Pencil drawing of the 21energy Ofen Pro

Space heater Floor standing Unknown

21energy Ofen Pro

A round, stove-like first-generation 21energy heater built around one Antminer S19k Pro hashboard. It normally runs at 500 W and can go up to 1.1 kW, mining up to about 40 TH/s, and is rated for rooms up to 44 m². Sold out.

Best price $2,309

$57.72 per TH · New · Out of stock at 21energy

Reviews from Nostr ↓

Hashrate40 TH/s worst 250 GH/sbest 1.16 PH/s 136th best of 197 (the bar uses a log scale)
Power (stock)1,100 W lowest 11 Whighest 22 kW 145th highest of 199 (the bar uses a log scale)
Efficiency28 J/TH worst 100 J/THbest 8.9 J/TH 164th best of 195
Earns per kWh$0.055 worst $0.010best $0.171 164th best of 195
Heat output3,753 BTU/h worst 38 BTU/hbest 75,067 BTU/h 145th best of 199 (the bar uses a log scale)
Noise35 dB worst 76 dBbest 25 dB 8th best of 68
Price per TH$57.72 worst $539.96best $1.82 131st best of 156 (the bar uses a log scale)

Where to buy

Store Trustpilot Condition Availability Listed price In your currency Per TH Checked Link
21energy Ships from Austria · Maker's own shop TrustScore 4.8 out of 5, 1,194 reviews New Out of stock €2,075 $2,309 $57.72 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.

Heat, running cost and sats

Heat per day
—
Electricity per day
—
Mining earns per day*
—
Net cost per day
—
Net cost per kWh of heat
—
Solo: chance of a block per year
—
Earns per kWh, on 3-month averages
—
Payback
—

*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.

Specifications

Brand21energy
ModelOfen Pro
SKUH-21-OFP-XXXXXXX-N-X
TypeSpace heater · Home
Form factorFloor standing
CoolingAir
Production statusUnknown *
Launch date—
Hashrate40 TH/s
Power consumption (stock)1,100 W
Mining efficiency28 J/TH *
ASIC chipBitmain BM1366 × 77 (reported by an independent source)
Miner inside1 x Bitmain Antminer S19k Pro hashboard
Heat output3,753 BTU/h
Input voltage230 V AC
Frequency50 Hz
Net dimensions (W × D × H)390 × 390 × 580 mm (15.4 × 15.4 × 22.8 in)
Net weight33 kg (72.8 lb) *
Noise35 dB
Operating temperature50 °C
Area heated44 m² (maker's claim)
Colours—
Company based inAustria
Made inAustria

* Not confirmed by the maker's own documents yet.

Heat modes

ModeHashratePowerHeat
Standard—500 W1,706 BTU/h

Features

  • One Antminer S19k Pro hashboard inside
  • Standard 500 W setting, up to 1100 W
  • Cylindrical steel housing
  • CE compliant

Reviews

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Sources and data notes

Not yet confirmed from the maker's own documents: weight (manual ca. 33 kg vs product page 35 kg); efficiency; colours; production status; launch date; whether prices include tax (older page says 'incl. VAT & shipping', newer pages say excl. VAT).

Spotted a mistake? Let us know.