Bitcoin heaters: when mining is the by-product of warmth
An ASIC turns electricity into hashes — and then into heat. About 99% of a miner's energy ends up as heat. The Bitcoin-heater segment flips the value proposition: sell the heat as the primary product, count the BTC mined as a discount on your power bill. Born from the 2022 European energy crisis, the category now has 12+ shipping products from Heatbit, 21energy, MintGreen, and others.
The math (vs. a heat pump)
Modern heat pumps deliver roughly 3 kWh of heat per 1 kWh of electricity (COP 3.0). A bitcoin heater delivers 1 kWh of heat per 1 kWh of electricity — much worse. So for pure heating, the heat pump wins by 3×. The bitcoin heater catches up only when:
- Daily BTC mining yield offsets the 2× electricity gap (real at low electricity rates + high BTC price).
- You can't install a heat pump (rental, no outdoor unit space, condo bylaws).
- You value the heat AND the privacy/sovereignty story (self-custody mined sats).
Form factors
- Convector radiator (Heatbit, 21energy) — looks like a slim panel heater, mounts on a wall or stands on the floor. ~250-2700 W.
- Hydronic boiler (HotMine, MintGreen) — heats water for radiators or domestic hot water. Industrial scale at the high end (MintGreen ships 8.5 kW boilers to district-heating retrofits).
- Quiet chassis (MicroMiners) — repackaged Antminer S19 with sound dampening so it can sit in a living room. Loudest of the three but cheapest per TH/s.
Catalog
| Device | Power | Released |
|---|---|---|
| Heatbit Heatbit Mini | 250 W | Dec 2023 |
| HotMine HotMine 8 | 250 W | May 2023 |
| 21energy 21energy Mini Heater | 350 W | Jun 2024 |
| 21energy 21energy Bitcoin Heater 800 | 800 W | Jan 2023 |
| Heatbit Heatbit One | 850 W | Nov 2022 |
| Wattermalon Wattermalon Heater 1000 | 1000 W | Jan 2024 |
| Heatbit Heatbit | 1400 W | Dec 2024 |
| 21energy 21energy Bitcoin Heater 1500 | 1500 W | Jun 2023 |
| HotMine HotMine 80 | 2400 W | Feb 2024 |
| Heatbit Heatbit Trio | 2700 W | Feb 2025 |
| MicroMiners MicroMiners S19 Quiet | 3250 W | Sep 2023 |
| 21energy 21energy Bitcoin Heater 3500 | 3500 W | Mar 2024 |
| MintGreen MintGreen Digital Boiler | 8500 W | Apr 2022 |
Should you buy one?
- You heat with electricity already (resistive baseboards, oil-filled radiators) — yes, the bitcoin heater is strictly better than what you have.
- You heat with gas — probably not, the gas → BTU conversion is much cheaper than electricity → BTU even with mining offset.
- You have a heat pump — no, you'd be 3× less efficient. Buy a regular ASIC for the basement instead and let waste heat pre-warm intake air to the heat pump (best of both).
Hashrate values for heating products are vendor-published — most use Antminer S19/S21 boards and inherit those specs. Real-world heat output may differ from rated power based on installation.