Can a Bitcoin miner replace a household boiler—and earn enough to pay its electricity bill? SunBit’s installations in Finland show how that can work under favorable mining conditions. But the heating output and the financial return are different propositions: the machine keeps producing heat even when mining no longer covers its running costs.
The report, published on November 9, 2026, describes a 180-square-meter home in Nokia, Finland, that had disconnected from district heating and switched entirely to a SunBit Bitcoin boiler. Its economics depended on Bitcoin’s price, electricity costs and competition across the mining network—not simply on the value of the heat recovered.
How the system works
Mining equipment converts almost all the electricity it consumes into heat. SunBit captures that heat in water at temperatures of up to 60°C, then circulates it through radiators or underfloor heating. The equipment mines Bitcoin while serving as a heat source.
Homeowners buy and own the equipment, pay the electricity bill and retain the Bitcoin mined, subject to applicable fees. Because the machines are noisy, they generally sit in a basement or a separate sound-insulated room.
SunBit CEO and founder Elmeri Suomi told CoinDesk that the company delivered its first production systems in 2025 and had 30 operating installations at the time of the report. All but one were in Finland, replacing or supplementing gas, oil, wood or district heating.
Examples included:
- A first overseas installation in Leekum, the Netherlands, in 2025, replacing gas heating.
- A 200-square-meter home in Kotka, Finland, combining mining equipment with an existing oil boiler.
- An old manor in Tampere, where mining replaced wood heating and maintained a 1,500-liter water tank at 50–60°C.
- A 3,000-square-meter industrial building in Vimpeli, combining mining heat with an air-source heat pump and surplus electricity from a 30-kilowatt solar array.
The report also cited MARA’s recovery of mining heat for Finnish district-heating networks. SunBit’s model instead puts equipment ownership and operating costs directly with the property owner.
The modeled electricity and mining account
SunBit’s calculation for the Nokia home used a Bitmain Antminer S21 XP Hydro running third-party Braiins OS firmware. These were model inputs, not a guaranteed household result:
| Input | SunBit’s assumption |
|---|---|
| Miner hashrate | 495 TH/s |
| Electrical demand | About 5.3 kW |
| Operating schedule | Continuous, year-round |
| Annual electricity consumption | About 46,400 kWh |
| Electricity price | $0.11/kWh |
| Annual electricity bill | Approximately $5,200 in the source’s rounded estimate |
| Bitcoin price | $82,000 |
| Network hashrate | 1,040 EH/s |
| Annual Bitcoin production | Approximately one-twelfth of a BTC |
At those assumptions, the annual Bitcoin output was worth about $6,800 before fees. SunBit put the homeowner’s proceeds after its optional 10% service fee at approximately $6,100, with a further 0.5% mining-pool fee applicable.
The optional service included round-the-clock remote monitoring, operation optimized around Finland’s variable electricity prices and a mobile app. Grid-balancing functionality was planned for later.
Using the source’s rounded figures, mining proceeds after the service fee exceeded electricity costs by about $900 a year. That is an operating surplus, not recovery of the equipment purchase and installation cost. It also does not mean the household can use all the heat produced.
With Bitcoin trading around $81,500 at the time covered by the report, SunBit estimated an electricity-cost break-even Bitcoin price of roughly $70,000 after its service fee. That threshold excluded capital costs and assumed network hashrate stayed unchanged. More competing hashrate would reduce the Bitcoin earned by an individual machine, all else equal.
Observed output was a separate data point
Suomi supplied a mining-pool screenshot from an early customer operating a different machine: a 358 TH/s S21+ Hydro. It showed production of 0.039 BTC over the preceding year, worth approximately $3,160 at the price used in the report.
That installation could replace about 2,000 liters of heating oil annually, according to the account. It should not be treated as validation of the higher-output S21 XP Hydro model: the hardware and reported output were different.
SunBit said it could see data from its initial pilot customers, but later customers used private mining-pool accounts that the company could not access.
Oil savings help; heat pumps set a tougher benchmark
SunBit’s oil-heating comparison assumed a detached house consuming 2,300 liters annually at about $2.19 per liter—roughly $5,000 a year.
Replacing that oil consumption, while generating a modeled mining surplus of about $920 after electricity costs, produced an estimated payback of approximately three and a half years on a quoted installation price of around $20,200. That calculation excluded maintenance, financing interest and additional equipment. The existing oil boiler could remain as backup for the coldest days.
Elsewhere, the report gave an installed-price range of $20,400–$31,400 and estimated payback periods of three to six years. These were projections, not demonstrated returns.
Heat utilization is a major limitation. The report said more than half the heat produced could go unused, with an external fan-equipped dry cooler rejecting the surplus outdoors. This was particularly relevant during southern Finland’s summer, described as running from late May to mid-September. The report contrasted roughly 100 days of winter cold in southwestern Finland with as many as 200 in Lapland.
An air-source heat pump offers a different efficiency profile. The comparison used 2.5–3 kWh of delivered heat per kWh of electricity for a heat pump, against approximately 1 kWh of heat per kWh consumed by a miner.
For a home needing 25,000 kWh of heat annually, SunBit estimated:
- Air-source heat pump: about $1,100 in annual running costs.
- District heating: about $3,170 annually.
- Mining operated only to meet that heat demand: approximately $490 in mining proceeds left after electricity costs, under the modeled conditions.
The miner’s potential advantage therefore came from Bitcoin revenue, not superior heating efficiency. Suomi argued that mining equipment maintained its heat output in severe cold, while air-source heat-pump efficiency could fall sharply at −25°C. Heat-pump operating economics, however, do not depend on Bitcoin’s price or mining difficulty.
The 2028 halving changes the calculation
The central risk was that customers could encounter Bitcoin’s next halving before recovering their installation costs. At the reporting date, the event was expected in spring 2028, reducing the block subsidy from 3.125 BTC to 1.5625 BTC.
SunBit’s calculator used prevailing mining revenue and did not incorporate the halving into its payback estimates. Suomi said the company explained previous halvings to customers but did not forecast Bitcoin prices or network hashrate, or promise fixed returns.
Holding the other modeled conditions constant, the report estimated that mining revenue per kWh consumed would fall from approximately $0.13 to $0.07 after the halving. Against electricity at $0.11/kWh, that would leave a net heating cost of about $0.04 per kWh of heat—described in the report as close to the operating cost of the heat-pump comparison.
For households installing during the winter discussed in the November 2026 report, the remaining period before the expected halving was roughly 18 months. Under the same model, Bitcoin would need to reach approximately $131,000 for mining revenue to continue fully offsetting electricity costs after the halving.
That figure is a conditional break-even estimate, not a price forecast. The operating question is whether mining proceeds and avoided heating purchases can recover the upfront cost before changing network conditions erode the margin.
Source: Original article published by TechFlow, November 9, 2026, at 18:07:09 (UTC+8). The supplied article credits Shaurya Malwa of CoinDesk, with Chinese translation and editing by Chopper of Foresight News.