diff --git a/changelog-entries/736.md b/changelog-entries/736.md
new file mode 100644
index 000000000..bd4f3b08c
--- /dev/null
+++ b/changelog-entries/736.md
@@ -0,0 +1 @@
+- Added heat-exchanger-simplified to system tests (new suite `heat_exchanger_simplified_test`). Improved Docker and Ubuntu 24.04 compatibility for local system test runs (Compose detection, precice user, build args, CalculiX download).
diff --git a/heat-exchanger-simplified/reference-results/.gitkeep b/heat-exchanger-simplified/reference-results/.gitkeep
new file mode 100644
index 000000000..e69de29bb
diff --git a/tools/tests/components.yaml b/tools/tests/components.yaml
index bd29ba88f..bcb943acd 100644
--- a/tools/tests/components.yaml
+++ b/tools/tests/components.yaml
@@ -117,6 +117,9 @@ calculix-adapter:
     TUTORIALS_REF:
       description: Tutorial git reference to use
       default: "master"
+    PYTHON_BINDINGS_REF:
+      description: Git ref of the Python bindings (required when shared Dockerfile builds python_bindings stage)
+      default: "master"
     CALCULIX_VERSION:
       description: Version of Calculix to use
       default: "2.20"
diff --git a/tools/tests/dockerfiles/ubuntu_2404/Dockerfile b/tools/tests/dockerfiles/ubuntu_2404/Dockerfile
index e87599880..774f13fa4 100644
--- a/tools/tests/dockerfiles/ubuntu_2404/Dockerfile
+++ b/tools/tests/dockerfiles/ubuntu_2404/Dockerfile
@@ -2,13 +2,15 @@ FROM ubuntu:24.04 AS base_image
 USER root
 SHELL ["/bin/bash", "-c"]
 ENV DEBIAN_FRONTEND=noninteractive
-# We set a sensical value, but still have the possibilty to influence this via the build time arguments. 
+# We set a sensical value, but still have the possibilty to influence this via the build time arguments.
 # When the dockerfile is built using the systemtests.py we set the PRECICE_UID and PRECICE_GID to the user executing the systemtests.
 # This ensures no file ownership problems down the line and is the most easy fix, as we normally built the containers locally
 # If not built via the systemtests.py its either possible to specify manually but 1000 would be the default anyway.
+# Ubuntu 24.04+ images include a default user "ubuntu" with UID/GID 1000; remove it so we can create "precice" with the same UID/GID.
 ARG PRECICE_UID=1000
 ARG PRECICE_GID=1000
-RUN groupadd -g ${PRECICE_GID} precice && useradd -u ${PRECICE_UID} -g ${PRECICE_GID} -ms /bin/bash precice
+RUN userdel ubuntu 2>/dev/null || true; groupdel ubuntu 2>/dev/null || true; \
+    groupadd -g ${PRECICE_GID} precice && useradd -u ${PRECICE_UID} -g ${PRECICE_GID} -ms /bin/bash precice
 ENV PATH="${PATH}:/home/precice/.local/bin" 
 ENV LD_LIBRARY_PATH="/home/precice/.local/lib:${LD_LIBRARY_PATH}" 
 ENV CPATH="/home/precice/.local/include:$CPATH"
@@ -83,7 +85,7 @@ RUN git clone https://github.com/precice/openfoam-adapter.git &&\
 
 FROM precice_dependecies AS python_bindings
 COPY --from=precice /home/precice/.local/ /home/precice/.local/
-ARG PYTHON_BINDINGS_REF
+ARG PYTHON_BINDINGS_REF=master
 USER precice
 WORKDIR /home/precice
 # Builds the precice python bindings for python3
@@ -100,7 +102,7 @@ RUN add-apt-repository -y ppa:fenics-packages/fenics && \
     apt-get -qq update && \
     apt-get -qq install --no-install-recommends fenics
 USER precice
-ARG FENICS_ADAPTER_REF
+ARG FENICS_ADAPTER_REF=master
 # Building fenics-adapter
 RUN python3 -m venv --system-site-packages /home/precice/venv && \
     . /home/precice/venv/bin/activate && \
@@ -123,9 +125,9 @@ RUN apt-get -qq update && \
     apt-get -qq install libarpack2-dev libspooles-dev libyaml-cpp-dev
 ARG CALCULIX_VERSION
 USER precice
-#Download Calculix
+#Download Calculix (retry for transient DNS/network)
 WORKDIR /home/precice
-RUN wget http://www.dhondt.de/ccx_${CALCULIX_VERSION}.src.tar.bz2 && \
+RUN wget --tries=3 --retry-connrefused --timeout=30 http://www.dhondt.de/ccx_${CALCULIX_VERSION}.src.tar.bz2 && \
     tar xvjf ccx_${CALCULIX_VERSION}.src.tar.bz2 && \
     rm -fv ccx_${CALCULIX_VERSION}.src.tar.bz2
 
diff --git a/tools/tests/systemtests/Systemtest.py b/tools/tests/systemtests/Systemtest.py
index 6abc5a029..165655e71 100644
--- a/tools/tests/systemtests/Systemtest.py
+++ b/tools/tests/systemtests/Systemtest.py
@@ -22,6 +22,36 @@
 GLOBAL_TIMEOUT = 900
 SHORT_TIMEOUT = 10
 
+# Cached result of docker compose command detection
+_DOCKER_COMPOSE_CMD = None
+
+
+def _get_docker_compose_cmd():
+    """Return the docker compose command list: either ['docker', 'compose'] or ['docker-compose']."""
+    global _DOCKER_COMPOSE_CMD
+    if _DOCKER_COMPOSE_CMD is not None:
+        return _DOCKER_COMPOSE_CMD
+    try:
+        subprocess.run(
+            ['docker', 'compose', 'version'],
+            capture_output=True,
+            timeout=5,
+            check=True,
+        )
+        _DOCKER_COMPOSE_CMD = ['docker', 'compose']
+    except (subprocess.CalledProcessError, FileNotFoundError, subprocess.TimeoutExpired):
+        try:
+            subprocess.run(
+                ['docker-compose', 'version'],
+                capture_output=True,
+                timeout=5,
+                check=True,
+            )
+            _DOCKER_COMPOSE_CMD = ['docker-compose']
+        except (subprocess.CalledProcessError, FileNotFoundError, subprocess.TimeoutExpired):
+            _DOCKER_COMPOSE_CMD = ['docker', 'compose']  # default; will fail with clear error
+    return _DOCKER_COMPOSE_CMD
+
 
 def slugify(value, allow_unicode=False):
     """
@@ -381,13 +411,11 @@ def _run_field_compare(self):
             file.write(docker_compose_content)
         try:
             # Execute docker-compose command
-            process = subprocess.Popen(['docker',
-                                        'compose',
-                                        '--file',
-                                        'docker-compose.field_compare.yaml',
-                                        'up',
-                                        '--exit-code-from',
-                                        'field-compare'],
+            cmd = _get_docker_compose_cmd() + [
+                '-f', 'docker-compose.field_compare.yaml',
+                'up', '--exit-code-from', 'field-compare'
+            ]
+            process = subprocess.Popen(cmd,
                                        stdout=subprocess.PIPE,
                                        stderr=subprocess.PIPE,
                                        start_new_session=True,
@@ -428,11 +456,11 @@ def _build_docker(self):
 
         try:
             # Execute docker-compose command
-            process = subprocess.Popen(['docker',
-                                        'compose',
-                                        '--file',
-                                        'docker-compose.tutorial.yaml',
-                                        'build'],
+            cmd = _get_docker_compose_cmd() + [
+                '-f', 'docker-compose.tutorial.yaml',
+                'build'
+            ]
+            process = subprocess.Popen(cmd,
                                        stdout=subprocess.PIPE,
                                        stderr=subprocess.PIPE,
                                        start_new_session=True,
@@ -472,11 +500,11 @@ def _run_tutorial(self):
         stderr_data = []
         try:
             # Execute docker-compose command
-            process = subprocess.Popen(['docker',
-                                        'compose',
-                                        '--file',
-                                        'docker-compose.tutorial.yaml',
-                                        'up'],
+            cmd = _get_docker_compose_cmd() + [
+                '-f', 'docker-compose.tutorial.yaml',
+                'up'
+            ]
+            process = subprocess.Popen(cmd,
                                        stdout=subprocess.PIPE,
                                        stderr=subprocess.PIPE,
                                        start_new_session=True,
diff --git a/tools/tests/tests.yaml b/tools/tests/tests.yaml
index cc18820ea..d4652abac 100644
--- a/tools/tests/tests.yaml
+++ b/tools/tests/tests.yaml
@@ -88,6 +88,14 @@ test_suites:
           - fluid-cpp
           - solid-python
         reference_result: ./elastic-tube-1d/reference-results/fluid-cpp_solid-python.tar.gz
+  heat_exchanger_simplified_test:
+    tutorials:
+      - path: heat-exchanger-simplified
+        case_combination:
+          - fluid-top-openfoam
+          - fluid-btm-openfoam
+          - solid-calculix
+        reference_result: ./heat-exchanger-simplified/reference-results/fluid-top-openfoam_fluid-btm-openfoam_solid-calculix.tar.gz
   release_test:
     tutorials:
       - path: elastic-tube-1d