21energy Ofen 2
- Hashrate
- 40 TH/s
- Power
- 1,000 W
- Efficiency
- 25 J/TH
- Noise
- 45 dB
Space heater Floor standing In production
The entry model of 21energy's Ofen 3 range: a slim 1 kW heater whose warmth comes from mining chips (up to 40 TH/s). Five heat levels, a thermostat mode, app and Home Assistant control. Made in Austria, shipping since October 2026; the shop quotes about one to two weeks for delivery.
Best price $1,845
$46.13 per TH · New · In stock at 21energy · excl. tax
delivery window shown Nov 11-18 (white or black, same price)
| Store | Trustpilot | Condition | Availability | Listed price | In your currency | Per TH | Checked | Link |
|---|---|---|---|---|---|---|---|---|
| 21energy Ships from Austria · Maker's own shop delivery window shown Nov 11-18 (white or black, same price) | TrustScore 4.8 out of 5, 1,194 reviews | New | In stock | €1,658 excl. tax | $1,845 | $46.13 | 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 | 21energy |
|---|---|
| Model | Ofen 3 Base |
| SKU | H-21-OF3-XXXXW40-N-X (white) / H-21-OF3-XXXXB40-N-X (black) |
| Type | Space heater · Home |
| Form factor | Floor standing |
| Cooling | Air |
| Production status | In production |
| Launch date | Oct 2026 * |
| Hashrate | 40 TH/s |
| Power consumption (stock) | 1,000 W |
| Mining efficiency | 25 J/TH * |
| ASIC chip | Not known yet |
| Heat output | 3,412 BTU/h |
| Input voltage | 230 V AC |
| Frequency | 50 Hz |
| Net dimensions (W × D × H) | 900 × 140 × 320 mm (35.4 × 5.5 × 12.6 in) * |
| Net weight | 17 kg (37.5 lb) |
| Noise | 35–45 dB * |
| Operating temperature | 10–35 °C (50–95 °F) |
| Area heated | 50 m² (maker's claim) |
| Colours | White, Black |
| Company based in | Austria |
| Made in | Austria |
* Not confirmed by the maker's own documents yet.
| Mode | Hashrate | Power | Heat |
|---|---|---|---|
| Level 1 | 12 TH/s | 300 W | 1,024 BTU/h |
| Level 2 | 18 TH/s | 450 W | 1,535 BTU/h |
| Level 3 | 28 TH/s | 650 W | 2,218 BTU/h |
| Level 4 | 32 TH/s | 825 W | 2,815 BTU/h |
| Level 5 | 40 TH/s | 1,000 W | 3,412 BTU/h |
WhiteBlack
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Not yet confirmed from the maker's own documents: dimensions orientation (published as 90 x 32 x 14 cm); minimum noise (product page says about 35 dB; manual gives max 45 dB at 1 m); launch date (first deliveries announced for Oct 2026; actual first shipment date not confirmed); efficiency (computed from the maker's power and hashrate; 21energy's page states 20 J/TH, which does not match its own 1.0 kW / 40 TH/s and 2.0 kW / 80 TH/s figures).
Spotted a mistake? Let us know.