The Core Cost Difference
A conventional quality electric panel heater at 1.1kW costs £80–£200. A 21energy Ofen 2 Pro at the same wattage costs €2,490. That's a premium of approximately £2,100–2,200 to upgrade. The question is whether the Bitcoin earnings justify that premium.
Running Costs Are Identical
This is the crucial point most people miss. A 21energy heater and a conventional heater at the same wattage cost exactly the same to run. Both consume 1.1 kW/h. Your electricity bill is identical. The only difference is that the 21energy device earns Bitcoin while it consumes that electricity. The conventional heater earns nothing.
The Upgrade Premium Analysis
The upgrade premium is ~£2,100. At €808/winter earnings, the premium pays back in roughly 3 winters. After that, you're effectively earning Bitcoin for free on electricity you'd be spending anyway. Over a 10-year product life, the earnings could total ~€8,000 while heating your home every winter.
When NOT to Upgrade
Don't upgrade if: you heat primarily with gas (buy a supplement heater, not a main one), you need the lowest possible upfront cost, or you have significant doubts about Bitcoin's long-term value. The 21energy case requires a long-term Bitcoin positive outlook to make the maths work.
When to Upgrade
Upgrade if: you're buying an electric heater anyway, you hold or are interested in Bitcoin, you have a multi-year horizon, and you want to participate in Bitcoin mining without a dedicated mining setup. For this buyer, the case is compelling.
Sento is the UK ordering point for 21energy products. Prices match the official 21energy website and are updated regularly. Earnings figures are estimates — actual returns vary with Bitcoin price. Not financial advice. Updated March 2026.