MONITOR GAS LEAKS WITH HOMEASSISTANT

Last year I added a magnetic field sensor to my gas meter to monitor gas consumption. The sensor closes when it detects a change in the surrounding magnetic field, and the spinning disc in my gas meter is magnetic at the “0” position, so I know the amount of gas flowing through the meter more-or-less accurately by increasing a counter every time the sensor closes. The setup for that is very simple, first you add a helper to count the gas consumption. Navigate to Settings -> Devices -> Helpers and create a counter entity. The image below is how mine currently looks:

Then create an automation to increase that counter whenever the contact closes:

alias: Gas Meter Hall contact closes
description: ""
trigger:
  - platform: state
    entity_id:
      - switch.gasmeter
    from: "on"
    to: "off"
    for:
      hours: 0
      minutes: 0
      seconds: 5
condition: []
action:
  - service: counter.increment
    data: {}
    target:
      entity_id: counter.gaszahler
mode: single

That’s the simple case to monitor your gas consumption. To check for gas LEAKS I added a second helper entity that holds the current value at 5 minute intervals:

Add an automation to populate that entity every 5 minutes and check if the value is larger than expected. If it is, I send a notification via Jabber:

alias: Check for gas leak
description: ""
trigger: # run every 5 minutes
  - platform: time_pattern
    minutes: /5
condition: []
action:
  - choose:
      - conditions:
          - condition: template # check if the value has increased by more than 15 units
            value_template: >-
              {{ states('counter.gaszahler')|int -
              states('counter.gaszahler_5min_ago')|int > 15 }}
        sequence:
          - service: notify.jabber # send notification via Jabber
            data:
              message: WARNING! Possible Gas Leak!
    default: []
  - service: counter.set_value # set the value of the "5 minute ago" helper to the current value
    data:
      value: "{{states('counter.gaszahler')|int}}"
    target:
      entity_id: counter.gaszahler_5min_ago
mode: single

The biggest issue for me here was getting the information out of my gas meter. I tried a Reed switch first, but the magnetic field of my gas meter was too weak to trigger it. I even considered Jomjol’s AI on the edge for this and it works well on my water meter, but I have no option to mount it in front of my gas meter. The sensor is use now is an “AZDelivery KY-024 hall sensor” that I hotglued to the gasmeter and connected to a spare ESP8266 NodeMCU which sends the sensor state to HomeAssistant via MQTT.

Let me know if you did something similar, I am eager to learn how you monitor your dumb devices for safety issues!

EOF

Category: blog

Tags: HomeAssistant Gas Safety ESP8266 MQTT