Types of claimed XHs and possible causes of error
In the present discussion about the possible errors contained in the F&P paper to ICCF3 (1), it often happens that different sources of error are mixed up. To avoid the resulting misunderstandings, it's useful first to identified the different types of excess heat claimed by F&P, which are affected by completely different source of errors.
Although F&P, and the researchers who endorsed their claims, postulated the existence of a single nuclear effect, the FPE (*), which should have been the cause of any reported anomalous manifestation (excess heat (XH) or nuclear radiation), a more careful analysis of the HX anomalies suggests that they derive from different artifacts depending on the mathematical models used to analyze the experimental data, or even from a wrong determination of these data. The mathematical models and the experimental data used by F&P and their replicators are not uniform, but varies in accordance to the experimental regime, as better clarified by Lonchampt in paragraph 3.3 of his ICCF6 paper (2). Therefore, in analyzing these source of errors, it is essential to distinguish the various regimes or phases which onset during the F&P open cell tests and the type of excess heat claimed in each of them.
The following jpeg should clarify the situation:
By putting together the (a) and (b) regimes identified by Lonchampt (for which the same relation is used, neglecting only one term for the first regime), the following 3 types of excess heat can be identified:
1) LXH - the Low-level eXcess Heat (about 1 W) that F&P claimed to occur during the entire run of their test until the cell temperature remains quite far from the boiling point. This LXH derives from the complicated mathematical model used by F&P to determine a single heat transfer coefficient k (see, for instance, equation  in (1)) which should take into account all heat losses at different temperatures and times. Consequently, this approach results in calibration problems due to neglecting or miscalculation of various possible side effects, such as partial recombination, droplet entrainment, etc., as has been pointed out by various authors long ago, for example Wilson (3), Morrison (4) and Shanahan (5);
2) HXH – the High-level eXcess Heat (hundreds of W) that F&P have claimed to happen when the cell is allowed to boil-off to dryness. This HXH derives from a totally different path than LXH. Mathematics is also different. In (1), the HXH math is applied in the "CALCULATION" section on page 16, in which the equations are different from those shown in the section in which F&P explained their "Method of Data Evaluation" used to calculate the LXH. However, in the HXH case the error is not in the equations, but in the input data, which are completely out of the reality. F&P assumed that half of the initial water (i.e. 2.5 moles = 45 cm3) vaporized in just 10 minutes (600 s), but in reality the water evaporated in a much longer period, lasting several hours. F&P supported their wrong assumption by showing in their videos the rapid decrease of the foam at the end of the boiling period of each cell, assuming that it was rapidly evaporating water (6). Even if not explicitly stated, F&P have hinted that this HXH was produced in all the 4 cells of the experiment described in (1);
3) HAD – Heat After Dead events have been claimed by F&P to have occurred many times, but it has been documented only for one cell in the experiment described in paper (1). More specifically, they claimed that it happened after the conclusion of the boil-off phase of Cell 2 because, as shown in Figure 8, the cell temperature remained at the boiling point for about 3 hours after the presumed opening of the circuit due to the complete dryness of the cell. It's not clear which error led to this wrong claim, but, as already shown (7), a useful hint comes from the observation that during the 3 hours of presumed HAD the electric circuit was not open at all, as indicated by the voltage, which remained above zero for all that period.
(*) It should be taken into account that the real FPE is considered to be associated with power densities greater than 1000 W/cm3, which have been claimed by F&P only in the 4 cell experiment, as said in the preface of the ICCF3 paper (1): "We present here one aspect of our recent research on the calorimetry of the Pd/D2O system which has been concerned with high rates of specific excess enthalpy generation (> 1kWcm-3) at temperatures close to (or at) the boiling point of the electrolyte solution." This power density was calculated in 3700 W/cm3 on page 16, so it refers to the HXH only.