Problem
15,000 kg/h condensate returns at 90°C instead of make-up water at 30°C. cp=4.187.
Formula
Q=m cp ΔT
Solution
=15,000×4.187×60.
Answer
3,768,300 kJ/h or 1,046.75 kW
Engineering check
Verify units, magnitude, assumptions and physical meaning before accepting the result.