21energy Reviews 

1,193
•
TrustScore 5 out of 5

4.8

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Rated 5 out of 5 stars

The description matches the device parameters, it works without issues. Delivery was fast and packaging really good.

Rated 5 out of 5 stars

Everyone should have one of these! The divice is well manufactured solid and just fits in every interior, no question. The team is extremely reachable and responsive. Even an non-technical but adm... See more

Rated 5 out of 5 stars

A refurbished miner bought several months ago showed problems and stalled. 21energy - after reaching out to them by email - showed an amazing service, professionalism and remotely helped nail the... See more

Rated 5 out of 5 stars

Cannot be easier to get it up and running ! The app (iOS) is well made and feels intuitive, the heater itself is very quiet even when running at its maximum power. I have using it for 5 days now a... See more

Company details

  1. Thermal Energy Company

About 21energy

Written by the company

21energy Ofen 3 – Bitcoin Heater
Buy "Ofen 3"
Discover all Bitcoin Heaters

About 21energy

21energy develops & distributes innovative heating systems based on high-performance computers, the so-called Bitcoin Miner: here, the electricity energy is converted into both heat and income through the so-called "mining" of Bitcoins.

In this way, 21energy customers "earn money with heating" & effectively save heating costs and, when switching from oil or gas, a correspondingly large amount of carbon dioxide.

The entire value creation process, from development to production and sales, takes place in Tyrol, Austria. Founded in October 2022, the start-up has already sold about 1,000 units of its world-leading heating system across Europe.


Contact info

4.8

Excellent

TrustScore 5 out of 5

1K reviews

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Replied to 100% of negative reviews

Typically replies within 48 hours

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4.8

All reviews

(1,193)

461 reviews in the last 12 months

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Rated 3 out of 5 stars

It is the second time I order from 21…

It is the second time I order from 21 energy. Both time the chipmunk had been damaged. The first time a board had unsocketed itself. This time two fan connector wires had been bent 45 degrees and I had to solder the wires onto the circuit board.

First time I complained about the order. Nothing productive came out of it and I ended up debugging the issue myself. This second time I did not even bother but just carried out the repair on my own.

August 6, 2025
21energy logo

Reply from 21energy

Hello David,

thank you for your review, even though it is unfortunately not entirely positive.

I will write to you directly to discuss the situation and hope that we can find a suitable solution for you.

Thank you and best regards
Roland

Rated 5 out of 5 stars

Really fantastic end-to-end service

Really fantastic end-to-end service; from pre-order, order, tracking, delivery, packaging and installation, 21energy are a top class outfit. They're quick to respond to any queries, always professional and courteous and critically, they manufacture a first rate product - wouldn't hesitate to recommend.

April 15, 2025
Unprompted review
Rated 5 out of 5 stars

Outstanding Customer Support – A Company That Truly Cares

Initially, my experience with 21energy started off quite poorly due to some serious issues with my order. However, I must say that the way they handled the situation has completely changed my opinion.

I was deeply impressed by their dedication and commitment to resolving the problems I encountered. In particular, Roland, one of the company's owners, deserves special recognition. His care, attention to detail, and genuine concern for customer satisfaction are remarkable.

In Roland’s hands, you can feel confident that you're dealing with someone who truly values their customers. Even if an issue arises — as can happen with any business — their kindness, cordiality, and extreme willingness to find a solution make all the difference.

I believe this level of customer care is rare, and for that reason, I can now recommend 21energy with confidence. Mistakes can happen, but when a company shows such dedication to making things right, it's clear that they stand behind their products and their customers.

March 3, 2025
Unprompted review
Rated 5 out of 5 stars

Experience with 21Energy

Serious company that responds very quickly to your questions and your problems. I have been an international buyer (China, Europe and USA) for more than 20 years in the industrial world and I guarantee that 21enegy is a reliable supplier. I understand that there may be doubts about purchasing second-hand products but 21Energy will support you in this process. Order processing in less than 48 hours. Questions answered in less than 2 hours. TOP supplier.

February 4, 2025
Rated 5 out of 5 stars

Top support

Top support - lightning fast responses and taking (delayed) delivery date wishes into account.

Thanks a ton and keep up the great work!

January 15, 2025
Rated 5 out of 5 stars

Great company and product

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

November 18, 2024
Rated 5 out of 5 stars

Excellent customer service

Excellent customer service. Energy21 allowed me the opportunity to visit them on site to view the Ofen Pro in person and afforded me time to understand the product more fully and patiently answering all my questions. Additionally, on line any questions I asked were answered fully and promptly.

December 4, 2024
Rated 5 out of 5 stars

Everyone should have one of these!

Everyone should have one of these!
The divice is well manufactured solid and just fits in every interior, no question.
The team is extremely reachable and responsive. Even an non-technical but administrative request from my side was solved the next day. Just perfect!
Average 17-18 Kwh/day and 1900 SATS/day = 110 SAT/kWh

November 24, 2024

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