diff --git a/homeassistant/components/incomfort/water_heater.py b/homeassistant/components/incomfort/water_heater.py
index 28424069d1c..e7620ac2a1a 100644
--- a/homeassistant/components/incomfort/water_heater.py
+++ b/homeassistant/components/incomfort/water_heater.py
@@ -54,12 +54,16 @@ class IncomfortWaterHeater(IncomfortBoilerEntity, WaterHeaterEntity):
         return {k: v for k, v in self._heater.status.items() if k in HEATER_ATTRS}
 
     @property
-    def current_temperature(self) -> float:
+    def current_temperature(self) -> float | None:
         """Return the current temperature."""
         if self._heater.is_tapping:
             return self._heater.tap_temp
         if self._heater.is_pumping:
             return self._heater.heater_temp
+        if self._heater.heater_temp is None:
+            return self._heater.tap_temp
+        if self._heater.tap_temp is None:
+            return self._heater.heater_temp
         return max(self._heater.heater_temp, self._heater.tap_temp)
 
     @property
diff --git a/tests/components/incomfort/test_water_heater.py b/tests/components/incomfort/test_water_heater.py
index 5b7aebc50a8..082aecf6d49 100644
--- a/tests/components/incomfort/test_water_heater.py
+++ b/tests/components/incomfort/test_water_heater.py
@@ -2,6 +2,7 @@
 
 from unittest.mock import MagicMock, patch
 
+import pytest
 from syrupy import SnapshotAssertion
 
 from homeassistant.config_entries import ConfigEntry
@@ -9,6 +10,8 @@ from homeassistant.const import Platform
 from homeassistant.core import HomeAssistant
 from homeassistant.helpers import entity_registry as er
 
+from .conftest import MOCK_HEATER_STATUS
+
 from tests.common import snapshot_platform
 
 
@@ -23,3 +26,44 @@ async def test_setup_platform(
     """Test the incomfort entities are set up correctly."""
     await hass.config_entries.async_setup(mock_config_entry.entry_id)
     await snapshot_platform(hass, entity_registry, snapshot, mock_config_entry.entry_id)
+
+
+@pytest.mark.parametrize(
+    ("mock_heater_status", "current_temperature"),
+    [
+        (MOCK_HEATER_STATUS, 35.3),
+        (MOCK_HEATER_STATUS | {"is_tapping": True}, 30.2),
+        (MOCK_HEATER_STATUS | {"is_pumping": True}, 35.3),
+        (MOCK_HEATER_STATUS | {"heater_temp": None}, 30.2),
+        (MOCK_HEATER_STATUS | {"tap_temp": None}, 35.3),
+        (MOCK_HEATER_STATUS | {"heater_temp": None, "tap_temp": None}, None),
+    ],
+    ids=[
+        "both_temps_available_choose_highest",
+        "is_tapping_choose_tapping_temp",
+        "is_pumping_choose_heater_temp",
+        "heater_temp_not_available_choose_tapping_temp",
+        "tapping_temp_not_available_choose_heater_temp",
+        "tapping_and_heater_temp_not_available_unknown",
+    ],
+)
+@patch("homeassistant.components.incomfort.PLATFORMS", [Platform.WATER_HEATER])
+async def test_current_temperature_cases(
+    hass: HomeAssistant,
+    mock_incomfort: MagicMock,
+    entity_registry: er.EntityRegistry,
+    mock_config_entry: ConfigEntry,
+    current_temperature: float | None,
+) -> None:
+    """Test incomfort entities with alternate current temperature calculation.
+
+    The boilers current temperature is calculated from the testdata:
+    heater_temp: 35.34
+    tap_temp: 30.21
+
+    It is based on the operating mode as the boiler can heat tap water or
+    the house.
+    """
+    await hass.config_entries.async_setup(mock_config_entry.entry_id)
+    assert (state := hass.states.get("water_heater.boiler")) is not None
+    assert state.attributes.get("current_temperature") == current_temperature