# CLAUDE.md - Development Context for Excess PV Boiler Control

## Project Purpose

This Home Assistant package controls an auxiliary electric heater installed in a DHW (Domestic Hot Water) boiler. It works alongside a heat pump to provide:
- **Preset-based temperature control** with user-adjustable temperatures per preset
- **PV excess utilization** to use surplus solar power instead of exporting
- **Bath boost** with configurable timer for rapid hot water
- **Manual override** for emergency/testing scenarios

## Architecture

```
[Solar Inverter] --> sensor.deye_12_external_ct*_power (3-phase grid power)
                          |
              [binary_sensor.dhw_pv_power_enough_for_aux_heater]
                          |
              [automation: DHW Manage PV Thermostat]
                          |
              [climate.dhw_pv_excess_heating] (shadow thermostat)
                          |
              [binary_sensor.dhw_use_boiler_aux_heater] <-- [manual override]
                          |                              <-- [boost modes]
              [automation: DHW Boiler Heater Relay]
                          |
              [switch.boiler_heater_relay_switch_0] (physical relay)

[input_select.dhw_boiler_preset] --> [automation: DHW Boiler Preset Manager]
[input_number.dhw_boiler_temp_*]          |
                                          v
                                [climate.boiler_temperature] (main thermostat)

[script.dhw_start_bath_boost] --> [timer.bath_time] --> [automation: DHW Bath Time]
[input_number.dhw_bath_boost_duration]                       |
                                                             v
                                              [input_boolean.dhw_bath_boost] + [switch.acm_pump_switch]
```

## Key Entities

### Input Booleans (Modes/Toggles)
| Entity | Purpose |
|--------|---------|
| `input_boolean.dhw_aux_heater_manual_override` | Force heater ON regardless of conditions |
| `input_boolean.dhw_allow_aux_heater_usage` | Master enable for aux heater |
| `input_boolean.dhw_use_excess_pv_for_aux_heater` | Enable PV excess mode |
| `input_boolean.dhw_allow_aux_heater_in_all_modes` | Allow boost in normal thermostat mode |
| `input_boolean.boiler_pv_dummy_heater` | Virtual switch for shadow thermostat |
| `input_boolean.dhw_bath_boost` | Bath boost active flag (managed by automations) |

### Input Select (Presets)
| Entity | Purpose |
|--------|---------|
| `input_select.dhw_boiler_preset` | Active boiler preset: Normal, Eco, Boost, Sleep, Away, Off |

### Timer
| Entity | Purpose |
|--------|---------|
| `timer.bath_time` | Countdown timer for bath boost duration |

### Input Numbers (Thresholds)
| Entity | Purpose | Range |
|--------|---------|-------|
| `input_number.dhw_aux_heater_cut_off_temperature_threshold` | Max temp before heater stops | 50-85°C |
| `input_number.dhw_aux_heater_temperature_threshold` | Hysteresis threshold | 1-15°C |
| `input_number.dhw_pv_target_temperature` | Target temp for PV heating | 40-70°C |
| `input_number.dhw_pv_excess_usage_buffer` | Buffer power before triggering | 0-1000W |
| `input_number.dhw_aux_heater_power` | Heater power rating | 500-9000W |
| `input_number.dhw_pv_excess_usage_start_delay` | Delay before starting PV mode | 1-300s |
| `input_number.dhw_pv_excess_usage_stop_delay` | Delay before stopping PV mode | 1-300s |

### Input Numbers (Preset Temperatures)
| Entity | Purpose | Range |
|--------|---------|-------|
| `input_number.dhw_boiler_temp_normal` | Normal preset target temperature | 30-65°C |
| `input_number.dhw_boiler_temp_eco` | Eco preset target temperature | 30-60°C |
| `input_number.dhw_boiler_temp_boost` | Boost preset target temperature | 40-70°C |
| `input_number.dhw_boiler_temp_sleep` | Sleep preset target temperature | 25-55°C |
| `input_number.dhw_boiler_temp_away` | Away preset target temperature | 20-50°C |
| `input_number.dhw_bath_boost_duration` | Duration for bath boost timer | 5-120 min |

### Scripts
| Entity | Purpose |
|--------|---------|
| `script.dhw_start_bath_boost` | Starts `timer.bath_time` with duration from `dhw_bath_boost_duration` |

### Climate (Generic Thermostats)
| Entity | Purpose |
|--------|---------|
| `climate.dhw_pv_excess_heating` | Shadow thermostat for PV excess mode |
| `climate.boiler_temperature` | Main boiler thermostat (target set by preset manager) |

### Automations
| Entity | Purpose |
|--------|---------|
| `DHW Boiler Heater Relay Automation` | Switches physical relay based on decision sensor |
| `DHW Manage PV Thermostat` | Controls shadow thermostat based on PV availability |
| `DHW Boiler Preset Manager` | Syncs preset selection + temperatures to thermostat, toggles bath boost |
| `DHW Bath Time` | Manages bath boost lifecycle: pump + boost on/off with timer |

### External Entities (Not Defined in Package)
These must exist in your HA instance from other integrations or manual UI setup:

| Entity | Source | Purpose | Fallback if Unavailable |
|--------|--------|---------|------------------------|
| `sensor.boiler_temp` | Heat pump / temperature probe | Boiler water temperature | 100 (prevents running) |
| `sensor.deye_12_external_ct1_power` | Deye inverter integration | Phase 1 grid power (negative = export) | 0 |
| `sensor.deye_12_external_ct2_power` | Deye inverter integration | Phase 2 grid power | 0 |
| `sensor.deye_12_external_ct3_power` | Deye inverter integration | Phase 3 grid power | 0 |
| `sensor.heat_pump_auxiliary_heater` | Heat pump integration | HP aux heater state | treated as 'off' |
| `switch.boiler_heater_relay_switch_0` | Relay device (Shelly, etc.) | Physical heater control | N/A |
| `switch.acm_pump_switch` | Pump relay/smart plug | DHW circulation pump | N/A |
| `switch.schedule_f403a3` | Scheduler integration | Pump schedule to restore after boost | N/A |

## Decision Logic

### binary_sensor.dhw_use_boiler_aux_heater
This is the main decision sensor. It turns ON when:
1. **Manual override** is ON, OR
2. **All conditions met**:
   - Heat pump aux heater is OFF
   - Boiler aux usage is allowed
   - Boiler temp is below cut-off threshold
   - AND one of:
     - PV excess mode active AND shadow thermostat is heating
     - Bath boost active AND main thermostat is heating
     - All-modes boost enabled AND main thermostat is heating

### binary_sensor.dhw_pv_power_enough_for_aux_heater
Determines if there's enough solar export to run the heater:
- **When heater is OFF**: All 3 phases must export > (buffer + heater_power) / 3
- **When heater is ON**: All 3 phases must still be exporting (<=0W import)

### Preset Manager Flow
1. User selects preset from `input_select.dhw_boiler_preset`
2. Automation reads corresponding `input_number.dhw_boiler_temp_<preset>` value
3. Sets `climate.boiler_temperature` to that target + heat mode (or off for "Off" preset)
4. Toggles `input_boolean.dhw_bath_boost` on/off based on whether Boost is selected
5. If user changes a preset temperature input_number, automation re-applies current preset

### Bath Boost Flow
1. User calls `script.dhw_start_bath_boost` (e.g., from a dashboard button)
2. Script starts `timer.bath_time` with duration from `input_number.dhw_bath_boost_duration`
3. `DHW Bath Time` automation detects timer active: turns on pump + bath boost
4. Timer finishes: automation restores pump schedule + turns off boost

## Common Modifications

### Changing Preset Temperatures
Adjust via dashboard sliders at runtime (no YAML edit needed).
The `input_number.dhw_boiler_temp_*` entities store each preset's temperature.

### Adding New Presets
1. Add option to `input_select.dhw_boiler_preset`
2. Add corresponding `input_number.dhw_boiler_temp_<name>` (name must be lowercase match)
3. The preset manager automation uses dynamic entity resolution, so no automation changes needed

### Changing Power Thresholds
Adjust via dashboard at runtime:
- `dhw_pv_excess_usage_buffer`: Increase for more conservative PV triggering
- `dhw_aux_heater_power`: Match to actual heater rating

### Adjusting Timing
Adjust via dashboard at runtime:
- `dhw_pv_excess_usage_start_delay`: Increase to avoid rapid cycling
- `dhw_pv_excess_usage_stop_delay`: Increase to ride through clouds
- `dhw_bath_boost_duration`: Duration of bath boost timer

### Adding New Heating Modes
Edit template section, add new condition in `binary_sensor.dhw_use_boiler_aux_heater` alongside `pv_excess`, `thermostat_activity_boost`, etc.

## Testing/Validation

1. **YAML Syntax**: Run `yamllint *.yaml` or use HA's configuration check
2. **Entity References**: Ensure all `states()` calls reference defined entities
3. **Default Fallbacks**: Verify all `float()` filters have appropriate defaults:
   - Temperature sensors: `float(100)` (fail-safe: heater OFF)
   - Power sensors: `float(0)` (fail-safe: no export detected)
   - Input numbers: `float(<sensible_default>)`

## File Structure

| File | Purpose |
|------|---------|
| `use_excess_pv_in_boiler.yaml` | **Main package file** - install this in HA packages directory |
| `CLAUDE.md` | Development context for AI assistants |
| `README.md` | User-facing documentation |

## Safety Considerations

1. **Never run both heaters**: Template checks `sensor.heat_pump_auxiliary_heater != 'on'`
2. **Temperature cut-off**: Hard limit prevents overheating
3. **Unavailable sensors**: Default to safe values (temp=100, power=0)
4. **Manual override**: Bypasses all checks - use with caution
5. **Bath boost timer**: Auto-disables boost when timer expires