A numerical model was developed for estimating the heat loss (or heat gain) from insulated or noninsulated hot water pipes. The model developed simulates the two-dimensional temperature distribution in the water, pipe walls, and any insulation as a function of time for steady flow or no flow (standby) conditions. The data obtained for field and laboratory experiments described in a companion paper are compared to the simulation results of the model. The model flow conditions can be specified over a relatively short time span so that almost any draw schedule can be modeled. With the ability to model a range of parameters, the resulting simulations can be used for comparative studies, such as establishing the heat loss differences between insulated and noninsulated piping and calculating the effect of various pipe diameters on the outlet water temperature. The model simulations are also compared to previous design guidelines, and suggestions are given for the use of design practices and the numerical model.

Units: Dual