Could the excess enthalpy be simply accounted for by the existence of other chemical/phase change reactions not considered in the calculations, particularly important for crystalline compounds releasing energy on heat degradation to amorphous phases? None of these reactions are all that simple, and further wouldn't hydrino energy be released from all hydroxyl-based reactions - making such reactions forming precipitates etc potentially explosive? Which has not been observed.
Mills has known for a long time that too much water quenches hydrino formation. One wants only a small amount of nascent water that hasn't had the opportunity to form van der Waals bonds with other water molecules, so it's at the correct energy to act as a catalyst. So when one looks at his experiments where he feeds in rarified H2 and O2 gases it's in a ballpark ratio of about 50 to 1. Thus little water is formed, and there is relatively lots of H to undergo hydrino reaction. But this is not the case with the mentioned hydroxyl reactions, which generate lots of water which will put a large damper on hydrino formation. Also, hydrino reaction is usually self limiting because of space charge buildup from ionized catalyst. This is why his SunCell utilizes large electrical current - to wipe up that space charge. That's my understanding anyway.