Subscribe to mqtt topic

Configuration
1

Hi

For a few hours i have been trying to subscribe to an mqtt topic.

configuration.yaml

mqtt:
  sensor:
    - name: "flow_temp_c"
      state_topic: "emon/PoolHeatMeter"
      unique_id: "phm_flow_temp_c"
      device:
        name: "Pool Heat Meter"
        identifiers:
          - "phm"

When i go to the gui of HA, under “Pool Heat Meter debug info”

i see:

Instantaneous value: '2025-10-23T14:55:00'
Value during error state: '2000-01-01T00:00:00'
error_flags: 67108864
instantaneous_value: -11917
energy_kwh: 15
volume_m3: 1562.323
power_w: 0
flow_m3h: 0.983
flow_temp_c: 28.6
return_temp_c: 28.66
delta_temp_c: -0.06
timestamp_local: 2025-10-23T13:57:05+0100
host: PoolHusRaspberryPI

But the value of “flow_temp_c” is unknown,

What am i missing?

2

i was missing; value_template: “{{ value_json.flow_temp_c }}”

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