When modeling cooling towers, it is very important that you input the tower parameters accurately since the CBECC simulation is very sensitive to these inputs. A message such as this may appear in the LOG file.
2016-Dec-05 19:19:43 – 1: Autosizing of cooling tower UA failed for tower XXXX
2016-Dec-05 19:19:43 – EnergyPlus Severe Error(s) (1):
2016-Dec-05 19:19:43 – 1: Bad starting values for UA
Review the following parameters on the cooling tower for accuracy as it relates to the load served by the tower.
Tower Tonnage (In the case of a chiller, this generally should be about 20% more than the chiller tonnage)
Tower Setpoint (we suggest 80 degrees)
Tower Fan Airflow (we suggest 200 cfm/ton)
Condenser Water Flow Rate (It is very important this is consistent with the tower tonnage, very low or very high gpm/ton flows here cause problems, so typically 3 gpm/ton)
Careful and accurate input of these parameters will ensure a successful simulation of the tower.
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