Water heaters are an indispensable companion in daily life. In hot summer, nothing beats a refreshing shower after sweating. Even in cold winter when daily bathing may not be practical, people still take a shower every two to three days.
Nowadays, water heaters mainly fall into two categories. The first is the pre‑heating type. You need to turn on the water heater in advance to heat water before bathing. The storage‑type electric water heater belongs to this category. The second type delivers hot water quickly. It cannot produce hot water instantly upon startup; pre‑heating takes roughly 30 seconds to 5 minutes depending on seasons and product models. Gas water heaters and instant‑electric water heaters fall into this group, also known as constant‑temperature water heaters. Today we will talk about gas water heaters — one type of such constant‑temperature products — and figure out whether they can truly maintain constant water temperature.
First, let us learn about gas water heaters. They take gas as fuel. Through combustion‑based heating, heat is transferred to cold water flowing through the heat exchanger to produce hot water. To achieve constant‑temperature output, the outlet‑water temperature will remain nearly unchanged provided that the inflow rate, inlet‑water temperature and gas supply stay stable. Practical tests confirm this result.
In daily scenarios, opening other taps will change the water inflow. When other appliances are turned on, gas supply and gas pressure will also fluctuate. Both factors will affect outlet‑water temperature. Since human bodies are not highly sensitive to minor temperature deviations, gas water heaters are equipped with an automatic adjustment module. When gas pressure rises or drops, the module automatically narrows or widens the gas supply valve to stabilize gas output. Meanwhile, it adjusts gas supply volume according to the set water‑temperature value, realizing automatic regulation of water flow and gas volume.
Such modules are divided into water‑flow servo devices and automatic water‑volume adjustment devices. The water‑flow servo device supports a wider constant‑temperature range, while the automatic water‑volume adjustment device works within a narrower range. Even so, its coverage fully meets common hot‑water usage requirements (38 ℃‑47 ℃). Some users may wonder why the temperature range is relatively low. It is because gas‑water‑heater‑heated water is used directly for showering. By contrast, storage‑type electric water heaters require mixing hot water with cold water to get a comfortable bathing temperature. The two adopt different working principles.
Note that constant‑temperature performance does not hold under extreme conditions. For instance, in some regions of Northeast China where temperature drops to ‑40 ℃, non‑insulated outdoor‑mounted water heaters may fail to keep stable temperature; certain indoor units may face the same problem.
By now you may have gained a basic understanding. There is no “true or false” constant‑temperature gas water heater; products merely differ in their constant‑temperature working range. Hope the above content is helpful to you. If you have any questions, please click the customer‑service icon on the right side of the page.
