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 8 kW type as an example.
The specification of its efficiency is 85 %:
8000W/0.85=9411.76471W,
9411.76…-8000W=approx. 1412W
1412Wx0.86kcal/h=1214.3kcal/h
Therefore, the heat dissipation will be approx. 1,412 W.
For the efficiency, read the user’s manual – chapter of Specifications.