Home Assistant: Maintenance reminders using NFC tags

There are places where NFC tags can be very useful and one of those is possibly a cleanup reminder! I have Mitsubishi Heat pump which filters should be vacuumed once a month as recommended by the manufacturer. The problem here is, I never ever remember when was the last time I actually did it! So, how about Home Assistant and NFC tags to keep track of it? Let’s think of a following sequence:

1. Vacuum the filters
2. Tap phone next to the heat pump NFC tag to reset cleanup timer
3. Get notified when a month has passed since last cleanup

Quite useful right? Of course you could create automation to manually click an entity on Home Assistant using app or web browser, but I think a NFC sticker works here quite well.

Creating NFC tag

NFC tags can be programmed just by using Home Assistant Companion App (iOS or Android) and a programmable NFC sticker. To write your tag using the companion app can be done by navigating the app to Settings -> Tags -> + Add New -> Fill in the info -> Create and Write.

After writing you should get a TAG ID that can then be used in an automation. So store the ID in a text file for a while and then paste it to the automation later.

Now just stick the NFC sticker on the side of selected device.

Automation

For this automation we need three items: input_datetime to keep the date of our ‘last cleaned’ status, template sensor to convert this date time to ‘last cleaned‘ days and finally an automation to set the last cleaned date into the input_datetime defined previously.

Here’s my package:

input_datetime:
  heat_pump_filter_last_cleaned:
    name: Heat Pump filter last cleaned
    has_time: false
    has_date: true

template:
  -  sensor:
      - name: "Heat Pump filter cleanup in days"
        unique_id: heat_pump_filter_clean
        icon: "mdi:wrench-clock"
        state: >
          {%- set cycle = (this.attributes.get('clean_cycle_days', 30) | int) -%}
          {%- set due =  strptime(states('input_datetime.heat_pump_filter_last_cleaned'), '%Y-%m-%d' ) + timedelta(days = cycle) -%}
          {{ ((as_timestamp(due) - as_timestamp(now())) | int /60/1440) | round(0) }}
        attributes:
          clean_cycle_days: 30 # Cycle amount in days

automation:
  - id: 'maintenance_set_heatpump_filter_last_cleaned'
    description: "Maintenance: Reset heat pump filter last cleaned"
    trigger:
    - platform: tag
      tag_id: f1892138-fe90-442e-8d0b-d1cc356e5d13 # Tag id
    condition: []
    action:
    - service: input_datetime.set_datetime
      data:
        datetime: '{{ now() }}'
      target:
        entity_id: input_datetime.heat_pump_filter_last_cleaned
    mode: single

The configurable variable here is the cycle_clean_days that contains the clean cycle in days and tag_id that is responsible of resetting the cycle when scanned.