core/homeassistant/components/weheat/icons.json

{
  "entity": {
    "sensor": {
      "power_output": {
        "default": "mdi:heat-wave"
      },
      "power_input": {
        "default": "mdi:lightning-bolt"
      },
      "cop": {
        "default": "mdi:speedometer"
      }
    }
  }
}