CO2 Control

CO2 Control

CO2-based ventilation automation for maintaining healthy indoor air quality.

What is CO2 Control?

The CO2 Control feature monitors carbon dioxide levels in your home and automatically increases ventilation when levels get too high. This helps maintain healthy air quality, especially in bedrooms, offices, and other occupied spaces.

Key Benefits

• Health protection – Prevents dangerous CO2 buildup in enclosed spaces
• Multi-room monitoring – Supports multiple CO2 sensors across different zones
• Automatic ventilation – Increases fan speed when CO2 exceeds thresholds
• Priority control – Takes precedence over Humidity Control when both are active
• Visual feedback – See CO2 levels and control status on the HVAC Fan Card

How It Works

Basic Flow

CO2 Sensors → Threshold Check → Fan Speed Decision → FAN Device

1. CO2 Control reads sensor values from configured CO2 sensors
2. If any sensor exceeds its threshold, CO2 Control requests increased fan speed
3. The fan-speed arbiter processes the request (with priority over Humidity Control)
4. The FAN device increases ventilation to reduce CO2 levels

Priority System

CO2 Control has higher priority than Humidity Control:

• If CO2 is high → Fan speed increases (regardless of humidity)
• If CO2 is normal but humidity is high → Humidity Control manages fan speed
• If both are high → CO2 Control wins (higher priority)

This ensures air quality safety takes precedence over comfort optimization.

Configuration

Enabling CO2 Control

1. Go to Settings → Devices & Services → Ramses Extras
2. Click Configure
3. Enable the CO2 Control feature
4. Select which FAN devices to enable it for

Setting Up CO2 Sensors

CO2 Control supports both built-in and external sensors:

1. Built-in FAN sensor – Use the FAN device's internal CO2 sensor
2. External room sensors – Configure in Sensor Control for zone-based monitoring

Zone-Based CO2 Monitoring

For multi-room setups, configure area sensors in Sensor Control:

area_sensors:
  - area_id: "bedroom"
    co2_entity: "sensor.bedroom_co2"
    zone_id: "bedroom"  # Links to zones configuration
    enabled: true
  
  - area_id: "office"
    co2_entity: "sensor.office_co2"
    zone_id: "office"
    enabled: true

CO2 Control will:

• Monitor each area's CO2 sensor independently
• Trigger ventilation when any area exceeds its threshold
• Open the corresponding zone valve if zones are configured

Threshold Configuration

CO2 Control provides configurable entities:

Entity	Type	Purpose	Default
switch.co2_control_{device_id}	Switch	Enable/disable CO2 control	Off
number.co2_threshold_{device_id}	Number	CO2 trigger level	1000 ppm
number.co2_activation_hysteresis_{device_id}	Number	Buffer above threshold	100 ppm
number.co2_deactivation_hysteresis_{device_id}	Number	Buffer below threshold	100 ppm

Recommended thresholds:

• Bedrooms: 800-1000 ppm
• Offices: 1000-1200 ppm
• Living areas: 1000-1200 ppm

How CO2 Sources Work Together

┌─────────────────────────────────────────────────────────┐
│                  CO2 Control Logic                       │
├─────────────────────────────────────────────────────────┤
│                                                          │
│  Internal CO2 Sensor ──────────┐                         │
│  (FAN device or external)      │                         │
│                                ▼                         │
│  Area Sensors with CO2 ──→  Threshold Check             │
│  (Room-level sensors)      (any source > threshold)     │
│                                │                         │
│                                ▼                         │
│                         Trigger Fan Speed                │
│                                                          │
└─────────────────────────────────────────────────────────┘

• The internal CO2 sensor provides the primary device-level CO2 reading
• Area sensors provide room-specific CO2 levels
• CO2 Control activates if ANY configured source exceeds its threshold
• If a zone is associated with an area sensor, that zone's valve can respond to CO2 demand

CO2 vs Humidity in Area Sensors

An area sensor can monitor:

• Humidity only – For humidity spike detection
• CO2 only – For CO2-based ventilation
• Both – Full room monitoring

Enable the appropriate toggles when configuring the area sensor.

Entities

CO2 Control creates these entities:

Entity	Type	Purpose
switch.co2_control_{device_id}	Switch	Enable/disable CO2 control
number.co2_threshold_{device_id}	Number	CO2 trigger level
number.co2_activation_hysteresis_{device_id}	Number	Buffer above threshold
number.co2_deactivation_hysteresis_{device_id}	Number	Buffer below threshold

CO2 readings come from:

• FAN device's internal sensor (if available)
• External area sensors configured in Sensor Control

Default Threshold Values

• Standard threshold: 1000 ppm
• Range: 400-2000 ppm
• Step: 50 ppm

You can adjust the threshold per device based on your needs:

• Lower (800 ppm) – More sensitive, for sensitive individuals
• Standard (1000 ppm) – Good balance for most homes
• Higher (1200+ ppm) – Less sensitive, for well-ventilated spaces

HVAC Fan Card Integration

The HVAC Fan Card shows CO2 information in the left panel:

┌─────────────────────────┐
│  Indoor Sensor          │
│  Outdoor Sensor         │
│  Remaining Filter       │
├─────────────────────────┤
│  CO2 Sensors:           │
│  ○ Living Room: 650 ppm │
│  ● Bedroom: 1100 ppm    │ ← Active (highlighted)
│  ○ Office: 580 ppm      │
└─────────────────────────┘

• ○ = Normal CO2 level
• ● = High CO2 (threshold exceeded, active)

CO2 Control Button

The top button row includes a CO2 Control toggle:

┌──────┬──────┬──────┬──────┐
│ Fan  │Balance│ CO2  │Settings│
│Speed │      │Control│       │
└──────┴──────┴──────┴──────┘

• On – CO2 Control is active and monitoring sensors
• Off – CO2 Control is disabled, automation will not run

Services

CO2 Control provides these services:

Enable/Disable CO2 Control

service: ramses_extras.enable_co2_control
data:
  device_id: "32:153289"

service: ramses_extras.disable_co2_control
data:
  device_id: "32:153289"

Set Zone Threshold

Set per-zone CO2 thresholds (overrides global threshold):

service: ramses_extras.set_zone_threshold
data:
  device_id: "32:153289"
  zone_id: "bedroom"
  threshold: 800

Trigger CO2 Boost

Manually trigger maximum ventilation:

service: ramses_extras.trigger_co2_boost
data:
  device_id: "32:153289"
  duration_minutes: 30

Automation Coordination

Interaction with Manual Mode

When you press a manual fan speed button on the HVAC Fan Card:

• CO2 Control is temporarily suspended
• The fan stays at your selected speed
• CO2 Control resumes when you press Auto

Interaction with Humidity Control

• If CO2 is high, CO2 Control manages the fan
• If CO2 normalizes, control passes to Humidity Control (if active)
• Both can monitor simultaneously; only one controls at a time

When Extras Automation is Disabled

If you turn off the Auto Toggle on the HVAC Fan Card:

• CO2 Control stops sending fan commands
• Status remains visible but automation is suspended
• CO2 sensors still update and show on the card

Use Cases

Bedrooms

Bedrooms often have high CO2 overnight due to breathing:

• Set threshold to 900-1000 ppm
• Install a CO2 sensor in each bedroom
• CO2 Control ensures fresh air without waking occupants

Home Office

Working from home in a small room:

• Set threshold to 800-900 ppm for alertness
• CO2 Control increases ventilation when concentration drops
• Automatically returns to normal when you leave

Multi-Room Setups

For homes with multiple occupied rooms:

• Configure area sensors for each room
• CO2 Control monitors all rooms simultaneously
• Fan increases when ANY room exceeds threshold

Troubleshooting

"CO2 Control never activates"

Check:

• Is the switch.co2_control_{device_id} turned on?
• Are CO2 sensors configured in Sensor Control?
• Do sensor values actually exceed the threshold?
• Check the HVAC Fan Card – is the CO2 Control button enabled?

"Fan doesn't increase when CO2 is high"

Check:

• Is the device in Manual mode? (CO2 Control is suspended)
• Is transport state showing online?
• Are you using the correct device_id?

Device Native Logic vs Ramses Extras

Important: FAN devices often have their own built-in CO2 control logic. Ramses Extras aims to improve upon this with more sophisticated zone-based control and better integration with other automations.

However, the device's native CO2 logic remains as a fallback:

• When Ramses Extras is active and online, it takes priority
• If your network goes down or Ramses Extras becomes unavailable, the FAN device will fall back to its own built-in CO2 control
• This ensures basic ventilation continues even if Home Assistant or network issues occur

This dual-layer approach provides the best of both worlds: enhanced automation when available, and reliable fallback protection when not.

"CO2 Control not responding"

Check:

• switch.co2_control_{device_id} is enabled
• CO2 sensor entity is available and updating
• Threshold values are appropriate (try lowering to 800 ppm)
• Fan control mode is not manual_override
• Check if CO2 readings are above threshold

"CO2 sensor shows unavailable"

Check:

• Sensor entity exists in Home Assistant
• Sensor is correctly mapped in Sensor Control
• If using an external sensor, verify the entity ID

Best Practices

Sensor Placement

• Place CO2 sensors at breathing height (not on the ceiling)
• Keep away from direct airflow from the ventilation system
• One sensor per enclosed space you want to monitor
• Avoid placing near windows that are frequently opened

Integration with Humidity Control

Both features work well together:

• CO2 Control protects air quality (higher priority)
• Humidity Control manages moisture and comfort
• Configure both for comprehensive automation

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