[asaleem89]

I'm simulating hot water storage tank, single-phase, incompressible flow, transient simulation. I need to define an expression that depends on the outlet temperature (areaAve(T)@outlet) at a specific time instant i.e. 3900s (to kick-on the hot water inflow until a certain amount of energy is transferred).

Right now, it keeps the hot water inflow ON way longer than the desired duration, as the solver keeps updating the value of aveArea(T)@outlet at every timestep.

Is there a way that I can use the temperature value at only a specific time instant, at 3900[s]?

[Opaque]

You are basically modeling a thermostat, correct?

Please take a look at the Heating/Ventilation tutorial where the logic for this application is illustrated.