SunBit says its Bitcoin-mining boilers can heat homes while mining revenue offsets electricity bills. The qualification matters: the heat is dependable, but the financial offset depends on Bitcoin’s price, electricity costs and competition from other miners.
The report, written by CoinDesk’s Shaurya Malwa and translated by Chopper for Foresight News, describes a 180-square-metre home in Nokia, Finland, that disconnected from district heating and switched entirely to mining heat. The supplied version was published on November 9, 2026, at 18:07:09 UTC+8. Its prices and profitability estimates belong to that reporting context, not current market conditions.
A boiler with a second job
SunBit’s system captures heat from mining equipment in water reaching up to 60°C, then distributes it through radiators or underfloor heating. Nearly all the electricity consumed becomes heat, while the machine also mines Bitcoin.
CEO and founder Elmeri Suomi told CoinDesk that SunBit delivered its first production boilers in 2025 and had 30 systems operating at the time of the report. All but one were in Finland, replacing or reducing gas, oil, wood or district heating.
The first overseas installation was completed in 2025 in a Dutch location rendered as “莱库姆” in the supplied source, where mining equipment replaced gas heating. Other examples included:
- A 200-square-metre home in Kotka, a southeastern Finnish port city of about 50,000 people, combining mining equipment with an existing oil boiler.
- An old manor in Tampere where mining replaced wood heating and maintained a 1,500-litre water tank at 50–60°C.
- A 3,000-square-metre industrial building in Vimpeli using mining heat alongside an air-source heat pump and surplus electricity from a 30-kilowatt solar array.
Homeowners own the equipment, pay its electricity bills and retain the Bitcoin it earns, subject to any applicable fees. Noise generally means installing the machines in a basement or a separate soundproofed room.
What “free heat” leaves out
SunBit’s model for the Nokia home used a water-cooled Bitmain Antminer S21 XP Hydro, rated at 495 TH/s and running third-party Braiins OS firmware. At approximately 5.3 kilowatts around the clock, annual consumption was estimated at 46,400 kilowatt-hours.
The company’s calculation assumed:
| Input or result | Reported estimate |
|---|---|
| Electricity price | $0.11 per kWh |
| Annual electricity bill | About $5,200 |
| Bitcoin price | $82,000 |
| Network hash rate | 1,040 EH/s |
| Annual Bitcoin production | About one-twelfth of a BTC |
| Revenue after SunBit’s optional 10% service fee | About $6,100 |
| Additional mining-pool fee | 0.5% |
| Annual surplus after electricity, with the service | About $900 |
Without SunBit’s service, the modeled Bitcoin production was worth about $6,800 annually before the pool fee. 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.
This is the basis of the “free heat” claim: mining receipts cover electricity, with heat as a byproduct. It does not mean the equipment is free, or that the initial investment has been recovered.
With Bitcoin around $81,500 at the time of reporting, SunBit put its operating break-even price at roughly $70,000 after its service fee. That estimate excluded hardware purchase costs and assumed unchanged network hash rate. More competing mining capacity would reduce an individual machine’s output.
The customer evidence was narrower than the model. Suomi supplied a mining-pool screenshot for an early customer using a 358 TH/s S21+ Hydro. It showed 0.039 BTC mined over the preceding year, worth about $3,160 at the then-prevailing price. The system could replace approximately 2,000 litres of heating oil annually. SunBit could inspect data from its first pilot users, but later customers used private pool accounts the company could not access.
The real competitor is a heat pump
SunBit compared its equipment with a home burning 2,300 litres of heating oil annually at about $2.19 per litre—roughly $5,000 a year. Its model projected an additional annual mining surplus of about $920 after electricity costs.
Against an installation quote of approximately $20,200, excluding extras, that produced a payback estimate of around three and a half years, before maintenance or financing costs. The report separately gave an installed-price range of $20,400–$31,400 and estimated payback periods of three to six years.
There is also substantial wasted heat: the report says the home cannot use more than half the system’s output. An external dry cooler releases excess heat outdoors, particularly during summer.
Heat pumps offer a different proposition. They move heat rather than simply converting electricity into it, delivering roughly 2.5–3 units of heat per unit of electricity, compared with about one unit from a miner.
For a home needing 25,000 kWh of heat annually, SunBit estimated air-source heat-pump operating costs of approximately $1,100, versus $3,170 for district heating. Running a miner only long enough to meet that heat demand produced a modeled $490 surplus after electricity.
The distinction is straightforward: the miner’s financial advantage comes from mining revenue, not superior heating efficiency. Suomi argued that miners maintain heat output in extreme cold, while air-source heat-pump efficiency falls sharply at −25°C. But a heat pump’s economics do not depend on Bitcoin’s price or mining difficulty.
The 2028 problem in the payback period
The report identified the next Bitcoin halving, expected in spring 2028, as the central risk. The block subsidy would fall from 3.125 BTC to 1.5625 BTC—potentially before customers recovered their installation costs.
SunBit’s calculator did not incorporate the halving into its payback estimates. Suomi said the company explained previous halvings and their effects to customers, but did not predict Bitcoin prices or network hash rate and did not guarantee fixed returns.
Holding the model’s other assumptions constant, the report estimated that mining revenue after the halving would fall from about $0.13 to $0.07 per kWh consumed, below the assumed $0.11 electricity price. The resulting net heating cost would be approximately $0.04 per kWh of heat, close to the heat-pump operating cost used in the comparison.
From the report’s November 2026 perspective, winter installers had roughly 18 months before the expected halving. Under its formula, maintaining “free heating” afterward would require Bitcoin at approximately $131,000.
That figure is a conditional model output, not a price forecast. The boiler can keep producing heat without a Bitcoin rally. The promise that mining will pay for it is the speculative part.