A Simple Method to Continuous Measurement of Energy Consumption of Tank Less Gas Water Heaters for Commercial Buildings

Abstract

energy consumptions of hot water supply in restaurants or residential houses are large amount, guidelines for optimal design are not presented. measurements of energy consumption of tank less gas water heaters very difficult unless gas flow meters were installed. however a gas flow meters is hardly installed for individual heater. in this study, a simple method to estimate gas consumption of such appliances form temperature of exhaust gas and electric current was presented. experiments of japanese major hot water gas heaters were conducted change under conditions of various water flow rate at constant output temperature. the empirical equations, which related gas consumption to exhaust gas temperature and operative current, were obtained for each type of water heaters, each manufacturer and overall heaters. verification of the method was conducted at a commercial building. some thresholds to decide status of operation, such as anti-freeze operation, were set, and sufficient accuracy of around 10 % error was achieved.