ERV Integration,
Monitoring & Weather Automation

# Python 3.9+ required
pip install esphome

# secrets.yaml — same folder as the ERV yaml, never commit to git
wifi_ssid: "YourSSID"
wifi_password: "YourWiFiPassword"
ota_password: "choose-a-password"
mqtt_user: "erv_monitor"
mqtt_password: "your-mqtt-password"

substitutions:
  device_name: broan-erv-1       # broan-erv-2 for second unit
  mqtt_prefix:  "erv/unit1"       # erv/unit2 for second unit

wifi:
  manual_ip:
    static_ip: 192.168.1.200     # .201 for second unit
    gateway:   192.168.1.1

mqtt:
  broker: 192.168.1.XXX          # your Mosquitto broker IP

# Plug in via USB-C then:
esphome run broan_erv_esphome.yaml

# Watch for these in the logs:
[I] WiFi connected, IP: 192.168.1.200
[I] MQTT connected
[I] Broan ERV: received packet

# If you see alignment/unknown command errors → swap D+/D− wires
# Power-cycle the ERV (breaker) after first ESP32 connection

apt install mosquitto mosquitto-clients

# Create authenticated user:
mosquitto_passwd -c /etc/mosquitto/passwd erv_monitor

# /etc/mosquitto/conf.d/erv.conf
listener 1883
allow_anonymous false
password_file /etc/mosquitto/passwd

systemctl restart mosquitto && systemctl enable mosquitto

# Verify data is flowing from ESP32:
mosquitto_sub -h localhost -u erv_monitor -P yourpassword -t "erv/#" -v
# Should see: erv/unit1/sensor/intake_temperature 68.4

mkdir -p /opt/erv_monitor && cd /opt/erv_monitor
pip install fastapi uvicorn paho-mqtt aiosqlite python-dotenv httpx

# Copy erv_monitor.py and .env.example, then:
cp .env.example .env
nano .env   # set MQTT_BROKER, credentials, DB_PATH

mkdir -p /var/lib/erv_monitor
python erv_monitor.py

# Dashboard available at:
http://your-server-ip:8080

# /etc/systemd/system/erv-monitor.service
[Unit]
Description=ERV Monitor + Automation
After=network.target mosquitto.service

[Service]
WorkingDirectory=/opt/erv_monitor
ExecStart=/usr/bin/python3 erv_monitor.py
Restart=always
RestartSec=5

[Install]
WantedBy=multi-user.target

systemctl daemon-reload && systemctl enable --now erv-monitor

Install Home Assistant OS in its own LXC or VM. Add the official Aqara integration (Settings → Integrations → Aqara). Enable the MQTT integration in HA pointed at your Mosquitto broker. HA republishes every Aqara sensor automatically.

# HA MQTT topic pattern for Aqara sensors:
homeassistant/sensor/aqara_living_room_temp/state
homeassistant/sensor/aqara_bedroom_humidity/state
# Add these topic patterns to ERV_UNITS in erv_monitor.py

# pip install python-aqara  (or use requests directly)
# Aqara developer.aqara.com — create app, get credentials

import httpx, asyncio

async def poll_aqara(mqtt_client):
    # POST to Aqara OpenAPI every 60 seconds
    headers = {"Authorization": f"Bearer {ACCESS_TOKEN}"}
    r = await client.post(
        "https://open-usa.aqara.com/v3.0/open/api",
        json={"intent": "query.resource.value",
              "data": [{"subjectId": DEVICE_ID,
                         "resourceIds": ["4.1.85", "0.1.85"]}]}
              # 4.1.85 = temperature, 0.1.85 = humidity
    )
    for sensor in r.json()["result"]:
        mqtt_client.publish(
            f"aqara/{sensor['subjectId']}/{sensor['resourceId']}",
            sensor["value"]
        )
    await asyncio.sleep(60)

# Requires: SONOFF Zigbee 3.0 USB Dongle Plus (~$20)
# Plug into server. Install Zigbee2MQTT alongside Mosquitto.
# Aqara sensors re-pair to Z2M directly.
# WARNING: test one sensor first — pairing behavior varies.

# Z2M publishes natively to your broker:
zigbee2mqtt/living_room_sensor
# → {"temperature":68.4,"humidity":42,"battery":87}

import httpx

# Eastern PA coordinates — replace with yours
FORECAST_URL = (
    "https://api.open-meteo.com/v1/forecast"
    "?latitude=40.XX&longitude=-75.XX"
    "&hourly=temperature_2m,relativehumidity_2m,"
    "dewpoint_2m,precipitation_probability,windspeed_10m"
    "&forecast_days=2"
    "&temperature_unit=fahrenheit&windspeed_unit=mph"
    "&timezone=America/New_York"
)

async def fetch_forecast() -> dict:
    async with httpx.AsyncClient() as client:
        r = await client.get(FORECAST_URL, timeout=10)
        h = r.json()["hourly"]
        return {
            "outdoor_temp_f":    h["temperature_2m"][0],
            "outdoor_humidity":  h["relativehumidity_2m"][0],
            "dewpoint_f":        h["dewpoint_2m"][0],
            "precip_prob_now":   h["precipitation_probability"][0],
            "temp_in_2h":        h["temperature_2m"][2],
            "temp_in_4h":        h["temperature_2m"][4],
            "temp_in_6h":        h["temperature_2m"][6],
            "temp_in_12h":       h["temperature_2m"][12],
            "temp_in_24h":       h["temperature_2m"][24],
            "humidity_in_4h":    h["relativehumidity_2m"][4],
            "temp_min_12h":      min(h["temperature_2m"][:12]),
            "temp_max_12h":      max(h["temperature_2m"][:12]),
        }

async def weather_poll_loop():
    while True:
        weather = await fetch_forecast()
        # Store in db, publish to MQTT, feed into ERV decision engine
        await record_weather(weather)
        await erv_decision_engine(weather)
        await asyncio.sleep(900)  # poll every 15 minutes

async def erv_decision_engine(weather: dict):
    indoor_rh   = await get_avg_indoor_humidity()   # from Aqara
    outdoor_f   = weather["outdoor_temp_f"]
    outdoor_rh  = weather["outdoor_humidity"]
    temp_in_4h  = weather["temp_in_4h"]

    # Evaluate rules in priority order
    if outdoor_f < 10:
        mode, reason = "Min", "extreme cold"
    elif indoor_rh > 55:
        mode, reason = "Max", "high indoor humidity"
    elif temp_in_4h < outdoor_f - 20:
        mode, reason = "Max", "cold front in 4h — pre-ventilate"
        # Schedule a switch to Min in 3.5 hours
        asyncio.create_task(delayed_mode_set("Min", delay_minutes=210))
    elif outdoor_rh > indoor_rh + 20:
        mode, reason = "Min", "outdoor more humid than indoor"
    elif 45 < outdoor_f < 75 and outdoor_rh < 65:
        mode, reason = "Max", "ideal outdoor conditions"
    elif outdoor_f < 45:
        mode, reason = "Med", "cold — balanced ventilation"
    else:
        mode, reason = "Med", "default"

    for unit_id in ERV_UNITS:
        await set_erv_mode(unit_id, mode, reason)