Describes WATSIM, a microprocessor-based WATer heating SIMulation code offering rapid, inexpensive analysis of potable water heating systems for both residential and commercial applications. It consists of two algorithms, one being a water heater tank model capable of simulating almost any water heating tank operating strategy and configuration, the other produces water draw-off profiles for use with the tank model. Gives some results of independent tests of the model. Claims it is the fastest practical program available for accurate equipment design and sizing purposes.

KEYWORDS: Calculating, domestic, hot water supply, algorithms.