The calibration and validation of a model for predicting the performance of gas-fired tankless water heaters in domestic hot water applications

The model predictions were validated against data emanating from a previous field-trial. Above domestic hot water consumption values of 15 MJ day−1, the coefficient of determination (r2 value) was 0.98. The average error (difference between the average model predictions and the measured values) was 3.0% (in relative terms) while the root mean square error was 4.2%. The maximum error for a single point was 8.7% at a domestic hot water consumption of approximately 30.2 MJ day−1.