HOTCALC Microcomputer software for analysis of commercial water heating system performance

The application, design, and sizing of commercial water heating systems has been hampered by the lack of an accessible tool for evaluating long-term performance and operating energy costs. This lack of resources has limited the application of high-efficiency alternative water heating systems such as heat pump water heaters, refrigeration heat reclaim units or desuperheaters, and waste heat recovery systems. The Electric PowerResearch Institute and the Empire State Electric Energy Research Corporation have developed the HOTCALC microcomputer software to fill that need. HOTCALC uses a three-node stratified tank model and hourly performance simulations for each month to provide performance estimates for five system types: electric storage water heaters, fuel?fired storage water heaters, heat pump water heaters, refrigeration heat reclaim, and waste heat recovery. A detailed recirculation loop model is included. HOTCALC is the first water heating analysis software that addresses the dynamic performance of heat pump water heaters and refrigeration heat reclaim systems, and the first to consider interactions between space cooling loads and heat pump water heater operation. Unlike other common models, it uses hourly inputs rather than longer-term average load and operations figures. Outputs include energy consumption, estimated demand, efficiency, and utility cost for all water heating system components. For heat pump water heaters, estimates of beneficial cooling output and value are provided. HOTCALC is designed for easy use and includes features for comparison of results from multiple runs, results and system design diagnostics, and a detailed context?sensitive help system with page references to ESEERCO's and EPRI's companion 310-page Commercial Water Heating Applications Handbook, EPRI TR-100212. HOTCALC provides reliable performance estimates and removes much of the uncertainty in system selection and design, thus facilitating the use of more efficient and effective commercial water heating systems. Reactions from users have been positive and comparisions to measured performance data have been very favorable.