Garage Heater Thermostat

Built for an ESP32

Hardware

• 2 DS18B20 temperature sensors (room sensors - on board and below toolbox)
• 1 MAX6675 thermocouple (exhaust temperature monitoring)
• 3 relays: gas valve, exhaust fan, and blower fan
• OLED display (128x64 SSD1306)
• Rotary encoder for physical controls

Features

• WiFi Web Interface - Control from phone/computer
• OTA Updates - Flash firmware over WiFi
• Adjustable Cycle Times - Tune gas on/off cycles via web UI
• Temperature-Based Safety - Exhaust temp monitoring with automatic cooldown
• Sensor Validation - Detects failed/stuck sensors and shuts down heater
• Watchdog Timer - Auto-recovery from hangs

Safety Limits

• Exhaust Temperature: 140°F max (protects VIVOSUN 6" inline duct fan)
• Room Sensors: 145°F max (protects DS18B20 sensors rated to 150°F)
• Sensor Range: -20°F to 150°F (DS18B20), -40°F to 300°F (thermocouple)

WiFi Setup

If no WiFi credentials are stored, the ESP32 boots in AP mode:

• SSID: garage_heater
• Password: None
• IP Address: 192.168.4.1

Access the web interface to configure WiFi, then system will reboot and connect to your network.

OTA Updates

Network OTA (PlatformIO):

; Add to platformio.ini
upload_protocol = espota
upload_port = Garage-Heater.local
upload_flags = --auth=garage123

Web UI Upload:

1. Navigate to Settings page
2. Upload .bin file
3. System reboots automatically

Build firmware:

pio run --target buildprog
# Binary: .pio/build/nodemcu-32s/firmware.bin

Web Interface

• Main Page: Temperature display, mode controls, setpoint adjustments
• Settings Page: Cycle timing, firmware upload, WiFi configuration

Default Settings

• Gas On Time: 5 minutes
• Gas Rest Time: 1.5 minutes
• High Temp (Occupied): 68°F
• Low Temp (Unoccupied): 38°F