History & Evolution of BrewPi Hardware

Consistent fermentation temperature is one of the most important factors in producing great beer. Even small fluctuations can produce off-flavors, stalled fermentations, or inconsistent results batch to batch. BrewPi solves this by continuously monitoring your wort temperature and adjusting heating and cooling to follow a precise temperature profile — whether that's a simple static temperature or a complex multi-day ramp for a lager.

Fundamentally, a BrewPi temperature controller consists of:

• Some way to turn on and off heating/cooling
• Some way to measure the temperature of your beer/fridge/chamber
• A microcontroller to receive the temperature readings, interpret them, and toggle heating/cooling on and off
• A power source for all of the above

Historically, this was implemented using an Arduino as the microcontroller, hard-wired DS18B20 temperature sensors, and relays for heating and cooling. Power was provided by a serial cable hooked up to a Raspberry Pi (hence the name BrewPi!). Unfortunately, this meant that your temperature controller had to be physically tethered to the Raspberry Pi, and building a controller required a lot of soldering.

Arduino to ESP8266 to ESP32

The BrewPi-ESP project took the BrewPi control algorithm and reimplemented it — first on an ESP8266, and now on an ESP32. With each step in this evolution, the options for how to build a controller grew and the number of cables required shrank.

The ESP8266 (typically a LoLin D1 Mini) was the first wireless BrewPi, replacing the serial cable with WiFi. It's no longer recommended for new builds due to ongoing framework issues that may prevent future firmware updates.

The ESP32-S2 (LoLin S2 Mini) is pin-compatible with the D1 Mini, making it a drop-in replacement. However, it lacks Bluetooth, so it can't support Inkbird wireless temperature sensors or Tilt Hydrometers.

The ESP32 (LoLin D32 or D32 Pro) is the recommended choice for all new builds. Its dual-core processor with both WiFi and Bluetooth enables every feature: TFT color displays, Inkbird Bluetooth temperature sensors, Tilt Hydrometer integration, and TP-Link Kasa WiFi smart plugs.

What This Means for You

With the ESP32, you now have the option to:

• Replace the USB cable tethering your controller to a Raspberry Pi with WiFi
• Replace hard-wired DS18B20 temperature sensors with Bluetooth Inkbird sensors
• Replace physically connected relays and mains wiring with TP-Link Kasa WiFi smart plugs

These added choices mean more freedom for you, the brewer — but they also make deciding what hardware to use more difficult. That's where this guide comes in. The sections below walk through each build approach so you can choose the one that fits your skills, budget, and brewing setup.

Solder-Free BrewPi-ESP Build

By combining the ESP32's WiFi and Bluetooth capabilities with off-the-shelf smart home hardware, you can build a fully functional BrewPi without soldering a single wire — or directly interact with line voltage. This is the fastest path to a working temperature controller.

How It Works

Instead of hard-wired components, a solder-free build replaces each piece with a wireless alternative:

• Temperature sensing — Inkbird Bluetooth thermometers (such as the IBS-TH1 or IBS-TH2) or a Tilt Hydrometer replace wired DS18B20 sensors. The ESP32 reads them over Bluetooth.
• Heating/cooling control — TP-Link Kasa WiFi smart plugs replace physical relays. Your heating and cooling devices simply plug into the smart plugs, and the ESP32 toggles them on and off over WiFi.
• The controller itself — A bare ESP32 board (LoLin D32 or D32 Pro) powered by a USB cable. No PCB, no case required. With the D32 Pro you can even optionally add a screen by just snapping in a cable.

You flash the firmware, connect everything to your WiFi network, configure the devices, and you're controlling fermentation temperatures.

Advantages

• No soldering, no wiring — Completely off-the-shelf components with no electrical work needed
• Fastest build — Can be set up in under an hour once you have the parts
• No enclosure needed — No relays or mains wiring means no need for an electrical project box
• Easiest to get started — Great option if you want to try BrewPi before committing to a more involved build

Disadvantages

• Battery-dependent sensors — Inkbird sensors and Tilt Hydrometers run on batteries. If a battery dies mid-fermentation, the controller loses its temperature readings
• WiFi-dependent control — If your WiFi network goes down, the ESP32 can't toggle the Kasa smart plugs. Your heating/cooling will remain in whatever state it was last set to
• Higher cost — Inkbird sensors ($25 each) and Kasa smart plugs ($15 each) add up compared to the wired alternatives, and batteries need periodic replacement

BrewPi-ESP "All-in-One" PCB

If you're comfortable with some soldering the "All-in-One" PCB design integrates everything onto a single board: the two-channel relay for controlling heating and cooling, an onboard AC-to-DC power supply, connectors for the ESP32 microcontroller, a TFT display header, and an RJ45 jack for temperature sensors. You solder the board, mount your ESP32, plug in your sensors and display, wire mains power in and switched power out, and you're done.

These PCBs can be purchased largely preassembled, meaning that the only soldering you will need to do is of the DS18b20 temperature sensors and pins onto the ESP32 controller -- and you're welcome to mix in "solder free" alternatives as you see fit.

What You'll Need

• All-in-One PCB — available fully assembled from Tindie or can be purchased from a PCB fab house using the available design files
• LoLin D32 or D32 Pro — the ESP32 board that plugs directly into the PCB headers
• Temperature sensors — DS18B20 sensors connected to a separate sensor breakout board, which is then connected via a standard ethernet cable to the onboard RJ45 jack
• TFT display (optional) — the LoLin TFT 2.4" color display connects to the D32 Pro with a ribbon cable, or a generic LCD screen can be used with a D32 instead
• Enclosure — a project box to house the assembled board - 3D printable design files are available
• AC power cord and outlets — for mains input and switched heating/cooling outputs

Advantages

• Minimal internal wiring — relays, power supply, and signal routing are all handled by the PCB itself, so there are very few loose wires inside your enclosure
• Most compact build — everything on one board means the smallest possible enclosure
• Integrated power supply — the onboard AC-to-DC converter provides clean, reliable 5V power without a separate power brick
• Clean, professional result — the finished build looks and feels polished

Disadvantages

• Less modular — if a relay or the power supply fails, the entire board may need to be replaced rather than swapping out a single component
• Soldering required — the board requires soldering surface-mount and through-hole components (or you can purchase a pre-assembled board)

Build with a "One Size Fits Most" ESP32 PCB

The "One Size Fits Most" PCB is a modular design that connects your ESP32 to separate, off-the-shelf relay boards, power supplies, and temperature sensors using dupont jumper cables. It's the closest in spirit to the original Arduino-based BrewPi builds — each component is distinct, individually replaceable, and wired together inside an enclosure.

What You'll Need

• "One Size" PCB — available from Tindie or custom PCB fabrication using provided design fles
• LoLin D32 or D32 Pro — this ESP32-based board plugs into the 16-pin headers on the PCB
• 2-channel 5V relay board — a standard off-the-shelf relay module, connected to the PCB with dupont cables
• 5V 2A power supply module — a separate AC-to-DC power supply, also connected with dupont cables
• Temperature sensors — DS18B20 sensors connected via a standard ethernet cable to the onboard RJ45 jack (a separate sensor breakout board is also needed)
• Display (optional) — supports either a full-color TFT display or the classic LCD2004 monochrome display. LCD2004 support requires soldering SMD components on the PCB
• Enclosure — a project box large enough to house the PCB, relay board, and power supply separately

The PCB itself can be assembled with through-hole components only which greatly simplifies soldering, or with SMD components (required for LCD2004 display support).

Advantages

• Fully modular — if a relay burns out or a power supply dies, you replace just that component, not the whole board
• Flexible display options — choose between a color TFT or the classic LCD2004 monochrome display
• Closest to the classic BrewPi — if you've built a BrewPi before, this design will feel familiar
• Through-hole assembly option — can be built without SMD soldering if you don't need LCD2004 support

Disadvantages

• Most internal wiring — the separate components all need to be connected with jumper cables, which means more wires inside your enclosure
• Larger enclosure needed — the PCB, relay board, and power supply are all separate pieces that need to fit inside your project box
• More assembly steps — connecting all the dupont cables takes more time and care than the all-in-one approach

Building without a PCB

There is no requirement to use a purpose-built PCB — a BrewPi-ESP can be built entirely on a breadboard or with point-to-point wiring. The ESP32 pins for relays, temperature sensors, and displays are documented in the firmware, so you can wire everything up directly.

Although we don't (currently) cover this in a tutorial on this site, this is also the path to take if you want to use a different ESP32 development board than the LoLin D32/D32 Pro, or if you want to design a fully custom setup.

What You'll Need

This build requires many of the same discrete components as the "one size" build, but you will be using a breadboard/perfboard for connecting everything together rather than the PCB.

• Any ESP32 development board — the LoLin D32/D32 Pro are recommended, but any ESP32-WROOM or ESP32-WROVER board will work as long as you map the correct pins
• Breadboard or perfboard — for prototyping or a more permanent build
• Relay module — a standard 5V relay board for switching heating/cooling
• DS18B20 temperature sensors — with a 4.7kΩ pull-up resistor on the data line
• 5V AC-to-DC power supply — to power the ESP32 and relay board
• Jumper wires — male-to-female and male-to-male for making all the connections
• Display (optional) — an LCD2004 or TFT display, wired according to the firmware pin definitions

Advantages

• Maximum flexibility — choose any ESP32 board, any relay, any layout. Nothing is locked to a specific PCB design
• No PCB ordering and minimal soldering — a breadboard build only requires that pins be soldered to the ESP32 controller, making it a good option for prototyping or testing before committing to a PCB build
• Cheapest option — if you already have a breadboard and jumper wires, the component cost can be very low

Disadvantages

• Most wiring and complexity — every connection between the ESP32, relays, sensors, and display must be wired by hand, with no PCB routing to guide you
• Less reliable long-term — breadboard connections can loosen over time, especially in environments with vibration (e.g., next to a chest freezer compressor)
• No standard enclosure — without a PCB to mount, fitting everything neatly into a project box takes more creativity
• More room for error — incorrect wiring can damage components, and troubleshooting a rats-nest of jumper wires is harder than tracing a PCB layout

Which Build is Right for You?

Still Not Sure? Start Here

• Just want to try BrewPi? Go solder-free. You can be up and running in under an hour with no tools, and upgrade to a PCB build later if you want.
• Want a clean, permanent build with minimal fuss? The all-in-one PCB gives you the most polished result with the least internal wiring. Buy one pre-assembled from Tindie and you'll barely need to touch a soldering iron.
• Want full control over every component? The one-size PCB keeps everything modular and replaceable — closest to the classic BrewPi experience.
• Have your own ideas? Build without a PCB. It's the most flexible option, and a great way to prototype before committing to a board.

Remember — these options aren't mutually exclusive. Every PCB-based build can use wireless Inkbird sensors or Kasa smart plugs in place of (or alongside) wired sensors and relays. Start with whatever gets you brewing, and upgrade from there.