You can calculate the heat dissipation based on the efficiency of the specification:
output power / efficiency = input power
input power – output power = internal power loss
Then, you can convert the loss to calorie.
Let’s take PCR500LE as an example.
The specification of its efficiency is 54 % (for the input at 100 V):
500 W/0.54 = 926 W
926 W – 500 W = 426 W
426 W x 0.86 kcal/h = 366.36 kcal/h
Therefore, the heat dissipation will be 366.36 kcal/h.
For the efficiency, read the user’s manual – chapter of Specifications.