Combined thermal and electricity plants play an essential role in the Russian economy. Steam demand in processing industries is growing rapidly and can be met through increased use of steam boiler capacity. The objective of this paper is to present an approach to primary analysis through a statistical method. The steam boiler is broken down into multiple groups of elements, operating at different temperatures and pressures. For each group, statistical calculations were conducted, and approximations were developed. This approach may be applied where there is insufficient information available.