TLDR
- Finnish startup SunBit has installed 30 Bitcoin Boilers that heat homes with mining waste heat.
- A machine can earn about $900 a year above its power costs if Bitcoin stays near $82,000.
- Break-even on electricity sits just below $70,000 per Bitcoin, according to founder Elmeri Suomi.
- Installation costs $20,000 to $31,000, with a payback period of three to six years.
- The 2028 halving could push the break-even price to about $131,000.
SunBit, a Finnish startup, has installed 30 heating systems that use Bitcoin mining computers instead of traditional boilers. The machines make Bitcoin and heat at the same time.
CoinDesk reported the details on November 8. The report says the system can earn slightly more from mining than it spends on electricity.
How the Bitcoin Boiler Works
SunBit calls its product the Bitcoin Boiler. It captures heat from powerful mining computers and sends it into a home’s existing heating system.
The heat warms water to about 60°C. That water then flows through radiators and underfloor heating pipes.
Homeowners keep ownership of the mining equipment. They also keep the Bitcoin it produces.
One home in Nokia, Finland, covers 180 square metres. It has fully disconnected from the local district heating network.
Another system heats a 200-square-metre house in Kotka. A historic manor house in Tampere uses mining equipment to heat a 1,500-litre water tank.
SunBit installed its first system outside Finland in the Netherlands in 2025. Mining company MARA also runs projects in Finland that send mining heat into district heating networks. Those networks serve about 80,000 residents.
The Numbers Behind “Free” Heat
SunBit uses a water-cooled Antminer S21 XP Hydro. It produces about 495 terahashes per second.
Running all year, the machine uses about 46,400 kilowatt-hours of electricity. At $0.11 per kilowatt-hour, that costs about $5,200 a year.
At a Bitcoin price near $82,000, SunBit estimates yearly mining revenue of about $6,100 after its 10% management fee. That leaves a surplus of about $900.
Suomi says electricity break-even is just below $70,000 per Bitcoin. That figure leaves out installation, maintenance and changes in mining difficulty.
A full installation costs between $20,000 and $31,000. SunBit estimates it pays for itself in three to six years.
Heat pumps deliver about 2.5 to 3 kilowatt-hours of heat for each kilowatt-hour of electricity. A Bitcoin heater delivers one kilowatt-hour of heat per kilowatt-hour used.
Mining income can cover that gap. The setup may suit homes that now use costly oil heating more than homes with efficient heat pumps.
Bitcoin’s next halving is expected around April 2028, according to CoinGecko. It will cut block rewards from 3.125 BTC to 1.5625 BTC.
CoinDesk estimates Bitcoin would need to trade above about $131,000 to keep the heat effectively free after the halving. Higher mining difficulty would lower returns, while cheaper power or a higher Bitcoin price would raise them.
