The idea for Minerkeeper was born in 2021. At the time, I decided to install my own GPU miner at home, but the problem was the heat dissipation and the noise produced by the fans.
Out of curiosity, the miner consisted of 3 Nvidia P104 cards with 8GB of bios-unlocked memory, 1 Nvidia RTX 3060ti card and 1 Nvidia GTX 1080 card. The P104 cards had their fans removed for better airflow.

I then built a support at ceiling level (above the bedroom entrance door) where I could install the miner and be able to use the chimney of an old wood-burning stove to evacuate the heat.

While I was building the stand, I had an idea. In the summer, it’s necessary to vent the heat, but in the winter, it would be really useful to utilize this heat. The hot air coming out of the miner is about 65°C, which is perfect for the winter months.
So I made an iron air valve controlled by a servomotor to direct the flow toward the chimney or inside the house. At this point, I needed a controller and a thermostat to control the valve.

Here you can see the air duct that brings heat back into the house.
The duct that draws air to cool the miner extends almost to the floor, where it finds cooler air (not visible in the photo).

So I started developing what would become the basis of Minerkeeper using an ESP32 board. At the time, I envisioned an LCD display to display some information and to manually adjust the opening or closing of the air valve.

The display was mounted on a standard electrical outlet bracket. You can see the display, a buzzer with alarm functions, and the rotary encoder for navigating the menus.

Since every self-respecting miner cares about energy consumption, I added a meter to keep track of consumption.

Finally, I enclosed the miner with fireproof plasterboard panels, creating a box where the only openings are the cold air intake and the two hot air outlets (towards the chimney and towards the interior of the house).
I lined the internal walls with 6 cm thick rock wool to reduce noise.
As you can see in the photo, the three 120mm fans controlled by Minerkeeper force air through the graphics cards without creating vortices that reduce flow.
Furthermore, by taking air at floor level and expelling it upwards, a natural draft of air is created like in fireplaces… this facilitates the air flow and improves the heat exchange of the video cards.
The photo also shows the temperature probe that measures the air in the miner area. This value is used to monitor the heat and trigger any alarms; in more serious cases (e.g., fire), Minerkeeper shuts down the miner and disconnects the power supply.

The short video shows the air valve and how it works. If Minerkeeper is set to automatic control, it can control the valve based on the house temperature.
When it’s cold, it uses the heat generated by the miner, while when a maximum temperature (user-adjustable) is reached, it sends the heat outside the house.