The available heat represents the fraction of input energy that remains available for useful work after accounting for exhaust gas temperature, excess air, and combustion air preheat.

\begin{equation}\label{eq:energy-input-exhaust-gas-available-heat-cpp} AH = BH + AC + CAC\end{equation}

Symbols

\(AH\)	Available heat percent \([\unit{ \percent}]\)
\(BH\)	Base heat percentage \([\unit{ \percent}]\)
\(AC\)	Air correction \([\unit{ \percent}]\)
\(CAC\)	Combustion air correction \([\unit{ \percent}]\)