diff --git a/aioecowitt/sensor.py b/aioecowitt/sensor.py
index 3df5da2..cd57261 100644
--- a/aioecowitt/sensor.py
+++ b/aioecowitt/sensor.py
@@ -459,4 +459,5 @@ class EcoWittMapping:
     ),
     "runtime": EcoWittMapping("Runtime", EcoWittSensorTypes.INTERNAL),
     "interval": EcoWittMapping("Interval", EcoWittSensorTypes.INTERNAL),
+    "heap": EcoWittMapping("Memory heap", EcoWittSensorTypes.INTERNAL),
 }
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..82f16ea
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,19 @@
+import pytest
+
+from aioecowitt import server
+
+
+@pytest.fixture
+def ecowitt_server():
+    """EcoWitt server fixture."""
+    ecowitt_server = server.EcoWittListener()
+    yield ecowitt_server
+
+
+@pytest.fixture
+def ecowitt_http(event_loop, aiohttp_raw_server, aiohttp_client, ecowitt_server):
+    """EcoWitt HTTP fixture."""
+    raw_server = event_loop.run_until_complete(
+        aiohttp_raw_server(ecowitt_server.handler)
+    )
+    return event_loop.run_until_complete(aiohttp_client(raw_server))
diff --git a/tests/const.py b/tests/const.py
index 47f052b..e83d525 100644
--- a/tests/const.py
+++ b/tests/const.py
@@ -60,3 +60,36 @@
     "freq": "868M",
     "model": "GW2000A",
 }
+
+GW2000A_V3_DATA = {
+    "PASSKEY": "345544D8EAF42E1B8824A86D8250D5A3",
+    "stationtype": "GW2000A_V3.1.0",
+    "runtime": "158060",
+    "heap": "124256",
+    "dateutc": "2024-02-08 10: 36: 28",
+    "tempinf": "69.44",
+    "humidityin": "36",
+    "baromrelin": "26.175",
+    "baromabsin": "26.175",
+    "tempf": "64.76",
+    "humidity": "48",
+    "winddir": "293",
+    "windspeedmph": "0.00",
+    "windgustmph": "0.00",
+    "maxdailygust": "1.34",
+    "solarradiation": "3.87",
+    "uv": "0",
+    "rrain_piezo": "0.000",
+    "erain_piezo": "0.000",
+    "hrain_piezo": "0.000",
+    "drain_piezo": "0.000",
+    "wrain_piezo": "0.000",
+    "mrain_piezo": "0.000",
+    "yrain_piezo": "0.000",
+    "ws90cap_volt": "1.3",
+    "ws90_ver": "133",
+    "wh90batt": "2.90",
+    "freq": "868M",
+    "model": "GW2000A",
+    "interval": "60",
+}
diff --git a/tests/test_sensor.py b/tests/test_sensor.py
index f4477b2..8300e9a 100644
--- a/tests/test_sensor.py
+++ b/tests/test_sensor.py
@@ -1,5 +1,9 @@
 """Test ecowitt sensor module."""
+import pytest
 
+from aioecowitt import server
+
+from .const import GW2000A_V3_DATA
 from aioecowitt import sensor
 
 
@@ -27,3 +31,25 @@ def on_change() -> None:
 
     ecowit_sensor.update_value(11, 0, 0)
     assert called
+
+
+@pytest.mark.asyncio
+async def test_heap_field(ecowitt_server, ecowitt_http) -> None:
+    """Test handling of heap field."""
+    heap_sensor = None
+
+    def on_change(sensor: server.EcoWittSensor) -> None:
+        """Test callback."""
+        if sensor.key == "heap":
+            nonlocal heap_sensor
+            heap_sensor = sensor
+
+    ecowitt_server.new_sensor_cb.append(on_change)
+
+    resp = await ecowitt_http.post("/", data=GW2000A_V3_DATA)
+    assert resp.status == 200
+    text = await resp.text()
+    assert text == "OK"
+
+    assert heap_sensor
+    assert heap_sensor.value == GW2000A_V3_DATA["heap"]
diff --git a/tests/test_server.py b/tests/test_server.py
index 38365ce..39e70e8 100644
--- a/tests/test_server.py
+++ b/tests/test_server.py
@@ -9,22 +9,6 @@
 # pylint: disable=redefined-outer-name
 
 
-@pytest.fixture
-def ecowitt_server():
-    """EcoWitt server fixture."""
-    ecowitt_server = server.EcoWittListener()
-    yield ecowitt_server
-
-
-@pytest.fixture
-def ecowitt_http(event_loop, aiohttp_raw_server, aiohttp_client, ecowitt_server):
-    """EcoWitt HTTP fixture."""
-    raw_server = event_loop.run_until_complete(
-        aiohttp_raw_server(ecowitt_server.handler)
-    )
-    return event_loop.run_until_complete(aiohttp_client(raw_server))
-
-
 @pytest.mark.asyncio
 async def test_server_start(ecowitt_server, ecowitt_http) -> None:
     """Test server start."""