# Water heating energy and recovery
# Scope: Well-mixed water heating; constant heat capacity and efficiency.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

volume = 50 L
density = 1000 kg/m^3
heatCapacity = 4200 J/(kg*K)
rise = 40 K
power = 2000 W
efficiency = 0.9

energy := volume*density*heatCapacity*rise [kWh]
duration := energy/(power*efficiency) [s]

check heat-up time budget: duration <= 5400.0 s

scenario alternative: volume = 40 L