21energy Shield
- Hashrate
- 24 TH/s
- Power
- 2,000 W
- Efficiency
- 83 J/TH
- Noise
- 70 dB
Industrial Industrial (air) Rack / shelf Discontinued
The 2016 classic that started countless home-heater builds. It is small, light and cheap on the refurbished market, but at roughly 100 J/TH it is very inefficient today. Its modest 1.3 kW draw and easy fan swaps make it a popular base for DIY space heaters.
Best price $25
$1.82 per TH · Refurbished · In stock at D-Central Store notes
Without PSU (CA$80 with an APW3 PSU)
Note from 4 Nov 2026.
| Store | Trustpilot | Condition | Availability | Listed price | In your currency | Per TH | Checked | Link |
|---|---|---|---|---|---|---|---|---|
| D-Central Ships from Canada Store notes Without PSU (CA$80 with an APW3 PSU) These notes are from 4 Nov 2026. Price and stock were checked since. | No score | Refurbished | In stock | CA$35.00 | $25 | $1.82 | 12 Nov 2026 | Visit |
| Bitcoin Merch Ships from United States | TrustScore 4.4 out of 5, 1,082 reviews | Refurbished | In stock | $200 | $200 | $14.81 | 4 Nov 2026 | Visit |
Prices as listed on each store's page on the date shown, without shipping. Prices marked excl. tax leave out VAT or sales tax, and others may too. Per TH uses the hashrate of the unit each store sells. Converted at ECB rates of 11 Nov 2026. Trustpilot scores are for the store, not the device. Each store's name opens its page, with everything it sells and its reviews.
The maker gives no hashrate for this mode, so we can't work out its mining income.
*What a pool would pay on average at today's difficulty, block reward and bitcoin price, before pool fees. Solo miners usually earn nothing, and very rarely a whole block. A plain electric heater turns the same electricity into the same heat, so the mining income is what makes the difference.
Payback is how long the bitcoin a device earns takes to add up to its price. It leaves out electricity, which buys the heat: compare earnings per kWh with your electricity price to see whether mining alone covers it. It uses the average of the last 3 months, to 12 Nov 2026: bitcoin at $79,558, 969 EH/s on the network and 3.15 BTC a block, less a 2% pool fee, for the hours you set. It cuts the block subsidy in half at each halving, the next around Apr 2028, and otherwise assumes those carry on unchanged, which they won't. Income at today's difficulty and price is about 17% below that average. Hashrate usually rises, though miners that stop paying after a halving may switch off, which leaves more for the rest. How we work it out.
| Brand | Bitmain |
|---|---|
| Model | Antminer S9 |
| SKU | — |
| Type | Industrial (air) · Industrial |
| Form factor | Rack / shelf |
| Cooling | Air |
| Production status | Discontinued |
| Launch date | Jun 2016 * |
| Hashrate | 13.5 TH/s |
| Power consumption (stock) | 1,350 W |
| Mining efficiency | 100 J/TH |
| ASIC chip | Bitmain BM1387 × 189 (named by the device's maker) |
| Heat output | 4,606 BTU/h |
| Input voltage | 11.6–13 V DC to hashboards (external AC PSU required) |
| Frequency | — |
| Net dimensions (W × D × H) | 135 × 350 × 158 mm (5.3 × 13.8 × 6.2 in) |
| Net weight | 4.5 kg (9.9 lb) |
| Noise | 76 dB * |
| Operating temperature | 15–35 °C (59–95 °F) |
| Area heated | About 9–27 m² (our estimate) |
| Colours | — |
| Company based in | China |
| Made in | — |
* Not confirmed by the maker's own documents yet.
| Version | Hashrate | Power | Efficiency |
|---|---|---|---|
| 10 TH bin | 10 TH/s | 980 W | 98 J/TH |
| 10.5 TH bin | 10.5 TH/s | 1,029 W | 98 J/TH |
| 11 TH bin | 11 TH/s | 1,078 W | 98 J/TH |
| 11.5 TH bin | 11.5 TH/s | 1,127 W | 98 J/TH |
| 12 TH bin | 12 TH/s | 1,176 W | 98 J/TH |
| 12.5 TH bin | 12.5 TH/s | 1,225 W | 98 J/TH |
| 13 TH bin | 13 TH/s | 1,274 W | 100 J/TH |
| 13.5 TH bin | 13.5 TH/s | 1,350 W | 100 J/TH |
| 14 TH bin | 14 TH/s | 1,400 W | 96 J/TH |
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Not yet confirmed from the maker's own documents: SKU; colours; where it's made; images; minimum noise; frequency; launch date.
Spotted a mistake? Let us know.