Ofen 2
(1-year average)
As of 06.2025
(4-year average)
As of 06.2025
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The 21energy Ofen 2 is perfect for you, if you want to heat your home and earn Bitcoin at the same time. Imagine having a heater that not only keeps your home warm, but also provides you with additional income. The Ofen 2 offers a heat output of up to 1,000 watts and can heat rooms up to 50 m². It runs whisper-quiet — under 35 dB on the lowest setting, 40 dB on the medium setting and 45 dB on the highest setting.
Power & ease of use
Heating technology & noise level
Design & mining power
Protection & durability
Mining pool
Operating system
Savings potential
What customers say
5,000+ satisfied customers and trusted by thousands of homes across Europe.
Verified
Awesome Team. Had a great conversation with a customer service agent, helped me understand the inner workings of mining!
Remington Splettstoesser
September 24, 2025
Verified
Sooooo good experience from a french buyer. A customer service really impressive. Perfect and fast communication (thanks Roland!). Will buy again with no doubt.
PBb
November 13, 2024
Verified
very good service ,great pricing fast delivery a seller you can trust
real debrid
April 16, 2025
Verified
Great support and allways answering all Mails!! Very helpful an patiencely even with a Non-Nerd!! Perfect!!!
Stefan Frieg
March 27, 2024
Verified
It was much easier than expected to set up and start mining
Dag Rune Wiksten
November 11, 2024
Verified
Great company and product! A fast response to questions .. It's a great heating solution with cashback in BTC .. the future price of BTC is going up .. so count your blessings in 10 years
Melvin
November 18, 2024
Verified
Top support - lightning fast responses and taking (delayed) delivery date wishes into account. Thanks a ton and keep up the great work!
patrick
January 15, 2025
Verified
Super cool delivery and super cheerful support. A collaboration with our company is conceivable. We look forward to more experiences with you. Thumbs up!
Rene Bobardt
Jul 25, 2024
In the box
Ofen 2
Thermostat
Power cord
Manual
How much you save
The Ofen 2 converts electricity into heat & cashback. You use your energy twice and save money because you can turn off your old heating system.
Electricity costs
You pay for the electricity to run Ofen 2.
Bitcoin cashback
You earn from Bitcoin mining with the Ofen 2.
Heating value
You save when you turn off your existing heating system (gas/oil/heat pump).
How much you save
The Ofen 2 converts electricity into heat & cashback. You use your energy twice and save money because you can turn off your old heating system.
Known from
Efficient by design
Quiet warmth
Whisper-quiet (~35 dB) so it blends into your living room.
Cashback
77 high performance processors turn electricity into warmth and Bitcoin.
Desired temperature
Set your desired temperature and the thermostat maintains it day & night.
Built to last
Premium aluminium for long life and low maintenance.
Touch-safe design
Enclosed heating core and rounded edges, CE certified.
Quiet warmth
Whisper-quiet (~35 dB) so it blends into your living room.
Cashback
77 high performance processors turn electricity into warmth and Bitcoin.
Desired temperature
Set your desired temperature and the thermostat maintains it day & night.
Built to last
Premium aluminium for long life and low maintenance.
Touch-safe design
Enclosed heating core and rounded edges, CE certified.
Made in Austria
See it in action
Which heating saves you the most in {country}?
Austria
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Questions about Ofen 2
Can I operate the Ofen 2 with a LAN cable?
Yes, there is a USB port on the back of the Ofen 2, through which you can connect a LAN cable using a suitable adapter.
How can I control the Ofen 2?
The Ofen 2 can be controlled via the 21energy App. You can turn it on and off, adjust the heating levels, connect it to a thermostat, create schedules, and integrate it into your Home Assistant setup.
Do I need a Bitcoin wallet?
A Bitcoin wallet is required if you want to store the earnings from your mining pool yourself. Alternatively, you can send the earnings directly to an exchange and have them paid out in euros.
How do I receive the mined Bitcoins?
The Bitcoins mined by the Ofen 2 are first credited to your mining pool account. From there, you can transfer them to your Bitcoin wallet or directly to an exchange. More details can be found in the <a href="https://21energy.com/pages/manual" target="_blank">user manual</a>, section 5.4.
Do I need a good internet connection?
The Ofen 2 requires very little bandwidth (<1 Mbit/s). The most important factor is that the connection is stable and reliable.
Can the Ofen 2 be mounted vertically?
This is not recommended by default and should only be done if the Ofen 2 is placed and secured carefully and safely. The wall mount is designed only for horizontal installation.
Good for the environment
The operation of the Ofen 2 can save up to 3 tons of CO₂ per year compared to conventional heaters.
Dive into the specifics
Discover our innovative Bitcoin heaters and find out how it helps you to heat more efficiently and save money.
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