I deal with steam & condensate applications daily (for over 20 years). While data for lower pressures are right on, when I get into higher pressures / temperatures, I get negative values for most data. The verbiage is also different from what we use in the industry. I assume that “Inner Heat-Steam” is referring to enthalpy of saturated vapor, or “latent heat”. This figure, once again, is accurate with lower pressures, but not at all accurate on higher pressures (still below critical pressures). Wish I had my $5 back. If they could get this right, it would make a nice tool.