How do I build a freeze alert with ESPHome?
Wire a waterproof DS18B20 probe to an ESP32, add ESPHome's one_wire and dallas_temp components, and tape the probe to the pipe. ESPHome only measures; the alert comes from whatever receives the reading, either a Home Assistant automation or an off-site service that the device posts to over HTTPS.
The sensor
Connect the probe's data wire to a GPIO pin with a 4.7kΩ pull-up to 3.3V. With a single probe on the bus you do not need to specify its address. ESPHome reports in °C.
one_wire:
- platform: gpio
pin: GPIO4
sensor:
- platform: dallas_temp
id: pipe_temp_c
name: Garage pipe temperature
update_interval: 60sOption 1: alert from Home Assistant
Once the device is adopted, the sensor appears in Home Assistant and a numeric state automation can notify your phone. This is the quickest route, but the alert depends on Home Assistant and your home internet staying up.
Option 2: post readings off-site
ESPHome's http_request component can POST each reading to a hosted service, which then handles alerts, history, and noticing when the device goes silent. ProbeHarbor publishes a ready-made snippet at probeharbor.dev/esphome/probeharbor.yaml: create a push device, put its ingest URL in secrets.yaml, and point the snippet at your sensor ID.
You can do both: keep the device in Home Assistant for local automations and post to an off-site service for the alerts that have to reach you.
Frequently asked questions
Can ESPHome send a notification by itself?
Not directly to your phone. It can call a Home Assistant action or make an HTTP request, so the notification comes from Home Assistant or from the service receiving the request.
What threshold should the alert use?
34–38°F at the pipe, which is about 1–3°C in ESPHome's units. Use the higher end if it takes you a while to respond.
Related
Get a freeze alert for your space
ProbeHarbor watches probes in garages, crawlspaces, and cabins and alerts you before pipes freeze. The free plan includes email alerts; bring an ESP32 probe or connect Home Assistant.