Type
Depending on the set of functions, boilers are divided into single-circuit and dual-circuit.
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Single-circuit boilers are equipped with one heat exchanger, in which the heat from fuel combustion is transferred to the heat medium of the heating system. The only function of such boilers is space heating. It is technically possible to use single-circuit boilers to provide hot water, but this requires an additional tank (the so-called indirect water heater).
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dual-circuit boilers, the primary heat exchanger is supplemented by a secondary one. Due to this, such a boiler, in addition to heating the room, also provides a hot water supply. In this case, both running water and water accumulated in a special tank(see Built-in water heater tank) can be used.
DHW circuit max. pressure
The maximum pressure in the hot water circuit (DHW) at which it can operate for a long time without failures and damage. See "Heating circuit maximum pressure".
DHW min. T
The minimum temperature of domestic hot water (DHW) supplied by a dual-circuit boiler. For comparison, we note that water begins to be perceived as warm, starting from 40 °C, and in centralized hot water supply systems, the temperature of hot water is usually about 60 °C (and should not exceed 75 °C). At the same time, in some boilers, the minimum heating temperature can be only 10 °C or even 5 °C. A similar mode of operation is used to protect pipes from freezing during the cold season: the circulation of water with a positive temperature prevents the formation of ice inside and damage to the circuits.
It is also worth keeping in mind that when heated to a given temperature, the temperature difference ("ΔT") may be different — depending on the initial temperature of the cold water. And the performance of the boiler in the DHW mode directly depends on ΔT; see below for performance details.
DHW max. T
The maximum temperature of domestic hot water supplied by a dual-circuit boiler. For comparison, we note that water begins to be perceived as warm, starting from 40 °C, and in centralized hot water supply systems, the temperature of hot water is usually about 60 °C (and should not exceed 75 °C). Accordingly, even in the most modest models, this figure is about 45 °C, in the vast majority of modern boilers, it is not lower than 50 °C, and in some models, it can even exceed 90 °C.
Also when heated to a given temperature, the temperature difference ("ΔT") may be different — depending on the initial temperature of the cold water. And the performance of the boiler in the DHW mode directly depends on ΔT; see below for performance details.
"Summer" mode
It is an operating mode designed for the warm season. In this mode, it works only to provide domestic hot water, and the heating is turned off. If the boiler is equipped with an outside temperature sensor, this sensor is also switched off in
summer mode so that the heating does not turn on at night when the outside temperature drops.
Mains water intake
The diameter of the pipe for connecting the pipe through which cold water is supplied to the boiler for heating and use in the hot water supply system.
Diameters are indicated in inches. It is allowed to connect a pipe of a different diameter through an adapter, but the best option is still a match in size. There are connection options
1/2",
3/4",
1" and
1 1/2".
DHW flow
The diameter of the pipe for connecting the pipe through which hot water leaves the boiler for the DHW system.
Diameters are indicated in inches. It is allowed to connect a pipe of a different diameter through an adapter, but the best option is still a match in size.
