The tank charge fraction y is computed as the
5-minute moving average of the following expression:
(∑i (TTani - min(TTanSet)) / (max(TTanSet) - min(TTanSet)) / nTTan - fraUslTan) / (1 - fraUslTan),
where TTani is the measurement from the i-th temperature sensor
along the vertical axis of the tank,
TTanSet are the tank temperature setpoints (two values for each tank cycle),
nTTan is the number of temperature sensors along the vertical axis of the tank,
fraUslTan is the useless fraction of the tank which is computed as
shown in
Buildings.DHC.Plants.Combined.Controls.BaseClasses.ModeCondenserLoop.