SunBit says Bitcoin mining can help households pay for their heating. Its installations in Finland recover heat from mining machines, while the Bitcoin they earn can offset electricity bills. But the claim of “free” heat rests on mining profitability—not superior heating efficiency—and excludes a substantial upfront investment.
A report published on November 9, 2026, at 21:49 UTC+8 describes the company’s approach and its financial assumptions. Written by CoinDesk’s Shaurya Malwa and translated by Chopper of Foresight News, it presents a small deployment with a significant unresolved question: can customers recover their installation costs before mining economics change?
Thirty installations, not a guaranteed return
SunBit CEO and founder Elmeri Suomi told CoinDesk that the company delivered its first production Bitcoin boilers in 2025 and had 30 systems operating at the time of the report. All but one were in Finland; the first overseas installation was completed in Leekum, the Netherlands, in 2025, replacing gas heating.
In Nokia, Finland, a 180-square-meter home had disconnected from district heating and was relying entirely on mining equipment for heat. Other installations included a 200-square-meter house in Kotka combining mining with an existing oil boiler, an old manor in Tampere where miners replaced wood heating, and a 3,000-square-meter industrial building in Vimpeli using mining alongside an air-source heat pump and surplus electricity from a 30-kilowatt solar array.
The system captures miners’ heat in water, reaching temperatures of up to 60°C, and distributes it through radiators or underfloor pipes. At the Tampere property, it maintained a 1,500-liter water tank at 50–60°C.
Customers buy and own the mining equipment, pay its electricity bills and receive its Bitcoin output, subject to applicable fees. Noise generally requires installation in a basement or a separate soundproofed room.
What the “free heating” calculation assumes
SunBit’s model used a Bitmain Antminer S21 XP Hydro running Braiins OS, with 495 TH/s of computing power and electricity consumption of approximately 5.3 kilowatts. Operating continuously, it would consume around 46,400 kilowatt-hours annually.
The model assumed:
- Electricity costing $0.11 per kWh, producing an annual bill of roughly $5,200.
- Bitcoin priced at $82,000.
- Total Bitcoin network computing power of 1,040 EH/s.
- Annual production of approximately one-twelfth of a bitcoin.
Under those assumptions, SunBit estimated annual Bitcoin receipts worth about $6,100 after its optional 10% service fee, with a further 0.5% mining-pool fee payable. Without the SunBit service, the modeled Bitcoin output was worth approximately $6,800 before pool fees.
The optional service included round-the-clock remote monitoring, optimization around Finland’s variable electricity prices and a mobile app. Grid-balancing functionality was planned for later.
The paid-service scenario left approximately $900 a year after electricity costs. That is the basis for describing the heat as a free byproduct. It is not a calculation showing that the equipment itself is free.
At the report’s Bitcoin price of about $81,500, SunBit put the electricity break-even price near $70,000 per bitcoin, after its service fee. That threshold excluded equipment costs and assumed unchanged network computing power. More competing mining capacity would reduce an individual machine’s expected output.
A customer example is not the same as the model
Suomi supplied a mining-pool dashboard screenshot from an early customer using a different machine: a 358 TH/s S21+ Hydro. It showed 0.039 BTC mined over the preceding year, worth approximately $3,160 at the price cited in the report. That installation could replace roughly 2,000 liters of heating oil annually, according to the account.
The screenshot was a company-supplied example, not a fleet-wide performance record. SunBit could access data from its initial pilot customers, but later customers used private mining-pool accounts whose data the company could not view.
Oil savings help; heat pumps set a tougher benchmark
For a detached home consuming 2,300 liters of heating oil annually, SunBit used an oil price of about $2.19 per liter, putting annual fuel spending near $5,000. Its replacement scenario projected approximately $920 in annual mining income after electricity costs, alongside the avoided oil bill.
Against an installation quote of roughly $20,200, excluding extras, the company calculated a payback period of about 3½ years, before maintenance and financing costs. The report separately gave a broader installed-price range of $20,400–$31,400, with estimated payback periods of three to six years. An existing oil boiler could remain available for the coldest days.
There is a practical catch: the report said the house could not use more than half the heat produced in the continuous-operation scenario. An external dry cooler discharged the excess outdoors, particularly in summer.
Heat pumps also use electricity more efficiently. The report compared approximately 2.5–3 units of heat per unit of electricity for a heat pump with roughly one unit of heat per unit of electricity for a miner.
For a home needing 25,000 kWh of heat annually, SunBit estimated annual air-source heat-pump operating costs of about $1,100, versus $3,170 for district heating. Running a miner only long enough to meet that heat demand was modeled to leave approximately $490 after electricity costs.
Suomi argued that miners maintain their heat output in severe cold, whereas air-source heat-pump efficiency falls sharply at temperatures around −25°C. Even so, the miner’s financial advantage depends on Bitcoin earnings. A heat pump’s operating economics do not depend on the cryptocurrency’s price.
The 2028 halving changes the calculation
The report identified Bitcoin’s next halving, expected in spring 2028, as the central risk to the payback projections. The block subsidy is scheduled to fall from 3.125 BTC to 1.5625 BTC—potentially before customers have recovered their installation costs.
SunBit’s calculator did not incorporate the halving into its projected payback periods. Suomi said the company explained past halvings to customers and did not promise fixed returns or predict Bitcoin prices and network computing power.
Holding the other model assumptions constant, the report estimated that mining revenue would fall from approximately $0.13 to $0.07 per kWh consumed after the halving. Against electricity costing $0.11 per kWh, that would leave a net heating cost of about $0.04 per kWh of heat, close to the heat-pump operating cost in its comparison.
Under the same assumptions, Bitcoin would need to reach approximately $131,000 to maintain the “free heating” outcome after the halving. That figure is a model threshold, not a price forecast.
The distinction matters: the boiler can keep producing heat even when mining becomes less profitable. What may disappear is the income that was supposed to pay for it.
Original article on PANews — published November 9, 2026, at 21:49 UTC+8; reporting credited to Shaurya Malwa, CoinDesk, with translation by Chopper, Foresight News.