Then increase pressure fast to a working level. At this moment excess heat will appear.
Here's an interesting graph from my recent testing. Note that the temperature rises rapidly each time H is added to a de-loaded cell. This illustrates that the loading of H into Pd is exothermic, a well-known behavior. It's also interesting that the neutron count seems to peak whenever this happens. The increase isn't much and needs further analysis of the data to confirm, but it seems repeatable in this case.