A heating boiler is a device based on a closed vessel in which the heat-carrying fluid is heated to a preset temperature. Serves to provide consumers with heat and (or) hot water.
There are two types of boilers:
Left - single-circuit gas boiler
On the right is a double-circuit gas boiler
Single-circuit boilers work either in the heating system or in the hot water supply system.
Double-circuit boilers - perform both functions at the same time.
When calculating the power of heating boilers, the following ratio is used: 1 kW of boiler power heats about 10 m2 of a well-insulated room (ceiling height up to 3m). For double-circuit boilers, consider the power reserve increased by 20-30%.
Boilers, depending on the type of fuel, are of various kinds:
Gas boilers are characterized by high efficiency of fuel combustion, controlled gas consumption, and automatic operation.
There are several conventional classifications of gas boilers:
By location:
By functionality:
By type of traction:
By type of ignition:
The subtype of gas boilers - condensing boilers. The name of this equipment is due to the ability to select from the combustion products "latent" heat obtained by condensation of the water vapor contained in them. This heat, usually leaving together with the flue gases, allows the boiler to reach an average conditional efficiency of 107-109% during the heating period.
Electric boilers require a large power (15-30 kW), respectively. To connect an electric boiler, a large cross-section cable is needed. They work silently, do not require a chimney, and are easy to operate.
However, they have several disadvantages: the high price for electrical energy and possible interruptions in its supply, which can be compensated for by installing additional electrical appliances (uninterruptible power supply system, generator).
The main element of electric boilers is heating elements (Tubular electric heater or heating element). The service life of the heating element directly depends on the chemical composition of the heat-carrying fluid, high salt content in the water can lead to accelerated corrosion of the metal of the heating element.
The principle of induction heating is based on the phenomenon of electromagnetic induction - the creation of an induced current by an alternating magnetic field. The induction heating installation has a design like a transformer, consisting of two circuits. The primary circuit is a magnetic system; the secondary circuit is a heat exchanger or fuel element (fuel element).
Under the influence of an alternating magnetic field created by a magnetic system, currents are induced in the heat exchanger's metal, causing it to heat up. The heat from the heated surfaces of the heat exchanger is transferred to the heated medium.
Induction boilers have a high cost due to the high-frequency converter and large dimensions and weight. But the absence of heating elements excludes the possibility of failure of the boiler itself, and the lack of detachable connections in the structure excludes the likelihood of a leak.
The process of heating the heat-carrying fluid in an electrode-type electric water heater occurs due to ohmic heating. This means that the process of heating the heat-carrying fluid goes directly, without an "intermediary" (for example, heating elements).
Electrode boilers are more compact than heating elements. An electric current in electrode boilers is passed directly through the heat-carrying fluid, which significantly increases the risk of electric shock. Due to the huge leakage currents, it is impossible to use a residual current device in conjunction with such a boiler.
The least efficient boilers are powered by firewood and coal. They are installed mainly in places where there are no gas networks. Large reserves of solid fuels are required.
There are several types of solid fuel boilers:
They work on wood, preferably as dry as possible, to ensure the minimum formation of soot and ash. Efficiency up to 85%.
They consist of two chambers: the first (upper) where firewood is laid, and the second (lower), where combustible gas from burning firewood accumulates in the upper chamber. This gas mixes with secondary air at the burner nozzle. In this case, not only firewood burns but also the gas emitted from them.
Powered by special fuel - pellets. Pellets are small dry granules made of wood.
The boiler can work without human intervention for up to several weeks, depending on the capacity of the hopper, from which the pellets are continuously supplied enter the boiler. At the same time, the pellet feed rate can be adjusted to add power to the boiler. The cost of pellets is much higher than ordinary firewood or coal, but the convenience of using boilers pays off the charges.
To compensate for the fact that solid fuel boilers cannot work for a long time in automatic mode, you can use heat accumulators involved in the heating system circuit.
A heat accumulator is an insulated tank, the dimensions of which depend on its capacity.
When the boiler is in operation, the water is heated to 80-95º С. And with the help of a circulation pump, the volume of heated water in the tank provides a constant heating mode for several days.
They run on diesel fuel. A burner plays the leading role in the operation of a liquid fuel boiler with a fan. It sprays fuel. In the combustion chamber, the fuel mixes with oxygen and ignites. From burning, the fuel mixture is heated by a heat exchanger with a heat-carrying fluid.
The operation requires the storage of significant fuel reserves and requires electrical energy to connect and power the fuel pump and automation systems.
The efficiency range for these boilers is 75-85%. Diesel boilers are available in the most autonomous configurations. Boiler automation and automatic fuel supply allow minimizing the presence of a person to service the boiler.
To install the boiler, a combustion room is required to hide the noisy operation of boilers of this type. In addition, the burning of diesel fuel is accompanied by oily odors.
It allows the use of different types of fuel for heating and hot water supply. Models of boilers with electromechanical control make it possible, if necessary, to transfer the boiler plant to the manual regulation mode without losing the functioning of the boiler plant.
There are several options for boiler combinations: