Heating time
Time to heat the storage tank (see "Type"), filled with cold water, to operating temperature.
It is worth remembering that this characteristic is not 100% accurate. Manufacturers usually indicate the heating time for certain conditions: a filled tank, maximum heating intensity, and temperature rise (∆T) by a certain number of degrees. In practice, the heating time may differ, both one way and the other. For example, if the heating time for the device is 20 minutes at ∆T = 50 °C, then when the water is heated from 15 °C to 60 °C, the time will be shorter (∆T = 45 °C). Nevertheless, this indicator allows us to evaluate the overall flow rate of the boiler, and with equal ∆T and volumes, different models can be compared in terms of heating time.
Heating elements
The number of heating elements provided in the design of the water heater. In this case, it is the total number of elements that are taken into account, regardless of whether they belong to the same type or different ones: for example, 2 heat exchangers and 1 heating element are considered as 3 elements.
All gas models (see "Energy source") have only one heating element — this is quite enough for efficient operation. In
combined devices (see ibid.), on the contrary, there are several heating elements by definition (at least two — a heat exchanger and an electric one). In electric and indirect water heaters, the options may be different.
The meaning of several heaters of the same type is primarily to increase the heating efficiency. For example, in an instant (see "Type") electrical water heater, in this way, it is possible to increase the working length — the distance that water passes inside the device from inlet to outlet; by increasing the working length, the water is heated longer. In storage electric models, several heaters provide more uniform heating of the water, and in indirect ones, they allow more heat to be taken away. In addition, in indirect devices, heat exchangers can differ in the source of heating: for example, one can work from a heating boiler, the second from a solar collector.
Also, note that duplication of heating elements can also be used as protection against failures: if one of them
...fails, the heating efficiency decreases, but the device remains operational. However, this possibility is not available in all models with several heaters, its presence should be clarified separately.Functions
Among the functions of the water heater there are
thermostat,
water flow regulator,
Smart (auto mode),
programmer,
display and
control via the Internet. More about each of them
— Thermostat. A device that allows you to control the temperature of the water at the outlet of the heater. In storage models (see "Type"), the thermostat sets the maximum temperature for heating water in the tank; in instant devices, this function is carried out by changing the intensity of heating.
— Automatic water flow regulator. It is used in instant water heaters. Since the water in such devices heats up in the process of its movement through the heater, the higher the speed of water movement (the greater the pressure), the lower the heating temperature, and if the pressure is too high, the power of the device may simply not be enough for effective heating. The use of an automatic water flow regulator avoids this — this system regulates the speed of water movement through the heater, limiting it if necessary.
— Smart (auto mode). A special “smart” mode in which the boiler is controlled (primarily the intensity of heating) automatically. Specific features of this mode may vary depending on the model. However, the following format of operation is most common: during
...the first week of use, the device remembers at what time of the day the hot water was used, and then the heater’s operating mode adjusts to this data. Thus, the water heater provides the user with hot water at the right time and, at the same time, does not waste energy on heating during hours when heating is not needed.
— Programmer. The presence of a programmable thermostat — a device that allows not only to maintain the temperature but also to programme the operation of the device for a certain period. The simplest programmers work like a timer, turning on at the right time (vacation or holiday mode, when the device is not active for several days, and when the family returns to the house, it will turn on and heat the water). More advanced ones allow you to set the mode of operation for individual days. Either way, this feature provides added convenience and eliminates the need to constantly adjust the operation of the device manually. On the other hand, the presence of a programmer affects the cost.
— Display. Usually, a simple LCD screen with a few characters is used as a display. However, even such equipment significantly increases the convenience and information content of management. Various service data can be shown on the display — from the temperature of the water in the tank to messages about malfunctions and failures. This feature slightly increases the cost of the device, but compared to the total cost of the heater, this moment is usually insignificant.
— Control via the Internet. The specific nuances of such control may vary: for example, some models use a special application installed on a smartphone or tablet, while others can work through a regular browser from any computer. However, this function allows you to control the heater from almost anywhere in the world — provided that there is access to the Internet. In addition, with this control, the user can also monitor the status of the device and receive various notifications (on and off, about the temperature of the water in the tank, about various problems, etc.).Controls layout
Location of heater controls. It is worth choosing by this parameter, taking into account where it is planned to install the device and from which side access to it will be most convenient. For example, when installed in cramped conditions, the water heater can only be opened from the side or the bottom; for such cases, it is worth looking for a model with the appropriate location of the controls.
Tank manufacturer's warranty
The warranty period declared by the manufacturer for the storage water heater tank (see “Type”).
This parameter is important for the reasons of maintenance terms. The tank is the most complex element: other parts of the water heater are relatively easy to repair and change, and if there is a problem with the tank, it is often easier to replace the entire boiler. In the most advanced models, the warranty on the tank can be 10 years or more.
