Sealminer A4 Ultra Hydro
Bitcoin & Bitcoin Cash ASIC Miner
886TH
HASHRATE
9.45W/TH
EFFICIENCY
8373W
POWER
£884.77
EST. MONTHLY
NO PAYBACK
EST. ROI
Image: SunBit · Original source.
Renewables and heat reuse
SunBit identifies Lekkum as its first international project in 2025. A local team installed a Bitcoin Boiler to replace gas heating at a commercial property.
- Project at a glance
- Commercial heating retrofit · 2025
- Source date and context
- 2025 installation, according to operator
- Published financial detail
- The sources reviewed do not include full project accounts.
- Our comparison
- A UK example per 1,000 miner kWh
About 5 minutes to read
SunBit’s first reported installation outside Finland
SunBit identifies Lekkum as its first international project in 2025. Its customer reference describes a Bitcoin Boiler replacing gas heating at a commercial property, installed by a local team. That local installation and support arrangement matters: the property needs reliable heating even while mining income and electricity prices change.
“replaced expensive gas heating”
Replacing gas changes the operating costs
Electricity→liquid-cooled Bitcoin boiler→commercial building heating
The starting point is the cost of keeping the same building comfortable before and after the retrofit. Gas boiler efficiency, the electricity tariff, distribution losses and maintenance all affect the comparison. Retaining mined Bitcoin for a future price rise is a separate decision from whether the heating operation covers its current bills.
What the numbers could look like in the UK
The calculation below uses assumed UK prices to show how the costs fit together. It is our example, not this project’s reported earnings. Replace the inputs with current machine estimates and the costs at your own site.
Illustrative UK calculation
Income and running costs
1,000 kWh used by miners, plus 50 kWh for pumps and fans. All amounts in pounds.
Operating contributionBefore equipment and installation costs
−£9.60−0.96p per miner kWh
This example buys electricity at 12p/kWh and values useful heat at 6p/kWh. These are assumed prices. The heat value should be replaced with the actual cost of the heating you would otherwise use, or the price a customer agrees to pay.
| Mining income | 8p per miner kWh; an assumed rate, not a live earnings estimate |
|---|---|
| Electricity | 12p/kWh × 1,050 kWh = £126.00 |
| Pool fee | 2% of gross mining income |
| Useful heat | 80% of miner electricity = 800 kWh; valued at 6p per delivered kWh |
| Other running costs | £10 per 1,000 miner kWh; an allowance to replace with your own costs |
| Costs still to add | Equipment, installation, finance, tax, depreciation, major replacements and any costs above the allowance |
The contribution is what remains from mining income and useful heat after the stated running costs. It is not net profit: the equipment and other excluded costs still have to be recovered. Pumps and fans use electricity but earn no mining income in this calculation.
| Gross income per miner kWh | Without heat value | With useful heat |
|---|---|---|
| 5p | −£87.00 | −£39.00 |
| 8p Chart example | −£57.60 | −£9.60 |
| 11p | −£28.20 | £19.80 |
- Mining income needed to cover running costs
- 8.98pper miner kWh
- Highest electricity cost or export value supported
- 11.09pper total electricity kWh
These are two ways to read the same example. Adding equipment costs or a larger maintenance allowance raises the income needed and reduces the electricity price the project can afford.
Compare heating options and work out annual costs
Use the heating system you would actually choose as the comparison. For example, a heat pump using electricity at 20p/kWh with a seasonal COP of 3 has an electricity cost of about 6.67p per kWh of heat. A resistance heater at that tariff uses 20p per kWh of heat. These are calculation examples, rather than measurements from this project.
For an annual estimate, use the miner electricity expected during hours when running makes sense. Scale the contribution by annual miner kWh divided by 1,000, then deduct fixed annual costs. Recalculate if electricity prices, mining income or usable heat change.
Simple payback is the total installed cost divided by positive annual cash contribution. There is no payback under a scenario with zero or negative contribution. The sources reviewed here do not provide the full project accounts needed to calculate an actual payback for this installation.
Make the service arrangements part of the design
A local installer and clear service responsibilities matter when integrating specialist computing equipment with an existing heating system.
Gather gas bills from before installation, then electricity and heat readings after installation, alongside occupancy and weather records. Agree who is responsible for maintenance and remote support.
Questions worth asking
- What happens during a mining or internet interruption?
- Does the building remain economical to heat when mining income is low?
Try your own electricity and heat figures
Compare available miners and dated earnings estimates. Include heat only where you can use it or have a customer for it.
Sources and photographs
Sources checked on 29 September 2026. Project facts and quotations come from the publications below; the UK calculations and practical assessment are The Mining Shop’s analysis. This article is based on published material, rather than a site visit.
Photographs: SunBit (source).
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