Min. heat output
The minimum heat output at which the heating boiler can operate in constant mode. Operation at minimum power allows you to reduce the number of on-and-off cycles that adversely affect the durability of heating boilers.
Power supply
The type of electrical supply required for normal operation of the boiler. Power supply may be required not only for electric models but also for other types of boilers (see "Power supply") — in particular, for the operation of control automation. Connection options can be:
—
230 V. Work from a household system with a voltage of 230 V. At the same time, models with a power consumption of up to 3.5 kW can be connected to a standard outlet, but for high consumption devices, you need to connect directly to the distribution board. Many of the electric boilers with this connection also allow operation from 400 V (see below).
—
400 V. Operation from a three-phase system with a voltage of 400 V. This power supply is suitable for boilers with any power consumption. However, it is not as common as 230 V: in particular, it may be difficult to use it in a residential area. Therefore, this option is provided mainly in high-power devices for which a 230 V power supply is not suitable.
— Autonomous work. Work in completely autonomous mode, without an electricity connection. This format of operation is found in all boilers that do not use electrical heating (see "Energy source"), except for purely liquid fuel ones — in them, electricity is necessary for the operation of the fuel supply systems.
Rated current
The current consumed by the electric boiler (see "Power source") during normal operation.
This parameter directly depends on the power. It is required primarily for organizing the connection: wiring and automation must safely deal with the current consumed by the unit.
Coolant min. T
The minimum operating temperature of the heat medium in the boiler system when operating in heating mode.
Coolant max. T
The maximum operating temperature of the heat medium in the boiler system when operating in heating mode.
Heating circuit max. pressure
The maximum pressure in the heating circuit of the boiler, at which it remains operational, and there is no risk of physical damage to the structure. For a heating system, the maximum pressure is usually about 3 bar, and for a domestic hot water circuit up to 10 bar. When the maximum pressure is exceeded, a safety valve is activated, and part of the water is discharged from the system until a normal pressure level is reached.
Heated floor mode
The boiler has a special
mode for underfloor heating systems.
Underfloor heating differs from conventional heating systems primarily by a
lower coolant temperature — otherwise the floor could be too hot for comfortable use (plus, high temperatures are also undesirable for flooring and furniture installed on it). In addition, boilers with this function are distinguished by increased pump power. In order to ensure efficient circulation of the coolant through branched heating circuits that have rather high resistance.
Circulation pump
The presence in the boiler of
circulation pump.
Such a pump ensures the movement of the coolant along the heating circuit, due to which the heat is evenly and efficiently distributed over the radiators. Similar devices are also available as separate devices; however, buying a boiler with a circulation pump eliminates the need to purchase additional equipment and simplifies the heating system. The disadvantages of such models include the complex design: if a separate pump fails, it is enough to replace only it, and the module built into the boiler may require complex and expensive repairs, and the heating system becomes unavailable.
Also note that it is theoretically possible to build a heating system without a pump, based on natural circulation; however, such systems have several disadvantages, so it is still preferable to use forced circulation.
Control bus
The control bus with which the boiler is compatible.
The control bus is a communication channel through which control and controlled devices can exchange data. Support for such a channel greatly simplifies the connection of thermostats and other control automation. It is enough that such devices are compatible with the same bus as the boiler. In addition, many types of tyres allow you to create very extensive monitoring and control systems and easily integrate various devices into them, including heating boilers.
In modern heating technology, the most popular tyres are
OpenTherm,
eBus,
Bus BridgeNet and
EMS. Here are their key features:
— OpenTherm. A fairly simple standard with modest functionality: it allows only a direct connection between the control and the controlled device and is not designed to create extensive systems. On the other hand, this bus has quite advanced capabilities for controlling heaters: in particular, it allows you to control the temperature not just by turning the boiler on/off, but by changing the power of the gas burner. This mode of operation contributes to saving fuel/energy, as well as reduces wear and increases the life of the heater; and in many cases, a system of two devices (boiler and thermostat) is quite enough for effective heating control. At the same time, the OpenThe
...rm standard is simple and inexpensive to implement, which makes it extremely popular in modern boilers. For several reasons, it is mainly used in gas models.
— eBUS. A control bus that has some pretty impressive features. Allows you to combine up to 25 control and 228 controlled devices in one system, with a data transmission distance between individual components up to 1 km. At the same time, eBUS is an open standard, its implementation (at least within the framework of the main functions) is freely available to everyone. And although nowadays eBUS support can be found mainly in Protherm and Vaillant equipment. However, in boilers, this is the second most popular type of control bus, after OpenTherm. It is mainly due to slightly higher cost, while advanced eBUS capabilities are not needed as often.
— Bus BridgeNet. Hotpoint-Ariston proprietary development, used exclusively in boilers of this brand. One of the advantages is a high degree of automation: the user only needs to set the temperature parameters (and for different zones, you can choose custom
options) and, if desired, a weekly programme, the rest of the necessary calculations and adjustments will be carried out by the system. However, such features are available only in special control devices such as temperature controllers; in boilers, Bus BridgeNet support usually means only compatibility with such automation.
— EMS. A control bus used primarily in Bosch and Buderus equipment. In general, it is characterized by wide functionality, a high degree of automation and the ability to create extensive control systems. However, note that nowadays you can find both the original EMS and the modified EMS Plus, and these standards are not initially compatible with each other (although support for both of them may well be provided in some devices). So the specific version of the EMS bus should be specified separately. We note that in Bosch devices there is mainly an original version, and in Buderus devices — EMS Plus (although exceptions are possible there and there).
