+ Hyd (338Th)

AsicProfit Support AsicProfit · 20.10.2026

They are different machines. The air-cooled S21+ runs on single-phase 220 to 277 V with fans. The S21+ Hyd is water cooled and needs a three-phase 380 to 415 V supply, a coolant loop with 8 to 10 L/min of flow, and a dry cooler or similar heat exchanger. In return the Hyd gives much more hashrate per unit, and Bitmain rates the 358 TH/s Hyd at 15 J/TH. The numbers in each version name are the rated hashrate bins.

AsicProfit Support AsicProfit · 14.10.2026

Do not use tap water. Bitmain lists antifreeze, pure water or deionized water as working coolants, each with its own pH window: antifreeze 7.0 to 9.0, pure water 6.5 to 7.5, deionized water 8.5 to 9.5. Keep the inlet between 20 and 50 C, flow at 8 to 10 L/min and pressure at or below 3.5 bar. Where frost is possible, Bitmain says to use antifreeze rather than pure water.

AsicProfit Support AsicProfit · 6.10.2026

Not necessarily. Owners on Bitcointalk report this with S21+ units and often trace it to one hashboard, a loose data or power connection, or damage from rough shipping. Test one board at a time: power down, disconnect one board's data cable and power, and see whether the rest run. Check the kernel log for chip counts on each chain. If the unit is still under warranty, contact the seller before opening it.

AsicProfit Support AsicProfit · 30.9.2026

Bitmain gives 365 days from the shipping date on the S21+ and S21+ Hyd, but only to the original buyer who bought directly from Bitmain. If you buy from a reseller, the reseller is responsible for the warranty, so ask them for the terms in writing before paying. Running the miner outside Bitmain's specified conditions, or changing settings without approval, can void cover.

AsicProfit Support AsicProfit · 29.9.2026

Bitmain rates the air-cooled S21+ at 76 dBA at full fan speed, which is about as loud as a busy vacuum cleaner and runs around the clock. A detached garage or outbuilding works for many owners, but it is too loud for living space. Owners on forums say enclosures and ducting can take some of the edge off, but every enclosure still has to move a lot of air, so heat and airflow must come first.

AsicProfit Support AsicProfit · 16.9.2026

You need a 220 to 277 V single-phase supply. Bitmain lists a maximum input current of 20 A for the 216 TH/s unit, so plan a dedicated circuit sized for it rather than a shared household socket. The machine ships with a C20 power cord. A 110 to 120 V outlet will not work, and Bitmain warns that the wrong input voltage can damage the unit. Have an electrician check the circuit, breaker and plug before you switch it on.