diff --git a/custom_components/sat/area.py b/custom_components/sat/area.py
index fb3f2a87..58cafd07 100644
--- a/custom_components/sat/area.py
+++ b/custom_components/sat/area.py
@@ -5,7 +5,10 @@
 from homeassistant.const import STATE_UNKNOWN, STATE_UNAVAILABLE
 from homeassistant.core import HomeAssistant, State
 
+from .heating_curve import HeatingCurve
 from .helpers import float_value
+from .pid import PID
+from .pwm import PWM
 from .util import (
     create_pwm_controller,
     create_pid_controller,
@@ -17,13 +20,13 @@
 
 class Area:
     def __init__(self, config_data: MappingProxyType[str, Any], config_options: MappingProxyType[str, Any], entity_id: str):
-        self._hass = None
-        self._entity_id = entity_id
+        self._entity_id: str = entity_id
+        self._hass: HomeAssistant | None = None
 
         # Create controllers with the given configuration options
-        self.pid = create_pid_controller(config_options)
-        self.heating_curve = create_heating_curve_controller(config_data, config_options)
-        self.pwm = create_pwm_controller(self.heating_curve, config_data, config_options)
+        self.pid: PID = create_pid_controller(config_options)
+        self.heating_curve: HeatingCurve = create_heating_curve_controller(config_data, config_options)
+        self.pwm: PWM = create_pwm_controller(self.heating_curve, config_data, config_options)
 
     @property
     def id(self) -> str:
@@ -75,18 +78,20 @@ async def async_added_to_hass(self, hass: HomeAssistant):
 
     async def async_control_heating_loop(self, _time=None) -> None:
         """Asynchronously control the heating loop."""
-        if (temperature_error := self.error) is not None:
-            # Control the integral (if exceeded the time limit)
-            self.pid.update_integral(temperature_error, self.heating_curve.value)
+        if self.error is None or self.heating_curve.value is None:
+            return
+
+        # Control the integral (if exceeded the time limit)
+        self.pid.update_integral(self.error, self.heating_curve.value)
 
 
 class Areas:
-    def __init__(self, config_data: MappingProxyType[str, Any], config_options: MappingProxyType[str, Any], entity_ids: list):
+    def __init__(self, config_data: MappingProxyType[str, Any], config_options: MappingProxyType[str, Any], entity_ids: list[str]):
         """Initialize Areas with multiple Area instances using shared config data and options."""
-        self._entity_ids = entity_ids
-        self._config_data = config_data
-        self._config_options = config_options
-        self._areas = [Area(config_data, config_options, entity_id) for entity_id in entity_ids]
+        self._entity_ids: list[str] = entity_ids
+        self._config_data: MappingProxyType[str, Any] = config_data
+        self._config_options: MappingProxyType[str, Any] = config_options
+        self._areas: list[Area] = [Area(config_data, config_options, entity_id) for entity_id in entity_ids]
 
     @property
     def errors(self) -> List[float]:
diff --git a/custom_components/sat/climate.py b/custom_components/sat/climate.py
index c6295dbf..21d804c0 100644
--- a/custom_components/sat/climate.py
+++ b/custom_components/sat/climate.py
@@ -3,8 +3,9 @@
 
 import asyncio
 import logging
-from datetime import timedelta
+from datetime import timedelta, datetime
 from time import monotonic, time
+from typing import Optional
 
 from homeassistant.components.binary_sensor import DOMAIN as BINARY_SENSOR_DOMAIN
 from homeassistant.components.climate import (
@@ -68,7 +69,7 @@ async def async_setup_entry(_hass: HomeAssistant, _config_entry: ConfigEntry, _a
 
 
 class SatWarmingUp:
-    def __init__(self, error: float, boiler_temperature: float = None, started: int = None):
+    def __init__(self, error: float, boiler_temperature: Optional[float] = None, started: Optional[int] = None):
         self.error = error
         self.boiler_temperature = boiler_temperature
         self.started = started if started is not None else int(time())
@@ -238,7 +239,7 @@ async def async_added_to_hass(self) -> None:
         # Let the coordinator know we are ready
         await self._coordinator.async_added_to_hass()
 
-    async def _register_event_listeners(self, _time=None):
+    async def _register_event_listeners(self, _time: Optional[datetime] = None):
         """Register event listeners."""
         self.async_on_remove(
             async_track_time_interval(
@@ -890,7 +891,7 @@ async def async_track_sensor_temperature(self, entity_id):
 
         self._sensors.append(entity_id)
 
-    async def async_control_heating_loop(self, _time=None) -> None:
+    async def async_control_heating_loop(self, _time: Optional[datetime] = None) -> None:
         """Control the heating based on current temperature, target temperature, and outside temperature."""
         # If the current, target or outside temperature is not available, do nothing
         if self.current_temperature is None or self.target_temperature is None or self.current_outside_temperature is None:
diff --git a/custom_components/sat/config_flow.py b/custom_components/sat/config_flow.py
index 8eec1cc9..68e721d9 100644
--- a/custom_components/sat/config_flow.py
+++ b/custom_components/sat/config_flow.py
@@ -1,7 +1,7 @@
 """Adds config flow for SAT."""
 import asyncio
 import logging
-from typing import Any
+from typing import Optional, Any
 
 import voluptuous as vol
 from homeassistant import config_entries
@@ -25,8 +25,8 @@
 from . import SatDataUpdateCoordinatorFactory
 from .const import *
 from .coordinator import SatDataUpdateCoordinator
-from .manufacturer import ManufacturerFactory, MANUFACTURERS
 from .helpers import calculate_default_maximum_setpoint, snake_case
+from .manufacturer import ManufacturerFactory, MANUFACTURERS
 from .overshoot_protection import OvershootProtection
 from .validators import valid_serial_device
 
@@ -519,7 +519,7 @@ async def async_create_coordinator(self) -> SatDataUpdateCoordinator:
             hass=self.hass, data=self.data, mode=self.data[CONF_MODE], device=self.data[CONF_DEVICE]
         )
 
-    def _create_mqtt_form(self, step_id: str, default_topic: str = None, default_device: str = None):
+    def _create_mqtt_form(self, step_id: str, default_topic: Optional[str] = None, default_device: Optional[str] = None):
         """Create a common MQTT configuration form."""
         schema = {vol.Required(CONF_NAME, default=DEFAULT_NAME): str}
 
diff --git a/custom_components/sat/coordinator.py b/custom_components/sat/coordinator.py
index f9cda253..5d3cac13 100644
--- a/custom_components/sat/coordinator.py
+++ b/custom_components/sat/coordinator.py
@@ -354,7 +354,7 @@ async def async_will_remove_from_hass(self) -> None:
         """Run when an entity is removed from hass."""
         pass
 
-    async def async_control_heating_loop(self, climate: SatClimate = None, _time=None) -> None:
+    async def async_control_heating_loop(self, climate: Optional[SatClimate] = None, _time=None) -> None:
         """Control the heating loop for the device."""
         # Update Flame State
         if not self.flame_active:
diff --git a/custom_components/sat/esphome/__init__.py b/custom_components/sat/esphome/__init__.py
index 2a8585f6..84391d54 100644
--- a/custom_components/sat/esphome/__init__.py
+++ b/custom_components/sat/esphome/__init__.py
@@ -12,6 +12,8 @@
 from homeassistant.components.switch import DOMAIN as SWITCH_DOMAIN, SERVICE_TURN_ON, SERVICE_TURN_OFF
 from homeassistant.core import HomeAssistant, Event
 from homeassistant.helpers import device_registry, entity_registry
+from homeassistant.helpers.device_registry import DeviceEntry
+from homeassistant.helpers.entity_registry import EntityRegistry, RegistryEntry
 from homeassistant.helpers.event import async_track_state_change_event
 
 from ..coordinator import DeviceState, SatDataUpdateCoordinator, SatEntityCoordinator
@@ -47,13 +49,13 @@ class SatEspHomeCoordinator(SatDataUpdateCoordinator, SatEntityCoordinator):
     def __init__(self, hass: HomeAssistant, device_id: str, data: Mapping[str, Any], options: Mapping[str, Any] | None = None) -> None:
         super().__init__(hass, data, options)
 
-        self.data = {}
+        self.data: dict = {}
 
-        self._device = device_registry.async_get(hass).async_get(device_id)
-        self._mac_address = list(self._device.connections)[0][1]
+        self._device: DeviceEntry = device_registry.async_get(hass).async_get(device_id)
+        self._mac_address: str = list(self._device.connections)[0][1]
 
-        self._entity_registry = entity_registry.async_get(hass)
-        self._entities = entity_registry.async_entries_for_device(self._entity_registry, self._device.id)
+        self._entity_registry: EntityRegistry = entity_registry.async_get(hass)
+        self._entities: list[RegistryEntry] = entity_registry.async_entries_for_device(self._entity_registry, self._device.id)
 
     @property
     def device_id(self) -> str:
@@ -113,7 +115,7 @@ def minimum_hot_water_setpoint(self) -> float:
         return super().minimum_hot_water_setpoint
 
     @property
-    def maximum_hot_water_setpoint(self) -> float | None:
+    def maximum_hot_water_setpoint(self) -> float:
         if (setpoint := self.get(SENSOR_DOMAIN, DATA_DHW_SETPOINT_MAXIMUM)) is not None:
             return float(setpoint)
 
diff --git a/custom_components/sat/helpers.py b/custom_components/sat/helpers.py
index eb82acb3..f80fc179 100644
--- a/custom_components/sat/helpers.py
+++ b/custom_components/sat/helpers.py
@@ -24,7 +24,7 @@ def seconds_since(start_time: float | None) -> float:
     return monotonic() - start_time
 
 
-def convert_time_str_to_seconds(time_str: str) -> float:
+def convert_time_str_to_seconds(time_str: str) -> int:
     """
     Convert a time string in the format 'HH:MM:SS' to seconds.
 
@@ -32,11 +32,11 @@ def convert_time_str_to_seconds(time_str: str) -> float:
         time_str: A string representing a time in the format 'HH:MM:SS'.
 
     Returns:
-        float: The time in seconds.
+        int: The time in seconds.
     """
     date_time = dt.parse_time(time_str)
     # Calculate the number of seconds by multiplying the hours, minutes and seconds
-    return (date_time.hour * 3600) + (date_time.minute * 60) + date_time.second
+    return round((date_time.hour * 3600) + (date_time.minute * 60) + date_time.second, 0)
 
 
 def calculate_derivative_per_hour(temperature_error: float, time_taken_seconds: float):
diff --git a/custom_components/sat/mqtt/__init__.py b/custom_components/sat/mqtt/__init__.py
index d1b64e7a..46a023f1 100644
--- a/custom_components/sat/mqtt/__init__.py
+++ b/custom_components/sat/mqtt/__init__.py
@@ -22,10 +22,10 @@ class SatMqttCoordinator(SatDataUpdateCoordinator, ABC):
     def __init__(self, hass: HomeAssistant, device_id: str, data: Mapping[str, Any], options: Mapping[str, Any] | None = None) -> None:
         super().__init__(hass, data, options)
 
-        self.data = {}
-        self._device_id = device_id
-        self._topic = data.get(CONF_MQTT_TOPIC)
-        self._store = Store(hass, STORAGE_VERSION, snake_case(f"{self.__class__.__name__}_{device_id}"))
+        self.data: dict = {}
+        self._device_id: str = device_id
+        self._topic: str = data.get(CONF_MQTT_TOPIC)
+        self._store: Store = Store(hass, STORAGE_VERSION, snake_case(f"{self.__class__.__name__}_{device_id}"))
 
     @property
     def device_id(self) -> str:
diff --git a/custom_components/sat/mqtt/ems.py b/custom_components/sat/mqtt/ems.py
index c7430105..3fd2308a 100644
--- a/custom_components/sat/mqtt/ems.py
+++ b/custom_components/sat/mqtt/ems.py
@@ -100,9 +100,9 @@ def member_id(self) -> int | None:
         # Not supported (yet)
         return None
 
-    async def boot(self) -> SatMqttCoordinator:
+    async def boot(self) -> None:
         # Nothing needs to be booted (yet)
-        return self
+        pass
 
     def get_tracked_entities(self) -> list[str]:
         return [DATA_BOILER_DATA]
diff --git a/custom_components/sat/mqtt/opentherm.py b/custom_components/sat/mqtt/opentherm.py
index cd577f50..1a62a50c 100644
--- a/custom_components/sat/mqtt/opentherm.py
+++ b/custom_components/sat/mqtt/opentherm.py
@@ -86,7 +86,7 @@ def minimum_hot_water_setpoint(self) -> float:
         return super().minimum_hot_water_setpoint
 
     @property
-    def maximum_hot_water_setpoint(self) -> float | None:
+    def maximum_hot_water_setpoint(self) -> float:
         if (setpoint := self.data.get(DATA_DHW_SETPOINT_MAXIMUM)) is not None:
             return float(setpoint)
 
diff --git a/custom_components/sat/overshoot_protection.py b/custom_components/sat/overshoot_protection.py
index 4fd7a38b..8fdda714 100644
--- a/custom_components/sat/overshoot_protection.py
+++ b/custom_components/sat/overshoot_protection.py
@@ -17,10 +17,10 @@
 class OvershootProtection:
     def __init__(self, coordinator: SatDataUpdateCoordinator, heating_system: str):
         """Initialize OvershootProtection with a coordinator and heating system configuration."""
-        self._alpha = 0.5
-        self._coordinator = coordinator
-        self._stable_temperature = None
-        self._setpoint = OVERSHOOT_PROTECTION_SETPOINT.get(heating_system)
+        self._alpha: float = 0.5
+        self._stable_temperature: float | None = None
+        self._coordinator: SatDataUpdateCoordinator = coordinator
+        self._setpoint: int = OVERSHOOT_PROTECTION_SETPOINT.get(heating_system)
 
         if self._setpoint is None:
             raise ValueError(f"Invalid heating system: {heating_system}")
diff --git a/custom_components/sat/pid.py b/custom_components/sat/pid.py
index a75b0c6b..66f0b946 100644
--- a/custom_components/sat/pid.py
+++ b/custom_components/sat/pid.py
@@ -43,38 +43,38 @@ def __init__(self,
         :param sample_time_limit: The minimum time interval between updates to the PID controller, in seconds.
         :param version: The version of math calculation for the controller.
         """
-        self._kp = kp
-        self._ki = ki
-        self._kd = kd
-        self._version = version
-        self._deadband = deadband
-        self._history_size = max_history
-        self._heating_system = heating_system
-        self._automatic_gains = automatic_gains
-        self._automatic_gains_value = automatic_gain_value
-        self._derivative_time_weight = derivative_time_weight
-        self._heating_curve_coefficient = heating_curve_coefficient
-
-        self._last_interval_updated = monotonic()
-        self._sample_time_limit = max(sample_time_limit, 1)
-        self._integral_time_limit = max(integral_time_limit, 1)
+        self._kp: float = kp
+        self._ki: float = ki
+        self._kd: float = kd
+        self._version: int = version
+        self._deadband: float = deadband
+        self._history_size: int = max_history
+        self._heating_system: str = heating_system
+        self._automatic_gains: bool = automatic_gains
+        self._automatic_gains_value: float = automatic_gain_value
+        self._derivative_time_weight: float = derivative_time_weight
+        self._heating_curve_coefficient: float = heating_curve_coefficient
+
+        self._last_interval_updated: float = monotonic()
+        self._sample_time_limit: float = max(sample_time_limit, 1)
+        self._integral_time_limit: float = max(integral_time_limit, 1)
         self.reset()
 
     def reset(self) -> None:
         """Reset the PID controller."""
-        self._last_error = 0.0
-        self._time_elapsed = 0
-        self._last_updated = monotonic()
-        self._last_heating_curve_value = 0
-        self._last_boiler_temperature = None
+        self._last_error: float = 0.0
+        self._time_elapsed: float = 0
+        self._last_updated: float = monotonic()
+        self._last_heating_curve_value: float = 0
+        self._last_boiler_temperature: float | None = None
 
         # Reset the integral and derivative
-        self._integral = 0.0
-        self._raw_derivative = 0.0
+        self._integral: float = 0.0
+        self._raw_derivative: float = 0.0
 
         # Reset all lists
-        self._times = deque(maxlen=self._history_size)
-        self._errors = deque(maxlen=self._history_size)
+        self._times: deque = deque(maxlen=self._history_size)
+        self._errors: deque = deque(maxlen=self._history_size)
 
     def update(self, error: float, heating_curve_value: float, boiler_temperature: float) -> None:
         """Update the PID controller with the current error, inside temperature, outside temperature, and heating curve value.
diff --git a/custom_components/sat/pwm.py b/custom_components/sat/pwm.py
index b127c2ee..7462a299 100644
--- a/custom_components/sat/pwm.py
+++ b/custom_components/sat/pwm.py
@@ -11,6 +11,7 @@
 
 
 class PWMState(str, Enum):
+    """The current state of Pulse Width Modulation"""
     ON = "on"
     OFF = "off"
     IDLE = "idle"
@@ -21,25 +22,25 @@ class PWM:
 
     def __init__(self, heating_curve: HeatingCurve, max_cycle_time: int, automatic_duty_cycle: bool, max_cycles: int, force: bool = False):
         """Initialize the PWM control."""
-        self._alpha = 0.2
-        self._force = force
-        self._last_boiler_temperature = None
+        self._alpha: float = 0.2
+        self._force: bool = force
+        self._last_boiler_temperature: float | None = None
 
-        self._max_cycles = max_cycles
-        self._heating_curve = heating_curve
-        self._max_cycle_time = max_cycle_time
-        self._automatic_duty_cycle = automatic_duty_cycle
+        self._max_cycles: int = max_cycles
+        self._heating_curve: HeatingCurve = heating_curve
+        self._max_cycle_time: int = max_cycle_time
+        self._automatic_duty_cycle: bool = automatic_duty_cycle
 
         # Timing thresholds for duty cycle management
-        self._on_time_lower_threshold = 180
-        self._on_time_upper_threshold = 3600 / self._max_cycles
-        self._on_time_max_threshold = self._on_time_upper_threshold * 2
+        self._on_time_lower_threshold: float = 180
+        self._on_time_upper_threshold: float = 3600 / self._max_cycles
+        self._on_time_max_threshold: float = self._on_time_upper_threshold * 2
 
         # Duty cycle percentage thresholds
-        self._duty_cycle_lower_threshold = self._on_time_lower_threshold / self._on_time_upper_threshold
-        self._duty_cycle_upper_threshold = 1 - self._duty_cycle_lower_threshold
-        self._min_duty_cycle_percentage = self._duty_cycle_lower_threshold / 2
-        self._max_duty_cycle_percentage = 1 - self._min_duty_cycle_percentage
+        self._duty_cycle_lower_threshold: float = self._on_time_lower_threshold / self._on_time_upper_threshold
+        self._duty_cycle_upper_threshold: float = 1 - self._duty_cycle_lower_threshold
+        self._min_duty_cycle_percentage: float = self._duty_cycle_lower_threshold / 2
+        self._max_duty_cycle_percentage: float = 1 - self._min_duty_cycle_percentage
 
         _LOGGER.debug(
             "Initialized PWM control with duty cycle thresholds - Lower: %.2f%%, Upper: %.2f%%",
@@ -50,13 +51,13 @@ def __init__(self, heating_curve: HeatingCurve, max_cycle_time: int, automatic_d
 
     def reset(self) -> None:
         """Reset the PWM control."""
-        self._cycles = 0
-        self._duty_cycle = None
-        self._state = PWMState.IDLE
-        self._last_update = monotonic()
+        self._cycles: int = 0
+        self._state: PWMState = PWMState.IDLE
+        self._last_update: float = monotonic()
+        self._duty_cycle: Tuple[int, int] | None = None
 
-        self._first_duty_cycle_start = None
-        self._last_duty_cycle_percentage = None
+        self._first_duty_cycle_start: float | None = None
+        self._last_duty_cycle_percentage: float | None = None
 
         _LOGGER.info("PWM control reset to initial state.")
 
diff --git a/custom_components/sat/relative_modulation.py b/custom_components/sat/relative_modulation.py
index 1b2d2656..ad77f1e4 100644
--- a/custom_components/sat/relative_modulation.py
+++ b/custom_components/sat/relative_modulation.py
@@ -18,9 +18,9 @@ class RelativeModulationState(str, Enum):
 class RelativeModulation:
     def __init__(self, coordinator: SatDataUpdateCoordinator, heating_system: str):
         """Initialize instance variables"""
-        self._coordinator = coordinator
-        self._heating_system = heating_system
-        self._pulse_width_modulation_enabled = None
+        self._heating_system: str = heating_system
+        self._pulse_width_modulation_enabled: bool = False
+        self._coordinator: SatDataUpdateCoordinator = coordinator
 
         _LOGGER.debug("Relative Modulation initialized for heating system: %s", heating_system)
 
@@ -45,4 +45,4 @@ def state(self) -> RelativeModulationState:
     @property
     def enabled(self) -> bool:
         """Check if the relative modulation is enabled based on its current state"""
-        return self.state != RelativeModulationState.OFF
\ No newline at end of file
+        return self.state != RelativeModulationState.OFF
diff --git a/custom_components/sat/simulator/__init__.py b/custom_components/sat/simulator/__init__.py
index 7d0333ff..8bc884f1 100644
--- a/custom_components/sat/simulator/__init__.py
+++ b/custom_components/sat/simulator/__init__.py
@@ -1,7 +1,8 @@
 from __future__ import annotations
 
+from datetime import datetime
 from time import monotonic
-from typing import TYPE_CHECKING, Mapping, Any
+from typing import Optional, TYPE_CHECKING, Mapping, Any
 
 from homeassistant.core import HomeAssistant
 
@@ -84,7 +85,7 @@ async def async_set_control_max_setpoint(self, value: float) -> None:
         self._maximum_setpoint = value
         await super().async_set_control_max_setpoint(value)
 
-    async def async_control_heating_loop(self, climate: SatClimate = None, _time=None) -> None:
+    async def async_control_heating_loop(self, climate: Optional[SatClimate] = None, _time: Optional[datetime] = None) -> None:
         # Calculate the difference, so we know when to slowdown
         difference = abs(self._boiler_temperature - self.target)
         self.logger.debug(f"Target: {self.target}, Current: {self._boiler_temperature}, Difference: {difference}")
diff --git a/custom_components/sat/switch/__init__.py b/custom_components/sat/switch/__init__.py
index df8bcc8b..a9097b49 100644
--- a/custom_components/sat/switch/__init__.py
+++ b/custom_components/sat/switch/__init__.py
@@ -7,6 +7,7 @@
 from homeassistant.const import SERVICE_TURN_ON, SERVICE_TURN_OFF, ATTR_ENTITY_ID, STATE_ON
 from homeassistant.core import HomeAssistant
 from homeassistant.helpers import entity_registry
+from homeassistant.helpers.entity_registry import RegistryEntry
 
 from ..coordinator import DeviceState, SatDataUpdateCoordinator
 
@@ -21,7 +22,7 @@ def __init__(self, hass: HomeAssistant, entity_id: str, data: Mapping[str, Any],
         """Initialize."""
         super().__init__(hass, data, options)
 
-        self._entity = entity_registry.async_get(hass).async_get(entity_id)
+        self._entity: RegistryEntry = entity_registry.async_get(hass).async_get(entity_id)
 
     @property
     def device_id(self) -> str: