It’s hard to feel the pain of winter living in Guangdong. Even in November, the temperature in the daytime is still above 25 ℃, and you can even sweat when you go out to eat at noon. However, for most parts of the country, especially the Yangtze River, winter is often a torment. When I used to live in my hometown, the last thing I wanted to do in winter was to take a bath. I had to take off my thick clothes every time. Then I shivered in the bathroom, waiting for the water heater to heat for dozens of seconds, which may be one of the longest times in my life. In recent years, the need for hot water in winter has become a pain point for more and more users. Therefore, a product called zero cold water heater has been paid more and more attention. What is it? Is it worth buying? Let’s talk about this topic today. < p > < p > as the name implies, zero cold water heater can achieve the effect of “zero cold water”. In theory, when you turn on the tap at any time, all the hot water comes out. Of course, this is only theoretical. In fact, all zero cold water heaters still have a certain waiting time, which is generally about 5 seconds, which is much faster than tens of seconds or even one minute of non-zero cold water heaters. < / P > < p > don’t underestimate the improvement of these tens of seconds. In winter, the user experience can be changed qualitatively. You can make up for the difference between getting up in the middle of the night, going to the toilet and turning on the tap to get in touch with hot water and cold water. One can make you warm and comfortable, and the other can make you sleepless. How does it work? In fact, the principle is not complicated. It mainly has two more parts than the ordinary water heater, one is the return valve or return pipe, and the other is the circulating water pump. < / P > < p > the function of the return valve (called one-way valve in the figure) is to connect the cold water pipeline and hot water pipeline of the house to form a closed loop. The return pipe connects the farthest end of the hot water pipe to the water inlet of the water heater to form a closed loop. The cold water and hot water pipes of the house are still independent and disconnected. The principle is not the same, but the effect is consistent. The function of the water pump is to make the water circulating again. < / P > < p > we don’t need to study how the pipes are connected. As long as we know that the principle of zero cold water heater is to pump the cold water in the pipe into the water heater for heating, and then send it back to the pipe. In this way, you can turn on the tap and it will be hot water, and there is almost no need to wait. Moreover, the zero cooling water heater can automatically detect the temperature of water in the pipeline. If it turns cold, it will start circulating heating again to keep the water in the pipeline hot. However, the zero cold water heater can not achieve zero cold water completely, mainly because it can only heat the cold water in the circulating pipeline. For example, the water in the shower head and faucet does not belong to the closed-loop pipeline, so it cannot be pumped into the water heater for heating. When opening the faucet, it must wait for the cold water in the shower head to flow out, which generally takes several seconds. < / P > < p > the structure of the zero cooling water heater is not different from that of the ordinary gas water heater, and the installation method is the same. The only difference is that the zero cold water heater needs a return pipe or a return valve. < / P > < p > the return pipe needs to be embedded into the wall when decorating the house. If it is not done during the decoration, it can be replaced by the return water valve. The principle is a little different, but the effect is the same. The installation position of the return valve must be at the farthest end of the house water, which is generally the farthest water point from the water heater, so as to achieve the effect of whole house circulation. < / P > < p > one is that there are two water inlet pipes in the family. Although most new houses are one water inlet pipe, a small number of developers, some old houses and some unreliable decoration companies may use two water inlet pipes. Generally, there is a kitchen and a toilet. It’s easy to distinguish. You just need to close one inlet valve in turn to see if there is cold water in the other place. It is stated that zero cold water can not be installed, and there is no instruction to install it. < / P > < p > the other is that there are water purifiers and other water equipment that are afraid of high temperature, and there is no embedded return pipe. The one-way valve mentioned above can achieve the same effect as the return pipe, but the circulation path is different. The installation of one-way valve means that the cold water pipeline in the home will be connected with the hot water pipeline, so that all water terminals will inhale hot water, and the filter element of the water purifier can not withstand the temperature above 40 ℃ High temperature, so the forced use of zero cold water will damage the water purifier. < / P > < p > when there is a return pipe, the circulation route of the water heater is only on the hot water pipeline, which will not interfere with the cold water pipeline, so this structure does not need to worry about the use of water purifier and other equipment. < / P > < p > the value of zero cold water heater is not worth buying. It is mainly judged from the cost and effect of use. First of all, in terms of price, most zero cold water heaters are more expensive than ordinary water heaters, but at present, 2000 yuan can also buy many products, and the trend in the future is definitely getting cheaper and cheaper, so the price is not a problem. < p > < p > relatively speaking, consumers are more concerned about the cost of daily use. After all, the zero cold water heater often heats the water in the pipe, and people will think that the gas consumption and power consumption will be higher than the ordinary water heater. According to the actual measurement, the maximum power of the gas water heater is only about 20 watts, and the electricity charge is almost negligible. The gas consumption has not increased too much. The zero cooling water heater generally supports opening in different periods. It can automatically turn off the zero cooling water function when not at home in the daytime, and turn on the zero cooling water before going off duty at night. < p > < p > in general, the zero cooling water heater is worth buying, and it will be popularized gradually in the future. However, there are more or less small defects in the current products, such as easy to start by mistake, resulting in additional gas consumption. Compared with the ordinary water heater, there are more circulating pumps, higher ignition frequency, life and failure rate need to be verified. Moreover, if the return pipe is not embedded in the decoration, but replaced by the return valve, the pipeline of the cold water pipeline and water purifier may be affected. < / P > < p > finally, if you want to enjoy the zero cold water effect, but you don’t want to replace the original water heater, there is an alternative solution: add a “small kitchen treasure” under the faucet, which can be regarded as an instant electric water heater, filling the blank period of waiting for the remote water heater to heat up. The price is generally several hundred yuan, which is more convenient and economical. Spontaneous combustion at a Guangzhou Motor vehicle intersection and other traffic lights in Shenzhen