To deliver the same amount of energy, the flowrate of hot water will have to be 45 times than that of steam necessitating higher pumping costs. Use steam in place of hot water where ever possible.
Steam is one of the most widely used media to convey heat over distances. Because steam flows in response to the pressure drop along the line, expensive circulating pumps are not needed. However this is not the case with other heating media like hot water and high temperature oils.
The specific heat capacity of a fluid is the amount of heat that can be carried along by the fluid. The specific heat capacity of hot water is 1kcal/kg degC while that of steam is 540kcal/kg.Thus to achieve the same heat transfer, the flowrate of hot water will be much more than that of steam. Higher flow rate in case of hot water requires larger pipes and higher pumping costs.
Overall, the lower capital and running costs of steam generation, distribution and condensate return systems has lead to many users choosing to install new steam systems in preference to other energy media, such as gas fired, hot water, and electric and thermal oil systems.
The table below gives the comparison between Steam and hot water as a heating media