The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius. However, The specific heat per gram for water is much higher than that for a metal. For most purposes, it is more meaningful to compare the molar specific heats of substances.
"Heat capacity" (Cp) has dimensional units. "Specific heat" (SH) has no dimensional units. specific heat is the ratio of the heat capacities (Cp at your operating temperature divided by Cp at your base temperature). So, while the specific heat value of water is approximately 1.0 in either the US or SI (or other) systems because it is a ratio having no units, the heat capacity value of water is approximately 4186 J/kg-K in SI units.
All boiler load calculations (steam/water side and gas side) use enthalpies (H), so Cp is seldom seen/used in equations. Q = m x delta H.
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