What needs to be done so that hot water flows immediately after opening the tap?
Depending on the method of heating water hot water supply systems (DHW) for private country house subdivided into:
As instantaneous water heater can be used:
Flow water heater starts to heat the water at the moment the water is being parsed when the hot water faucet is opened.
All the energy spent on heating is transferred from the heater to the water almost instantly, for a very short time of movement of water through the heater. In order to obtain water of the required temperature in a short period of time, the design of an instantaneous water heater provides for limiting the flow rate of water. The water temperature at the outlet of the instantaneous heater is very dependent on the water flow — the amount of hot water flowing from the faucet.
For a normal supply of hot water to only one horn in the shower, the capacity of the instantaneous water heater must be at least 10 kW. You can fill the bathroom in a reasonable time from a heater with a capacity of more than 18 kW. And if, when filling the bath or operating the shower, you also open the hot water tap in the kitchen, then for comfortable use of hot water, you will need an instantaneous heater power of at least 28 kW.
For heating an economy class house, a boiler of lower power is usually sufficient. So, the power of the double-circuit boiler is chosen based on hot water demand.
The DHW scheme with an instantaneous water heater cannot provide comfortable and economical use of hot water in the house for the following reasons:
The temperature and pressure of water in the pipes are very dependent on the amount of water flow. For this reason when another tap is opened, the water temperature and pressure in the DHW system change very much. It is not very comfortable to use water even in two places at the same time.
Ultimately, the use of an instantaneous water heater in the DHW system leads to an unreasonable increase in water consumption and volume of sewage, to an increase in energy consumption for heating, as well as to insufficiently comfortable use of hot water in the house.
A DHW system with an instantaneous water heater is used, despite its shortcomings, due to relatively low cost and small size of equipment.
The system works better if install a separate individual instantaneous water heater near each point of water analysis.
In this case, it is convenient to install electric flow heaters. However, such heaters during the analysis of water at the same time in several places can consume significant power from the mains (up to 20 - 30 kW). Usually, the power grid of a private house is not designed for this, and the cost of electricity is high.
The main parameter for choosing an instantaneous water heater is the amount of water flow that it can heat.
For example.
Three points of analysis are connected to one instantaneous water heater - a sink in the kitchen, a washbasin and a bath (shower). To fill only the bath, you must select a heater that is capable of delivering at least 9 l/min. water with a temperature of 55 about C. Such a water heater will also provide the use of hot water simultaneously from two taps - in the sink and washbasin.
Using hot water at the same time in the shower and washbasin will be comfortable if the heater performance is already at least 9 l/min+4,2 l/min=13,2 l/min
Manufacturers in technical specifications usually indicate maximum performance instantaneous water heater, based on water heating for a certain temperature difference, dT, e.g. 25 about C, 35 about C or 45 about C. This means that if the temperature of the water in the water supply is +10 about C, then at maximum performance, water with a temperature of +35 about C, 45 about C or +55 about C.
Be careful. Some sellers in advertising indicate the maximum performance of the device, but "forget" to write for what temperature difference it is determined. You can buy a geyser with a capacity of 10 l/min., but it turns out that at this flow rate it will only heat the water by 25 about C., i.e. up to 35 about C. Using hot water with such a column may not be very comfortable.
Suitable for our example geyser or double-circuit boiler with a maximum capacity of at least 13.2 l/min at d T=45 about C. The power of the gas apparatus with these hot water parameters will be about 32 kW.
When choosing an instantaneous water heater, pay attention to one more parameter - minimum performance, consumption l/min at which the heating is turned on.
If the water flow in the pipe is less than the value specified in the technical characteristics of the device, the water heater will not turn on. For this reason, often use more water than is necessary. Try to choose a device with the lowest possible minimum performance, for example, no more than 1.1 l/min.
Electric instantaneous water heaters intended for domestic use have a maximum heater power of about 5.5 - 6.5 kW. At maximum performance 3.1 - 3.7 l/min heat water by d T=25 about C. One such water heater is installed to service one water point - a shower, a washbasin or a sink.
A storage water heater (boiler) is a heat-insulated metal tank of a rather large volume.
In the lower part of the water heater tank, two heaters are most often built in at once - an electric heating element and a tubular heat exchanger connected to a heating boiler (). The water in the tank is heated most of the time by the boiler.
The electric heater is switched on as needed, during the shutdown of the boiler. Such a boiler is often called indirect heating boiler.
Hot water in an indirect heating boiler is consumed from the top of the tank. In its place, cold water from the water supply immediately enters the lower part of the tank, is heated by a heat exchanger and rises.
In the countries of the European Union DHW systems in new houses, it is mandatory to equip with a solar heater - a collector. To connect the solar collector another heat exchanger is installed in the lower part of the indirect heating boiler.
AT recent times the hot water system with a layered heating boiler is gaining popularity, the water in which is heated by an instantaneous water heater. In such a boiler there is no heat exchanger, which reduces its cost.
Hot water is drawn from the top of the tank. In its place, cold water from the water supply immediately flows into the lower part of the tank. The pump pumps water from the tank through the flow heater, and is supplied immediately to upper part tank. Thereby, hot water at the consumer appears very quickly- no need to wait until almost the entire volume of water warms up, as happens in an indirect heating boiler.
Rapid heating of the top layer of water, allows you to install a smaller boiler in the house, as well as reduce the power of the instantaneous heater, without sacrificing comfort.
The Galmet SG (S) Fusion 100 L layered heating boiler is connected to the DHW circuit of a double-circuit boiler or to a geyser. The boiler has a built-in three-speed circulation pump. Boiler height 90 cm, diameter 60 cm. Manufacturers produce double-circuit boilers with a built-in or remote layered heating boiler. As a result,the cost and dimensions of the equipment of the DHW system are somewhat less,than with an indirect heating boiler.
The water in the boiler is heated in advance, whether it is spent or not. The supply of hot water in the tank allows you to use hot water in the house for several hours.
Due to this, the water in the tank can be heated for quite a long time, gradually accumulating thermal energy in hot water. Hence another name for the boiler - accumulative water heater.
Long duration of water heating allows use a heater of relatively low power.
Storage boilers, in which water is heated by a gas burner, are less popular in systems DHW private Houses. The device in the house of heating and hot water systems with two gas appliances - a gas boiler and a gas boiler, turns out to be much more expensive.
Accumulative gas water heater - boiler It can be beneficial to install gas boilers in apartments with central heating or in private houses with solid fuel boiler heating and water heating in the DHW system with liquefied gas.
Gas water heaters, as well as boilers, are produced with open cam combustion and with closed, with forced removal flue gases and with natural draft in the chimney.
On sale there are storage gas boilers that does not require connection to the chimney. (Household gas stoves they also work without a chimney.) The power of gas burners of such devices is small.
Gas boilers up to 100 liters are designed for wall mounting. Large volume water heaters are installed on the floor.
Used in water heaters different ways ignition gas- with an on-duty wick, battery-powered electronic or hydrodynamic ignition.
In devices with standby wick a small flame burns constantly, which is first ignited by hand. Some amount of gas burns uselessly in this torch.
Electronic ignition Runs on mains power or batteries.
Hydrodynamic ignition It is started from the rotation of the impeller, which is driven by the flow of water when the tap is opened.
The larger the volume of the storage water heater, the higher the comfort of using hot water in the house. But on the other hand, the larger the boiler, the more expensive it is, the higher the cost of its repair and Maintenance the more space it takes up.
The size of the boiler is chosen based on the following considerations.
Increased comfort will be provided by a boiler, the volume of which is selected at the rate of 30 - 60 liters per user of water.
A high level of comfort will be provided by a water heater with a volume of 60-100 liters per person living in the house.
To fill the bath, you need to use almost all the water from a boiler with a volume of 80 - 100 liters.
When choosing a boiler, it is necessary to pay attention to the power of the heating element that is installed in it. For example, to heat 100 liters of water to a temperature of 55 about C in 15 minutes, a heater (heat exchanger for the boiler, built-in gas burner or heating element) with a capacity of about 20 kW.
Under real operating conditions, the temperature of the water in the boiler is equal to the temperature of the water in the water supply only when the heating is turned on for the first time. In the future, in the boiler there is almost always water already heated to a certain temperature. To heat water to the required temperature in a reasonable time, use heating devices less power.
But still, it is better to check how long it will take to heat the water in the boiler. This can be done using the formula:
t = m cw (t2 – t1)/Q, wherein:
t– water heating time, seconds ( with);
m- the mass of water in the boiler, kg (the mass of water in kilograms is equal to the volume of the boiler in liters);
cw- specific heat capacity of water, equal to 4.2 kJ/(kg K);
t2- the temperature to which the water must be heated;
t1– initial water temperature in the boiler;
Q– boiler power, kW.
Example:
Water heating time by a boiler with a capacity of 15 kW in a 200-liter boiler from a temperature of 10 °C(we assume that the water entering the boiler has this temperature) up to 50 °C will be:
200 x 4.2 x (50 - 10)/15 = 2240 with, that is, about 37 min.
The use of a storage water heater in the DHW system allows you to organize the recirculation of hot water in pipelines. All hot water taps are connected to a ring pipeline through which hot water is constantly circulating.
The length of the pipe section from each point of hot water consumption to the ring pipeline should not exceed 2 meters.
Hot recirculation circulation pump DHW water has a small size and low power Recirculation of water in the DHW system is provided by a circulation pump. The power of the pump is small, a few tens of watts.
DHW pumps, unlike heating pumps, must have a maximum operating pressure at least 10 bar. Heating pumps are often designed for a maximum pressure of no more than 6 bar. Another difference is that the DHW pump must have a hygiene certificate that allows it to be used in drinking water systems.
Water in DHW systems is constantly updated and the oxygen content in it remains high enough. Corrosive activity of hot water is high. In addition, hot water must comply with sanitary requirements for drinking water. Therefore, for the manufacture of DHW pumps, corrosion-resistant non-ferrous metals or stainless steel are used. For these reasons, DHW circulation pumps are noticeably more expensive than those for heating systems.
In some designs of DHW pipelines, it is possible to create a natural recirculation of water, without a pump.
As a result of the circulation of water in the DHW system hot water is supplied to the points of selection constantly.
In a DHW system with a storage heater and water recirculation, the water supply mode is more stable:
The recirculation circuit allows not only to increase the comfort of water supply at remote points of the house, but also gives the ability to connect circuits to it warm floors in separate rooms. For example, in the bathroom, a water-heated floor will be comfortable all year round.
A DHW system with water recirculation constantly consumes energy for the operation of the circulation pump, as well as to compensate for heat losses in the boiler itself and in pipes with circulating water. To reduce energy consumption, it is recommended to install a circulation pump with a built-in programmable timer that turns off water circulation during hours when it is not needed. The boiler and hot water pipes are insulated.
As you know, a double-circuit gas boiler can provide a house with hot water and be a source of heat in the heating system. Preparation of hot water is carried out in the flow heat exchanger of the boiler. Read about the general disadvantages of a DHW system with a flow heater at the beginning of this article. But gas appliances there is another problem with a flow heater - this is the difficulty of choosing the maximum power of a double-circuit boiler or a hot water geyser.
Most often it turns out that required power boiler for hot water, much more power needed to heat all rooms in the house.
As mentioned in the article above, in order to obtain hot water of the required temperature and its maximum consumption, double-circuit gas boilers and hot water geysers have a large enough maximum power, about 24 kW . or more. Boilers and columns are equipped with automation, which can reduce their power to a minimum, equal to approximately 30% of the maximum, by modulating the burner flame. The minimum power of a double-circuit gas boiler or column is usually about 8 kW. or more. This is the minimum power of the boiler, both in DHW and heating mode.
Gas burner of a double-circuit boiler or column due to design features cannot work stably with power less than the minimum (less than 8 kW.). At the same time, to work with the heating system of a private house or autonomous heating apartments, the boiler in heating mode should very often give out a power of less than 8 kW.
For example, power 8 kW. enough to provide heat to the premises of a house or apartment with an area of 80 - 110 m 2, and in the coldest five days of the heating season. During warmer periods, the performance of the boiler should be significantly less.
Due to the fact that the boiler cannot work with a power below the minimum, there are problems with the adaptation (coordination) of the double-circuit boiler and the heating system.
In small facilities with low heat consumption for heating, the boiler produces more heat than the heating system can take. As a result of inconsistency between the parameters of the boiler and the system, the double-circuit boiler starts to operate in a pulsed mode, "clock"- as people say.
Work in the "clocking" mode significantly reduces the service life of boiler parts, significantly reduces efficiency.
heating diagram tap water double-circuit gas boiler or water heater, depending on the temperature ( T about C) and consumption ( Q l/min) hot water. The thick line shows the borders of the Working area. Gray zone, pos.1 - clock zone boiler or column (switching between ON/OFF). For normal water heating by a boiler or column, on the diagram, the point of intersection of the temperature and hot water flow lines (working point) must always be inside working area, the boundaries of which are shown in the diagram with a thick line. If the hot water consumption mode is selected so that the operating point will be in the gray zone, pos. 1 on the diagram, then the boiler, the column will clock. In this zone, with a small flow of water, the power of the boiler, column turns out to be excessive, the boiler, the column turns off from overheating, and then turns on again. From the tap comes either hot or cold water.
Double-circuit gas boilers, when operating at maximum power, have an efficiency of more than 93%, and less than 80% when operating at minimum power. Imagine how the efficiency will decrease even more if such a boiler has to operate in a pulsed mode, with constant re-ignition of the gas burner.
Please note that a double-circuit boiler operates at minimum power most of the time during the year. At least 1/4 of the consumed gas will literally fly uselessly into the pipe. Add to this the cost of replacing prematurely worn parts of the boiler. This will be a retribution for installing cheap equipment for heating and hot water in the house.
If the power of a double-circuit gas boiler is more than 20 kW., selected based on the heating of the maximum required hot water flow, then the boiler cannot provide economical and comfortable work in mode low power heating and when heating water with a small flow rate. The same can be said about the operation of the hot water column.
Most often, in the house there is no need to prepare large streams of hot water. For many people, it is much more important to provide comfortable and economical use of hot water at a low consumption.
For such economical hosts, many manufacturers produce double-circuit gas boilers and columns with a maximum power of about 12 kW. and the minimum is less than 4 kW. Such boilers, columns will provide more economical and comfortable heating and use of hot water in an amount sufficient for taking a shower or washing dishes.
Before buying a double-circuit boiler or column, the owners need to decide which mode of hot water consumption is more profitable and comfortable - with a large flow of water or with a small one. Based on this decision, choose the power of the boiler or column. If you want both, then you will have to choose a hot water system with a boiler.
For lovers of the shower, for preparing hot water and heating houses and apartments with a heated area of up to 140 m 2, with one bathroom capacity 12 kW. They are best suited to the needs of heating and hot water systems of small private houses and apartments.
For those who like to take a bath, as well as for houses and apartments large sizes, with an area of more than 140 m 2, I strongly advise you to use a single-circuit boiler.
Many manufacturers heating equipment they produce special kits, a boiler plus a built-in or remote boiler, just for such cases. Such a set of equipment will cost more, but will provide an increased service life of the equipment, gas savings and more comfortable use of hot water.
AT Western Europe and in the world, various ways to save energy during the operation of a private house are popular.
Hot water from the house after use flows into the sewer and carries away with it a significant part of the thermal energy that was spent on its heating.
Scheme for the recovery of thermal energy from sewage effluents to the DHW system To reduce energy losses in the house, a heat recovery (return) scheme is used from sewer drains to the hot water supply system of a private house.
Cold water passes through a heat exchanger before entering the DHW boiler. Effluent from sanitary appliances is sent to the heat exchanger.
In the heat exchanger, two streams, cold water from the mains and hot water from the drains, meet but do not mix. Part of the heat from hot water is transferred to cold water. Preheated water enters the DHW boiler.
In the diagram shown in the figure, only those sanitary appliances that work with a hot water flow are directed to the heat exchanger. It is advantageous to use such a recovery scheme for any method of water heating - both with a boiler and with a flow heater.
To recover heat from plumbing drains that first accumulate hot water and then drain it into the sewer (bath, pool, washing and dishwasher), apply more complex scheme with water circulation between the boiler and the heat exchanger while these devices are emptying.
For houses and apartments with permanent residence highly recommend to use DHW system with a stratified heating boiler and a double-circuit boiler, or with an indirect heating boiler and single boiler. The volume of the boiler is not less than 100 liters. The system will provide good comfort of using hot water, economical consumption of gas and water, as well as a smaller amount of wastewater to the sewer. The only disadvantage of such a system is that high price equipment.
With a limited construction budget in small country country houses for seasonal residence you can install a DHW system with a flow heater.
It is advisable to use a hot water supply scheme with a flow heater in houses with a kitchen and one bathroom, where the heating source and hot water taps are located compactly, at a short distance from each other. It is recommended to connect no more than three water taps to one instantaneous water heater.
The cost of such a system is relatively low. and the shortcomings of operation in this case are less pronounced. A double-circuit gas boiler or gas water heater takes up little space. Almost all the necessary equipment is mounted in the body of the device. For installation of a boiler with a capacity of up to 30 kW or geyser does not require a separate room.
For the preparation of hot water and heating houses and apartments with a heated area up to 140 m 2, with one shower in the bathroom, I recommend installing double-circuit gas boilers with a maximum capacity 12 kW.
In a hot water system with a geyser or a double-circuit boiler the stability of the water supply mode will increase significantly if the scheme install a buffer tank between the heater and the water taps- a conventional storage electric water heater. It is especially recommended to install such a buffer storage electric water heater near disassembly points remote from the gas appliance.
Read more: In a buffer tank scheme, hot water from a geyser or a double-circuit boiler first enters the tank of an electric boiler - water heater. Thus, the tank always contains a supply of hot water. The electric heater in the tank only compensates for heat loss and maintains required temperature hot water during the period when there is no water analysis. An electric water heater with a tank of small capacity is enough - even 30 liters, and using hot water will become much more comfortable.
Domestic hot water system with instantaneous water heater and built into the boiler or a remote boiler of layered heating will be somewhat more expensive. But here it will not be necessary to spend expensive electricity to maintain the temperature of the water, and the comfort of using water will be the same as with an indirect heating boiler.
In houses with an extensive DHW networkimplement a scheme with a storage water heater (boiler) and water recirculation. Only such a scheme will provide the necessary comfort and economical operation of the DHW system. True, the initial costs for its creation are the largest.
It is recommended to buy boilers that are sold complete with a boiler. In this case, the parameters of the boiler and boiler are already correctly selected by the manufacturer, and most of additional equipment built into the boiler body.
If the heating in the house is carried out by a solid fuel boiler, then it is advantageous to install, to which and connect the DHW system with water circulation.
Otherwise, for heating water in the house, attached to a solid fuel boilerindirect heating boiler, additionally equipped with an electric heater.
It is advantageous to use an electric hot water boiler in a house with a solid fuel boiler Often, only electricity is used to heat water in a house with a solid fuel boiler. For hot water in the house, near the points of water analysis, a storage electric boiler is installed - a water heater. The hot water circulation system is not made in this embodiment. Near remote points of water analysis, it is more profitable to install your own storage heater. In this case, electricity for heating water is spent more economically.
When water is heated above 54 about C hardness salts are released from the water. To reduce scale formation If possible, heat the water to a temperature lower than indicated.
Instantaneous water heaters are especially sensitive to scale formation. If the water is hard, contains more than 140 mg CaCO 3 in 1 liter, then the use of instantaneous water heaters for heating water, including those with stratified heating boilers, is not recommended. Even small deposits of scale clog the channels in the instantaneous heater, which leads to a cessation of the flow of water through it.
It is recommended to supply water to the instantaneous water heater through an anti-scale filter, which reduces water hardness. The filter has a replaceable cartridge that will have to be changed regularly.
For heating hard water, it is better to choose a DHW storage system with an indirect heating boiler. Salt deposits on the heating element of the boiler do not interfere with the flow of water, but only reduce the performance of the boiler. The boiler is easier to clean from scale.
It should be remembered that prolonged heating of water to a temperature of less than 60 ° C can lead to the appearance of Legionella bacteria harmful to human health in a storage tank (boiler) with hot water. Recommended periodically perform thermal disinfection of the DHW system, raising the temperature of the water to 70 ° C for some time.
Hot water in an apartment or house has always been an integral part of comfort, without which a modern person cannot imagine his life. It is not uncommon for hot water to be turned off in apartments, and in the private sector the owner himself must take care of its availability. Water heaters can help with this. The boiler device for heating water can be very different, but the main distinguishing feature it from flow heaters - the presence of a storage tank in which there is always a supply of heated, ready-to-use water.
Boiler device for heating water - photo
Modern storage water heaters can be of direct or indirect action. Boilers as an energy source direct heating may use electricity or natural gas. In indirect heating systems, heat exchange takes place from the heating system of the house or from other sources of thermal energy (for example, solar water heaters).
Consider various schemes devices of modern boilers.
In such systems, the transfer of thermal energy goes directly to the heated one for further domestic use water. They can be electric or gas.
The layout, location, placement of inlet and outlet pipes, the control and automation system from manufacturer to manufacturer can vary significantly, however circuit diagram- one. The figure shows its general simplified view:
Electric direct heating boiler - diagram
To prevent galvanic corrosion in the water tank, an anode made of magnesium is placed in it. Its electrical potential is less than that of the tank body or the surface of the heating element, so destructive corrosion processes will affect it. Periodically, as corrosion and overgrowth occur, the anode is replaced with a new one.
Such a scheme is simple, and is the most widespread among household boilers. Such devices are usually inexpensive, which makes them popular with consumers. Main disadvantage- The heating element works directly in heated running water, which leads to a fairly rapid overgrowth of mineral deposits dissolved in it.
The gas boiler is quite simple in terms of the principle of its operation and has the following general layout:
A gas-fired boiler has a high performance, it is much more economical than an electric one. However, it also has significant drawbacks - it requires a mandatory chimney, and its installation is associated with the process of coordinating the project with the supervisory technical supervision authorities. In addition, such direct heating boilers are much more expensive than electric ones.
The main fundamental difference is heated for domestic needs ( so-called, sanitary) water does not have direct contact with electrical or gas appliances heating. Heat is transferred by connecting to the house heating system (or other sources of hot boiler water).
Such a boiler is most often installed in combination with a single-circuit heating boiler. This type of boiler can have a volume measured in tens or hundreds of liters, and which one to choose will depend on the number of households. Floor models are produced, or they are mounted to the wall horizontally or vertically on special brackets.
According to the organization of heat transfer, they can have a completely different layout:
This boiler is designed as follows:
Indirect heating boiler with a heat exchanger - a coil (sectional photo)
The coil in some models is located closer to the bottom of the tank, where cold water falls, while in others it is evenly distributed throughout the tank, which allows you to quickly heat the entire volume of liquid.
Boilers are produced, the design of which includes two heat exchanger tubes. The coolant heated by the boiler passes through one circuit, and from other possible heat sources, for example, from solar water heaters, through the second circuit.
Another version of the indirect heating boiler does not have coils with a coolant inside, but is arranged somewhat differently. It consists of two containers that are installed one inside the other. Naturally, the tank, which is located inside, has a smaller volume - it is an accumulator of heated sanitary water.
Indirect heating according to the tank-in-tank principle
The diagram clearly shows internal structure this model.
Positive qualities of indirect heating boilers:
However, there are also disadvantages:
You can learn more about the device of a boiler for heating indirect water by watching the video attached to the article:
Boilers that combine both principles are a good option. They are connected to the heating circuit, but their design also implies the presence of their own heating element. For example, a diagram of the SMART heating boiler device from ACV:
Such a boiler design is the most versatile, and combines the positive qualities of all the systems mentioned above. Perhaps the only drawback of such a water heater is the rather high price.
When choosing a water heater, consider the pros and cons of each option by looking at the characteristics of each. It is also important to pay attention to the size of the selected device and consider the place it should take.
In private houses, cottages, sports complexes and hotels, an indirect heating boiler is often used - the water heater functions without being connected to centralized water supply. This equipment copes with the heating of large volumes of water, easily maintains the desired temperature and ensures uninterrupted supply of hot flow.
In a word, if you are looking for a budget water heater in a kit for a single-circuit boiler, consider installing it in the BKN house. And to simplify the task of choosing, we suggest that you familiarize yourself with the criteria for buying a boiler, the principle of its operation and connection diagrams.
An indirect heating boiler can only operate on resources from an external source, but to service the system in warm time year, you can connect the heating element.
To ensure uninterrupted supply, a recirculation circuit is provided in the system - water will constantly move through the pipes, and when a tap is opened, a hot stream will flow at the points connected to the circuit.
An indirect heating boiler is usually installed next to the heating boiler, and this “duet” takes up a fairly large area, especially if both devices are floor-standing
Thus, the device allows you to significantly save on energy resources, but at the same time get no less comfort than when using centralized system hot water supply.
Image gallery
The rate of water heating depends on the number of turns on its spiral. The principle of operation of this design of an indirect heating boiler is extremely simple: cold water enters the tank, and the coolant, moving along the coil, heats it up to the desired temperature.
But there are also devices designed according to the “tank in a tank” scheme, where two containers of different diameters are used instead of a spiral pipeline.
The system works like this: cold water enters a smaller tank, which is heated by a hot coolant circulating between the walls of the tanks.
In such devices, water becomes warm in a matter of minutes - big square heating allows the equipment to work efficiently in flow mode, ensuring an uninterrupted supply of hot flow.
A combined BKN for heating water can use energy from several sources at once or be equipped with a built-in heating element.
By location:
Tank shape:
Depending on the nuances of use, layout features and availability free space, you can choose optimal model BKN, which will organically fit into the design of the room and provide your home with an uninterrupted supply of hot water.
One of the main parameters that should be the decisive argument when buying a boiler is its capacity. To find out the required tank capacity, we advise you to focus on the number of people in your family.
It is important to separate the concepts of "total tank capacity" and "working capacity", because the spiral pipe located inside the boiler occupies a significant area. Therefore, be sure to specify when buying how much water is actually placed in the device. In the technical specifications, this nuance should be indicated.
Also, in addition to the "total" recalculation of potential consumers, it is necessary to take into account both the frequency and volumes of water use. For example, if your family loves to soak in warm bath, and not hastily take a shower, the working capacity of the tank must be appropriate - at least 120 liters.
It is advantageous to use BKN in combination with a solid fuel or single-circuit gas boiler, but if the water flow is less than 1 l / min, a double-circuit boiler will cost less, which will take up much less space than an indirect heating system
Other important parameters:
When choosing the shape and size of the tank, it is also necessary to take into account that although theoretically the boiler can be installed in any room where there is access to the heating main, its optimal location is next to the boiler. So heat transfer is most efficient.
An indirect heating boiler can be made with your own hands. The instructions for manufacturing the unit are described in.
As already mentioned, BKN uses energy from an external source to heat water. Therefore, before connecting to the coolant, it is important to choose a suitable scheme for mounting the device. Consider the most common options.
It is necessary to mount the boiler on a prepared flat surface in the immediate vicinity of the boiler. Suspended models mounted on a concrete or brick wall, at the same level or slightly above the heating boiler.
For a floor-standing appliance, you should level the area reserved for the placement of the tank (if the floor is critically uneven, you can make a stand in the form of a podium).
An electric storage water heater, or, simply, a boiler, has long and firmly entered our lives, providing additional comfort and allowing you not to depend on public hot water supply systems. This simple device automatically maintains the required water temperature, while having a certain supply of it. Industrially produced devices have a variety of shapes, sizes and external designs. Despite the apparent differences, at their core, all water heaters have a similar design and a single principle of operation. However, when making a choice between one or another boiler model, one should not only understand how it works, but also understand the performance features of some of its components.
In fact, any water heater of this type is a large thermos with a tubular electric heater (TEN) inside, so the design of all boilers has the following elements:
When choosing a boiler, it is impossible not to notice a big difference in price even between different models of the same manufacturer. It is due, first of all, to the technology and material of manufacture of the inner tank, as well as the presence of an electronic control and indication unit.
These parameters set the convenience of using the device, as well as the duration of its service.
Cases of water heaters have both strictly cylindrical and oval and even rectangular shapes, various colors and designs. often on outside the casing is attached to a thermometer to monitor the operation of the device, as well as regulators or control elements. The material for the manufacture of housings is steel sheet or plastic.
To install the boiler, there are fasteners in the housing design, depending on the type of placement (wall or floor installation scheme). The space between the body of the water heater and the inner tank is filled with heat-insulating material - most often dense polyurethane acts as its role.
The design of the internal tank of the boiler must meet the criterion of increased corrosion resistance and at the same time withstand constant temperature changes, therefore, manufacturers pay a lot of attention to this element, developing new tank coatings and applying methods for protecting it.
Such a coating is obtained by spraying a protective layer with its subsequent firing at high temperature(up to 850 o C). Glass enamel is not capable of oxidation, therefore it does not corrode at all. In addition, its smooth surface resists the formation of scale.
Paradoxically, the main disadvantage of such a coating stems from its advantage - the high hardness of the layer is of low plasticity and over time, constant changes in water temperature lead to the formation of microcracks in its layer, which ultimately contribute to the destruction of the tank.
Manufacturers are constantly looking for new formulations for this type of coating. For example, the addition of titanium powder equalized the thermal expansion coefficients of glassware and steel, slightly improving the crack resistance of the layer. You can slightly reduce the harmful effects of temperature exposure by setting the temperature of the water in the boiler to no higher than 70 ° C, although you still have to warm up the device at least once a month to the maximum, in order to comply sanitary regulations. Another disadvantage of the glass-porcelain coating of the tank is the increased weight of the boiler. Companies that produce water heaters with tanks of this type give a guarantee on their products for no more than 3 years.
By spraying titanium powder on the inside of the tank, excellent corrosion resistance. At the same time, this type of coating has high strength and mechanical resistance, having weak points only at welding joints. The warranty for a device with such a tank is up to 10 years, which is a huge advantage, even considering its rather high cost.
Such containers are devoid of the disadvantages of the two previous elements. Stainless steel, like titanium, is able to withstand the influence of impurities in the water, as well as corrosion. It is believed that stainless steel gives water a peculiar smell and taste that appear during its heating, but this is only speculation, absolutely not confirmed. scientific research. It is known that "stainless steel" does not enter into chemical reaction with water. Manufacturers also give up to 10 years of warranty for such tanks, but they are the most expensive. Tanks made of stainless steel, as well as titanium-coated tanks are more prone to scale formation than glass-porcelain tanks, but this does not detract from their merits. In the inner tank there are pipes for cold water supply and hot water outlet, as well as an electronic heating and protection unit.
Elements responsible for heating water to a certain temperature, as well as protecting the metal of the inner tank from destruction, are installed on a metal flange, which is connected by means of a seal to the inner tank of the device.
To heat water, heating elements of various capacities are used. Depending on the principle of heating, there are:
Some models of boilers are equipped with several heaters. This design allows stepwise adjustment of heating, and also reduces the number of switching cycles for each of them (voltage surges during switching on devices affect their durability).
Together with the heating elements, a thermostat and a magnesium rod (anode) are installed on the flange. The thermostat is responsible for turning on the heating element when the water temperature drops below the temperature set by the consumer. Thermoregulators are used both of a mechanical type and electronic devices that work in conjunction with an electronic control unit. Often, the thermostat device includes a protective shutdown circuit for the heating element in the absence of water in the tank. The magnesium electrode is designed to reduce the exchange of ions of metal components inside the boiler, giving back its particles. Such a scheme reduces the effect of electron washout from structural elements and they corrode to a much lesser extent. The magnesium rod itself is destroyed quite quickly and requires periodic replacement (when thinned to 10 mm or reduced in length to 200 mm). The control and indication circuit provides additional convenience when using the water heater, having the functions of finely adjusting the water temperature, switching on heating by time, maintaining varying degrees heating depending on the time of day.
The scheme of operation of boilers is based on the principle of separation of layers of water with different temperatures. As you know, the warm layers of the liquid are at the top. Their selection from the water heater is carried out through a hot water outlet pipe, the length of which allows the use of its upper, warmest layer. Cold water, on the contrary, enters the lower part of the tank, where the water heaters are installed. In addition, a divider is installed on the short inlet pipe, which does not allow the liquid to flow in a jet and thereby contribute to the mixing of warm and cold water.
The feature of warm liquid rising up will not allow the use of a boiler vertical design, placing it parallel to the ground. You should pay close attention to this when choosing the type of device for your needs.
Heating of cold water is carried out by heating elements (one or more). The thermostat monitors its temperature. When the set temperature is reached, it opens electrical circuit heater power supply.
Good thermal insulation allows you to maintain the desired temperature of the water, spending a minimum of energy on its constant heating.
In the case of using several heaters, one heating element is used to maintain the temperature at a given level. The rest are turned on at high consumption, repeatedly increasing the heating power. This scheme increases the efficiency and reliability of the device.
Selected from above warm water is constantly replaced by a newly heated liquid, which is supplied from the line. This is how the continuous heating process works. With a high flow rate, the temperature of the water at the outlet of the boiler drops over time, so it is necessary to choose the volume of the storage tank based on the size of the hot water intake.
It is possible for the thermostat to fail, in which case the water may boil, as a result of which the pressure in the internal tank rises to a dangerous level. To prevent an accident, a safety valve is installed on the cold water supply pipe - when the pressure limit is reached, it opens, thereby dumping part of the liquid into the supply line. The same valve is used to drain water from the device during maintenance work.
A detailed video on the boiler device is presented below:
Do not neglect periodic preventive measures consisting in cleaning the boiler from scale and rust. They will allow the device to work reliably and efficiently, as well as save you from unplanned expenses.
At the present time, autonomous hot water supply in apartments and private houses is becoming more and more popular. Centralized hot water supply has become expensive and uneconomical, which is why it is gradually becoming a thing of the past. It is being replaced by water heaters of various designs, the most common of which are storage-type devices. In this article, we will just consider the device and principle of operation of a boiler for heating water.
At the moment, there are several varieties of units for autonomous hot water supply. All of them were created with the same goal, but they achieve it in different ways, that is, using different energy carriers. The homeowner has the opportunity to choose the one that best suits him in all respects.
So, the following types of heating boilers are offered on the modern market:
Note. Directly translated from English word"boiler" means "boiler". This means that they include not only storage, but also all kinds of instantaneous water heaters. Not taking them into account will be incorrect in relation to users.
This is the most common type of hot water heater, most often used in apartments and small private houses. The reason for this popularity is the relatively low cost and ease of installation, which does not require any permits. The devices are quite reliable in operation and meet most of the requirements of users. To understand the principle of operation of a water heater, consider its device, shown in the figure:
The unit is a tank, usually round or oval, enclosed in a layer thermal insulation material(usually - polyurethane foam), covered with a decorative casing. The container itself can be made of the following materials:
An electric heating element located at the bottom of the tank heats the water to a temperature limited by a thermostat. Its maximum value, adopted in all electric boilers, is 75 ºС. While there is no water intake, the device of the electric boiler provides for maintaining the set temperature in the mode of automatic switching on and off of the heating element. The latter has additional protection against overheating and in an emergency will automatically turn off when the water temperature reaches 85 ºС.
Note. Optimal mode work for the boiler is heating up to 55 ºС. In this mode, the device provides right amount hot water and at the same time saves energy. Unfortunately, often the storage water heater operates at maximum power due to the fact that in winter time too cold water comes from the water supply and the heating element does not have time to warm it up in the economy mode.
Water intake occurs through a tube led to the upper zone of the tank, where the water is the hottest. At the same time, drink cold water provided in the lower part of the boiler, where the heating element is installed. To protect steel tanks from electrochemical corrosion, the water heater device includes a magnesium anode. Over time, it collapses, and therefore requires replacement approximately 1 time in 2-3 years.
These devices do not produce thermal energy on their own, although some models have a built-in heating element to maintain the water temperature in different situations. In normal mode, the boiler prepares water for hot water supply, heating it with a coil with a coolant flowing through it. The diagram below shows the device of an indirect heating boiler:
A large-capacity insulated tank (sometimes up to 1000 l) has a built-in coil with a coolant supplied to it from the boiler. As in an electric boiler, cold water is supplied to the bottom of the tank, hot water is taken from the top. The unit is able to provide a significant consumption of hot water, and therefore is used in private homes with a large number consumers.
The usual exchange of heat between media with different temperatures is the principle of operation of an indirect heating boiler. But in order to get water from a tap with a temperature of 55 ºС, the boiler must heat the coolant to at least 80 ºС, this is one of the disadvantages of this water heater. The second drawback is the long loading time of a large-capacity tank, so that in the case of intensive water consumption, people living in the house need to adapt to use the hot water supply according to a certain schedule.
Like electric boilers, indirect heating water heaters are equipped with a magnesium anode to protect the steel tank from corrosion. More complex and expensive models are equipped with two coils, the coolant from the boiler flows through one, and the second can be connected to an alternative source of thermal energy. They can serve as another boiler or solar collector. To maintain the temperature in different situations, a heating element with a thermostat is built into the upper zone of the tank.
Indirect heating units are produced in wall and floor versions, they can work with any source of thermal energy. Manufacturers of boiler equipment often offer them in conjunction with double-circuit boilers. In this case, the heat generator maintains the heating temperature and loads the boiler, alternately switching between these two systems.
These devices are structurally and externally reminiscent of electric boilers. All the same tank hung on the wall, covered with a layer of insulation, only a gas burner is installed at the bottom, and at the top there is a chimney pipe. A gas boiler works on the same principle, only a burner that heats a container of water serves as a heat source. The water heater device is shown in the diagram:
As can be seen in the figure, heating is carried out not only from the burner, but also by taking heat from the combustion products. This is achieved by a steel flue with dividers, passing vertically through the tank and exchanging heat with water. The operation of the burner is controlled by an electronic unit, whose task is to extinguish or ignite it when the set temperature is reached or lowered. As usual, the design of the boiler provides for a magnesium anode to protect the body.
This type of water heaters is not very popular due to the difficulties in designing and connecting gas-using installations. In addition, to operate a gas boiler, you will need a full-fledged chimney; it is not always possible or too expensive to fulfill this requirement.
The advantage of storage water heaters is that they can immediately produce a large flow of water for hot water supply, but for a limited period of time. After that, they need a break to prepare the next portion of water.
Unlike storage boilers the principle of operation of an instantaneous water heater is not to heat up in advance, but to quickly warm up running water as needed.
Heat sources are the same electric heating elements and gas-burners, they only turn on after the hot water tap is opened in the house. These heaters include:
Note. Sometimes a plate boiler is used to provide hot water to a private house, which is a water-to-water heat exchanger. Like an indirect heating boiler, it transfers the energy of the coolant to water, only it does it in flow mode.
The design of the geyser is quite complex, and therefore deserves a separate topic. An electric water heater is simple: a powerful heating element heats running water in it. Having such an advantage as small size, the device has too high power consumption and therefore its scope is limited. The device of a flowing electric boiler is shown in the figure:
The advantage of flow-through water heaters is that they can supply heated water without preparation and for an unlimited time. But its consumption has limits, which is important when in large numbers consumers.
If we distribute all the listed devices by popularity, then electric boilers will confidently take the first place, the reasons for this are understandable. In second place are geysers, the third is for indirect heating boilers.
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