DIY Grow Chamber – Powered by Pico-Relay-B (All-in-One 8-Channel Control)

[bunkergardenlabs]

Hi everyone,

I recently finished building a small indoor grow chamber using the Pico-Relay-B board — an all-in-one board that combines an MCU with 8 relays.
The chamber is controlled Esphome, and this is the first working prototype (v1.0).

This setup is designed to maintain ideal growing conditions in a compact indoor space. I’m planning to eventually automate it using environmental sensors like temperature, humidity, and CO₂ to help optimize plant health.

I’m documenting this journey as I design and build systems for long-term self-sufficiency.

switch:
  - platform: gpio
    pin: 21
    name: "Relay 1 (CH1)"
  - platform: gpio
    pin: 20
    name: "Relay 2 (CH2)"
  - platform: gpio
    pin: 19
    name: "Relay 3 (CH3)"
  - platform: gpio
    pin: 18
    name: "Relay 4 (CH4)"
  - platform: gpio
    pin: 17
    name: "Relay 5 (CH5)"
  - platform: gpio
    pin: 16
    name: "Relay 6 (CH6)"
  - platform: gpio
    pin: 15
    name: "Relay 7 (CH7)"
  - platform: gpio
    pin: 14
    name: "Relay 8 (CH8)"

For anyone curious about the setup process, there’s a short walkthrough video below.

Experiment Log – Day 1: First Grow Chamber Activation

I’m not an electrical expert, so I kept wiring details minimal in the video. But if you’d like a general reference, here’s a similar board with its wiring diagram:
Industrial 6-Channel ESP32-S3 WiFi Relay Module, Supports WiFi / Bluetooth / RS485 control, Onboard RS485 / Pico HAT interfaces | ESP32-S3-Relay-6CH

The hydroponic port I used is from this Tuya WiFi hydroponics kit:
https://ko.aliexpress.com/item/1005006220525819.html
I designed the chamber to fit both this unit and a small fridge that could accommodate its size.

For the next version, I’m planning to add temperature and humidity sensors to automate the chamber’s power based on environmental conditions.
If you have any ideas or advice on how to approach this, I’d love to hear from you!

By the way, the hydroponic port I used is from this Tuya WiFi hydroponics kit:
https://ko.aliexpress.com/item/1005006220525819.html
I designed the chamber to fit both this unit and a small fridge that could fit its size.

If you have any ideas or advice on how to approach this, I’d love to hear from you!
Since I’m not a native English speaker, I used AI to help translate this post. Please let me know if anything’s unclear

[Flipso (Fli)]

Hey there, thanks for this ultra funny video and your documentation. I would be interested in the box and how you installed ecerything. But keep on doing - thanks for this

[nickrout]

I value your input, and I understand the language difficulties.

However this is not documentation. I have no idea what equipment you are using.

• What is that big fridge like device you are controlling?
• What is your yaml code so far?
• What is your wiring?

[bunkergardenlabs]

Thanks so much for your interest in my project!
By the way, the hydroponic port I used is from this Tuya WiFi hydroponics kit:
https://ko.aliexpress.com/item/1005006220525819.html
I designed the chamber to fit both this unit and a small fridge that could fit its size.

If anything I said isn’t clear or you have more questions, feel free to ask anytime — I’d be happy to explain more.

[bunkergardenlabs]

Thanks a lot for the thoughtful feedback — I really appreciate it!

Let me clarify a few things based on your questions:

1. What is the big fridge-like device?
The chamber is designed to create a stable environment where plants can grow better. It includes temperature, humidity, and (in the future) CO₂ sensors to maintain optimal conditions for plant growth. The fridge-like structure is just a reused mini fridge cabinet — it helps insulate and stabilize the internal environment.

2. YAML code?
I’m currently using ESPHome rather than a Home Assistant YAML automation. Here’s the relay configuration from my ESPHome file:

switch:
  - platform: gpio
    pin: 21
    name: "Relay 1 (CH1)"
  - platform: gpio
    pin: 20
    name: "Relay 2 (CH2)"
  - platform: gpio
    pin: 19
    name: "Relay 3 (CH3)"
  - platform: gpio
    pin: 18
    name: "Relay 4 (CH4)"
  - platform: gpio
    pin: 17
    name: "Relay 5 (CH5)"
  - platform: gpio
    pin: 16
    name: "Relay 6 (CH6)"
  - platform: gpio
    pin: 15
    name: "Relay 7 (CH7)"
  - platform: gpio
    pin: 14
    name: "Relay 8 (CH8)"

3. Wiring?
I briefly showed the wiring setup in the video, but I didn’t go into too much technical detail because I’m not an electrical expert myself. Still, I totally understand your point — here’s a reference diagram for the relay board I used, which might help clarify the wiring:
Industrial 6-Channel ESP32-S3 WiFi Relay Module, Supports WiFi / Bluetooth / RS485 control, Onboard RS485 / Pico HAT interfaces | ESP32-S3-Relay-6CH

[bunkergardenlabs]

Hi, thanks again for taking the time to reply!

Just to clarify—did you mean it’s not considered “documentation” because it’s more of a video record, rather than a written guide?
Or was it mainly due to the lack of technical details (like wiring, parts list, and full code), as mentioned?

Either way, I really appreciate your feedback and I’ll make sure to apply it in future posts!

[nickrout]

No problem.

I really meant, “hey that video is cute, but there’s not a lot of technical info there”.

Now to help further, what is each of those relays supposed to control?

[nickrout]

Also, how are you getting fresh air in there?

You can probably get a temp and humidity sensor connected by just running thin wires past the door seal. There is a recent thread on the forum here about putting sensors in a fridge, if I can find it again I will post a link.

Edit

Fridge / Freezer temp sensors?

I have 2 DS18B20 sensors ready to go into the Fridge / Freezer, the problem is, how do I actually get them in there for a nice clean, permanent installation? Everything seems to be pretty well sealed, can you guys share how you did this? Also, I’m sure there are already sensors built in, is it worth looking at taping into those sensors and integrating? Thanks

[bunkergardenlabs]

@nickrout

No problem.

I really meant, “hey that video is cute, but there’s not a lot of technical info there”.

Now to help further, what is each of those relays supposed to control?

Thanks again for your feedback!

Since I’m not an expert, I avoided going into too much detail in the video—especially for safety reasons.
But it looked like you might be interested in the technical side, so I created a space where I can share more in-depth info and collaborate with others.

I’ve posted the full wiring diagram and will be updating all future projects there as well.

If you’re curious, the instructions for joining are in the video description.
Would love to have you there and continue the conversation!

[bunkergardenlabs]

Ah—thanks for that! Just to clarify: in the video, the “cold air” I mentioned was actually the internal fan circulating air inside the fridge. It’s not pulling in fresh air from outside.

Right now, I’m torn between two options:

1. Drilling a hole with a hole saw to install a small intake fan for fresh air, or
2. Relying on the fact that plants release oxygen during photosynthesis, especially since I’m planning to inject CO₂ into the chamber anyway. If CO₂ levels are controlled, maybe external air isn’t critical?

Still, I want to research this a bit more before deciding.

As for your sensor suggestion—that’s actually one of the options I had in mind!
For the prototype, I plan to run sensor wires through the rubber door seal. Later on, once everything’s finalized, I might drill a proper hole for all sensor connections.

And by the way, the forum thread you linked was super helpful—thank you so much for taking the time