Dear group members,
Usually in projects, neither designers nor manufacturers provide comprehensive data about Water Heaters. This introduces difficulties when modeling them, especially the EF (Energy Factor or Efficiency Factor, not to be confused with Thermal Efficiency).
Is there an easy way to model Energy Factor for Water Heaters (other than trial-and-error)?
So far, I'm playing with numbers (especially off-cycle (and/or on-cycle) loss coefficient to ambient temperature W/K) to achieve desired EF value.
And is it correct to consider that the only two parameters needed by e+ to find energy consumption for Service Hot Water are the Energy Factor (EF) and the SHW demand flow rate (WaterUse:Equipment/Peak Flow Rate)?
I usually set the peak flow rate to a continuous flow (always on) and convert expected annual service hot water volume consumption to [m3/s] for modeling purposes, then I play with other numbers (power, volume, thermal efficiency, heat loss, ...etc.), if they are not provided by designers, to achieve the designed EF (I do the same for baseline, but I calculate its EF from ASHRAE 90.1 table 7.8).
Is my way to model SHW correct? as EF should represent all parameters related to heater's performance like standby loss and thermal efficiency, by this neutralizing the need to set the actual tank volume/dimensions and heater power, is this correct?
Hisham