Analysis Of The Impact Of The Domestic Hot Water Piping Heat Loss On The System And Economic Efficiency

The consumption of hot sanitary water is an important part of building’s energy consumption. With the improvement of our living standards and life quality, consumption of building hot water is rising up firmly.Both the relevant standards and the researchers did not concern about the piping heat loss impact on system efficiency and economy of domestic hot water system. This paper have investigated hot water consumption and pipe status in 256 urban buildings of Hunan Province, and then analyzed the influencing factors of heat loss of hot water pipe and its impact on the energy efficiency. For the typical water supply mode in a family of three, this article compares gas, electric and solar hot water systems under the current energy price system under the effect of piping heat loss. The main research contents and conclusion are as follows:1. This thesis did a building energy consumption survey in 256 urban residents in 4 cities of Hunan Province. And it shows that about 99% of the families use hot water system when bathing, and home solar, electric and gas hot water systems are the most common households. Through the actual measurement we know that the average flow rate and time are 6.633 L / min and 11.24 min each time bathing. The average length of hot water pipes is 6.69 m. The average length of outdoor pipes is 8.3m for families who have solar water heating systems.2. The current standards of water heater efficiency evaluation are for the water heater itself, and it ignored the impact of piping heat loss on system efficiency. Analyzing the factors affecting the heat loss of domestic hot water pipes bases on the survey data and typical operating conditions, and it needs to do research on how the heat loss of house pipes affects the efficiency of domestic hot water system. The factors affecting the heat loss of domestic pipes are mainly climatic conditions, category of pipes, length of pipes, the way of installation, and the hot water temperature in the outlet.3. Basing on the meteorological data in typical meteorological year of Changsha, and makes a comparison of heat loss economic impact among home gas, electricity and solar hot water systems in the energy price system. The overall energy price of gas hot water systems is 0.289 yuan / kwh, and electric hot water system 0.568 yuan / kwh. Energy prices of three commonly used solar hot water system installed in floors from one to five are between 0.225- 0.251 yuan / kwh. If only consider system comprehensive energy prices(M) and efficiency coefficient(CTP), the solar water heating system is better than the gas one considering the economy, more obvious superiority compared with the electric hot water system. Based on economic considerations, it is recommended that if users live under floor 5 in Hunan province, they should choose a solar hot water system.