We have just installed a new HYDAC power unit and it seems to be running very hot.

This is a common occurrence during a new installation/setup on a machine. As the installation process is worked through, the motor has most likely been running for much longer times or more frequent cycles than what the machine's normal working cycle will be. This happens because relief valves are being adjusted, flow controls may need adjustment, and even curiosity with a new piece of equipment can cause the run time to be longer than what the actual everyday work cycle will be. After installation, run a simulation of the actual application to see if heat is still a problem.