Ofen 2 – 21energy

21energy Ofen 2 - heater & Bitcoin miner in a single device

The 21energy Heater 2 is the ideal solution for anyone who wants to heat their home efficiently and at the same time passively earn Bitcoin. Instead of simply converting electricity into heat, you use it twice: for room heating and for Bitcoin mining.

For a deeper look at the technical and practical possibilities of using miner waste heat, see the book Bitcoin Mining Heat Reuse.

With a heating output of up to 1,000 watts the mining heater is perfect for living rooms, home offices, bedrooms or hobby rooms up to approx. 50 m² - and all that with very quiet operation.

Performance & easy setup (plug & play)

• Heating output: up to 1,000 W - ideal as a supplementary or full heater depending on room size and insulation
• Easy installation: plug & play - simply plug in, connect, get started
• Quick setup: Wi-Fi connectivity and initial setup via the 21energy app in just a few minutes
• User-friendliness: includes an instruction manual and video tutorial, easy to understand even for less technically experienced users

You don't need deep technical or mining knowledge: the Ofen 2 is designed to be set up as simply as possible and used in everyday life.

Heating technology & noise - pleasant warmth, whisper-quiet operation

The 21energy Ofen 2 uses a combination of convection and radiant heat to heat the room evenly:

• Convection heat: heats the room air gently and evenly
• Radiant heat: provides a particularly cosy feeling of warmth near the heater

Despite integrated mining hardware, the heater stays very quiet:

• approx. < 35 dB on the lowest setting
• approx. 40 dB on the medium setting
• approx. < 45 dB at 1,000 watts (highest setting)

This makes the mining heater suitable even for living spaces or home offices where a quiet environment is important.

Design & mining performance - aesthetics meet hashrate

The Ofen 2 combines modern design with strong mining performance:

• Material: high-quality materials and powder-coated steel
• Appearance: plain, timeless design that blends discreetly into many living styles
• Robustness: stable, durable construction
• Size: 90 x 32 x 14 cm
• Weight: 24 kg

Mining performance:

• Hashrate: up to 40 TH/s
• Efficiency: up to 20 J/TH

This gives the Ofen 2 an impressive Bitcoin mining performancethat also serves as a heat source—making better use of the electricity consumed for heating.

Protection, filters & durability

To keep your mining heater running reliably for a long time, it is equipped with several protective mechanisms:

• Air and dust filters protect the internal hardware from contamination
• Longer lifespan thanks to less dust build-up inside the device
• Galvanised sheet metal ensures corrosion protection and robustness in various environments

This means the Ofen 2 can also be used in more demanding spaces while maintaining a long service life.

Mining pools & solo mining

The integrated Bitcoin miner is compatible with various mining pools and is also suitable for Solo mining:

• support for various Bitcoin mining pools
• Optional Solo mining for users who want to go their own way
• For solo mining, the Blitzpool is recommended

This lets you choose the mining strategy that best suits your personal setup and risk appetite.

Operating system: Braiins OS+ for more efficiency

The Ofen 2 uses the specially optimised Braiins OS+ for improved efficiency:

• auto-tuning function for automatic optimisation of the mining parameters
• Up to 20% higher efficiency and up to 20% higher hashrate at the same power consumption (manufacturer's specification)
• Better cash flow thanks to optimised mining performance

This way you use the electricity you put in as efficiently as possible and increase the potential of your Bitcoin returns.

What’s included

The package includes:

• 1× 21energy Ofen 2 (mining heater)
• 1× thermostat (connection via Bluetooth)
• 1× power cable (1 metre)
• 1× manual
• A standard base is always included.

So you have everything you need to get started, right in the box.

Who is the 21energy Ofen 2 for?

The mining heater is ideal if you:

• heat with electricity anyway or are looking for an electric supplementary heater
• are interested in Bitcoin and mining
• want to partly offset your heating costs through mining income
• value quiet operation, ease of use and a smart design

With the 21energy Ofen 2, you turn heating costs into a chance for additional Bitcoin returns - efficient, quiet and conveniently controllable via app and thermostat.