Water Heating Time Calculations The specific heat of water is 4.186 J/g°C The equation for calculating the needed energy value for a certain water heating process is: Q=c*m*(dT) c-specific heat (J/g°K) of the heated liquid m- the mass of the liquid that needs to be heated (g) dT- temperature difference during the process (°K) Q- needed amount of energy for the process (J) For example: In order to heat up 200L of water from 45°C to 90°C, we'll use the equation above: Q = 4.186 J/g K *200,000g * 45K = 37,674,000J Conversion of the energy (Q) to power (P): 1 Watt=1 J/s Thus, in order to calculate the time needed for the process (given a heating element of 2000W power) : t(s)=Q/P time=37,674,000J/2000(J/s)=18,837s=313.95min=5.23h=05:14:00 Meaning, it takes about 5 hours to heat up 200L of water from 45°C to 90°C with 2000W heating power. A few examples of the time needed to heat up various volumes of water in different powers: Assumptions: Optimal conditions, no heat is lost to the environment, full conversion of the heating element's voltage into heat. If we were to increase the power twice- the heating time will shorten in half for the same volume, and so on.