diff --git a/custom_components/dreo/pydreo/pydreoheater.py b/custom_components/dreo/pydreo/pydreoheater.py
index 14c8d93..81c3e1f 100644
--- a/custom_components/dreo/pydreo/pydreoheater.py
+++ b/custom_components/dreo/pydreo/pydreoheater.py
@@ -173,6 +173,7 @@ def preset_mode(self, level: str) -> None:
             _LOGGER.error("Preset mode %s is not in the acceptable list: %s",
                             level,
                             self._device_definition.preset_modes)
+            raise ValueError(f"preset_mode must be one of: {self.preset_modes}")
 
     @mode.setter
     def mode(self, mode: str) -> None:
@@ -224,7 +225,8 @@ def oscon(self, value: bool) -> None:
             self._send_command(OSCON_KEY, value)
         else:
             _LOGGER.error("Attempting to set oscillation on on a device that doesn't support it.")
-            return
+            raise ValueError(f"Attempting to set oscillation on on a device that doesn't support it.")
+        return
 
     @property
     def oscangle(self) -> HeaterOscillationAngles:
diff --git a/tests/pydreo/api_responses/get_device_state_HSH004S_1.json b/tests/pydreo/api_responses/get_device_state_HSH004S_1.json
new file mode 100644
index 0000000..f9dbb9c
--- /dev/null
+++ b/tests/pydreo/api_responses/get_device_state_HSH004S_1.json
@@ -0,0 +1,153 @@
+{
+  "code": 0,
+  "msg": "OK",
+  "data": {
+    "currentPage": 1,
+    "pageSize": 100,
+    "totalNum": 2,
+    "totalPage": 1,
+    "familyRooms": null,
+    "list": [
+      {
+        "deviceId": "4456",
+        "sn": "HSH004S_1",
+        "brand": "Dreo",
+        "model": "DR-HSH004S",
+        "productId": "1536529638074978306",
+        "productName": "Heater",
+        "deviceName": "Heater 1",
+        "shared": false,
+        "series": null,
+        "seriesName": "Atom One S",
+        "type": 0,
+        "owner": true,
+        "familyId": null,
+        "familyName": null,
+        "roomId": null,
+        "roomName": null,
+        "roomNameI18Key": "",
+        "color": "b",
+        "controlsConf": {
+          "template": "DR-HSH004S",
+          "lottie": {
+            "key": "poweron",
+            "frames": [
+              {
+                "value": 0,
+                "frame": [
+                  0
+                ]
+              },
+              {
+                "value": 1,
+                "frame": [
+                  2
+                ]
+              }
+            ]
+          },
+          "instructions": {
+            "en": "https://fe.dreo.com/en/safety-protection-instructions/",
+            "zh": "https://fe.dreo.com/zh/safety-protection-instructions/"
+          },
+          "cards": [
+            {
+              "type": 2,
+              "title": "device_control_temp",
+              "icon": "",
+              "image": "",
+              "url": "",
+              "show": true
+            },
+            {
+              "type": 6,
+              "title": "device_settings_title",
+              "icon": "ic_setting",
+              "image": "",
+              "url": "dreo://nav/device/setting?deviceSn=${sn}",
+              "show": true,
+              "key": "setting"
+            }
+          ],
+          "preference": [
+            {
+              "id": "200",
+              "type": "Panel Sound",
+              "title": "device_control_panelsound",
+              "image": "ic_mute",
+              "reverse": true,
+              "cmd": "muteon"
+            },
+            {
+              "id": "210",
+              "type": "Display Auto Off",
+              "title": "device_fans_mode_auto_display",
+              "image": "ic_display",
+              "reverse": true,
+              "cmd": "lighton"
+            },
+            {
+              "id": "220",
+              "type": "Child Lock",
+              "title": "device_control_childlock",
+              "image": "ic_child_lock",
+              "reverse": false,
+              "cmd": "childlockon"
+            },
+            {
+              "id": "230",
+              "type": "Temperature Unit",
+              "title": "device_control_temp_unit",
+              "image": "ic_temp_unit"
+            },
+            {
+              "id": "240",
+              "type": "Temperature Calibration",
+              "title": "device_control_temp_calibration",
+              "image": "ic_temp_cal"
+            }
+          ],
+          "control": [
+            {
+              "swingtype": false,
+              "hideSafeMode": false
+            }
+          ],
+          "category": "Space Heater"
+        },
+        "mainConf": {
+          "isSmart": true,
+          "isWifi": true,
+          "isBluetooth": true,
+          "isVoiceControl": true
+        },
+        "resourcesConf": {
+          "imageSmallSrc": "https://resources.dreo-cloud.com/app/preSigned202406/285c6f0e219a6f40b5a2b79a053cf6d3cb.png",
+          "imageFullSrc": "https://resources.dreo-cloud.com/app/preSigned202406/288eb1e27a155b4b4c875393b04313706a.zip",
+          "imageSmallDarkSrc": "",
+          "imageFullDarkSrc": ""
+        },
+        "servicesConf": [
+          {
+            "key": "user_manual",
+            "value": "https://resources.dreo-cloud.com/app/202310/12056ea09c80d5455f9aa4e713ca8bd84e.pdf"
+          }
+        ],
+        "userManuals": [
+          {
+            "url": "https://resources.dreo-cloud.com/app/preSigned202407/2b5ae671ab4f64b05a03cb3d4ba3527b4.pdf",
+            "icon": null,
+            "desc": "Smart PTC Fan Heater (US)",
+            "lang": "en"
+          },
+          {
+            "url": "https://resources.dreo-cloud.com/app/preSigned202407/24bc6a0c439f348ca9a73d5108a82c9be.pdf",
+            "icon": null,
+            "desc": "Smart PTC Fan Heater (EU)",
+            "lang": "en"
+          }
+        ]
+      }
+    ]
+  }
+}
diff --git a/tests/pydreo/test_pydreoheater.py b/tests/pydreo/test_pydreoheater.py
new file mode 100644
index 0000000..8650287
--- /dev/null
+++ b/tests/pydreo/test_pydreoheater.py
@@ -0,0 +1,48 @@
+"""Tests for Dreo Fans"""
+# pylint: disable=used-before-assignment
+import logging
+from typing import TYPE_CHECKING
+from unittest.mock import patch, call
+import pytest
+
+if TYPE_CHECKING:
+    from  .imports import * # pylint: disable=W0401,W0614
+    from . import call_json
+    from .testbase import TestBase
+else:
+    from imports import * # pylint: disable=W0401,W0614
+    import call_json
+    from testbase import TestBase
+
+logger = logging.getLogger(__name__)
+logger.setLevel(logging.DEBUG)
+
+LOGIN_RESPONSE = call_json.LOGIN_RET_BODY
+
+
+class TestPyDreoHeater(TestBase):
+    """Test PyDreoHeater class."""
+    def test_heater_load_and_send_commands(self):
+        """Load heater and test sending commands."""
+
+        self.get_devices_file_name = "get_device_state_HSH004S_1.json"
+        self.manager.load_devices()
+        assert len(self.manager.heaters) == 1
+        heater = self.manager.heaters[0]
+
+        assert heater.heat_range == (1, 3)
+        assert heater.preset_modes == ['H1', 'H2', 'H3']
+
+        with patch('pydreo.PyDreo.send_command') as mock_send_command:
+            heater.poweron = True
+            mock_send_command.assert_called_once_with(heater, {POWERON_KEY: True})
+
+        with (patch('pydreo.PyDreo.send_command') as mock_send_command):
+            heater.preset_mode = 'H1'
+            mock_send_command.assert_has_calls([call(heater, {HTALEVEL_KEY: 1})], True)
+
+        with pytest.raises(ValueError):
+            heater.preset_mode = 'not_a_mode'
+
+
+