Description

They can also use a working environment with a high pH value. In conventional water heaters, hard water leads to the following problems:

• Scale deposited from hard water on the surface of the heating element reduces its heat transfer. Over time, it can reach such a thickness at which the element may fail due to overheating.
• Water with a high pH causes local (pitting) corrosion of the heating element, which also subsequently leads to its burnout.

Advantages

Ceramic elements are free from the disadvantages typical of metal elements in hard water. They have the following advantages over the latter:

• increased efficiency of heat transfer of the working fluid;
• high operational reliability;
• good maintainability;
• no slagging in hard water.

The ceramic electric heater is placed in a housing in the form of a tube made of stainless material. In the VET water heater there is no contact with hard water, so scale does not form on it, and it is not exposed to the aggressive properties of the working environment. Replacing it is an easy operation. It is simply removed from the tube body and inserted back. Total surface area pipe bodies the inside of the tank is large. It is such that for 1 sq. cm it accounts for no more than 1.2 watts of power. Therefore, even for the hardest water there are no conditions for scale formation.

The body of the storage tank (cylindrical tank) and the pipe shells of the heating elements are made of stainless steel food grade 12Х18Н10 (AISI304).

All units are equipped with automatic temperature control, controlled via remote control. You can use it to perform the following operations:

• Set the temperature to be maintained;
• Monitor the temperature visually using the built-in discrete type indicator (this sensor is available on all models for hard water);
• Provide protection against overheating;
• Block turning on an empty device;
• Enable installation in manual mode.

Technical parameters of water heaters for hard water VET

• Volume – from 300 to 10000 l;
• Power – from 3 to 300 kW;
• Maximum pressure: working – 0.6 MPa, test – 1.0 MPa;
• The service life of the tank and pipe heat exchangers is from 10 to 25 years.

Study of the design of electric heating installations and the rules of their operation.

Electric heating has a significant technical advantage: constant readiness for operation of electrothermal installations, the ability to fully automate heating processes while maintaining the temperature within established limits (in incubators, pasteurizers, etc.), low capital costs, good sanitary and hygienic conditions. In practice they use various ways electric heating: resistance, induction, electric arc, dielectric, electron beam, infrared rays.

Electrical resistance heating has found widespread use in agricultural production. This method uses thermal effect electric current. Walking through solids(conductors) or liquid media, electric current heats them.

Resistance electric heating units come in direct and indirect electric heating. With direct electric heating, the conversion electrical energy into heat occurs as a result of the passage of electric current directly through the heated medium (water, milk and other conducting media). With indirect electric heating, an electric current passes through a special heating element, from which heat is transferred to the heated medium.

In installations with direct (electrode) heating, the heated medium is placed between the electrodes, which are connected to electrical circuit AC. Electric current flowing through the medium between the electrodes heats it. Installations with direct heating are called electrode heaters.

In animal husbandry electrode heaters Mainly used for heating water. Electrode water heaters are simple in design and easy to use. The main disadvantage is a significant increase in power consumption from the beginning of heating water to the end (about five times when heating water from 10 to 100 ° C). This is explained by the fact that as the temperature of water increases, its resistivity decreases. Another disadvantage of these heaters is the direct contact between the electrodes and the medium (water), which increases the risk of injury electric shock people and animals.

In installations with indirect (elemental) heating, heat is released when current passes through the heating elements. Installations with indirect heating are called elemental.

Heating elements are made in the form of a tape or wire from a material with the following physical and technical properties: large resistivity, high temperature melting, low temperature coefficient of resistance, oxidation resistance.

For the manufacture of heating elements they use; nichrome, fechral, ​​constant and other conductor materials.

Heating elements can be open or closed.

Enclosed heating elements do not have direct contact with the heated material. In practice, a tubular electric heater (TEH) is widely used. It is a metal tube, inside of which there is a spiral of nichrome or constantan wire in quartz sand or fused magnesium oxide. The tubes are sealed. The service life of the heating elements is about 10,000 hours.

Let's look at the design and operation of some types of electric heaters.

Designed to heat water to a given temperature (from 8 to 90°C) and keep it hot. They consist of a welded steel tank with a capacity of 200 to 1600 liters, a casing with a lid, a heating device, and a temperature relay. Between the casing and the tank there is a thermal insulating layer 3 made of glass or slag wool. Water heaters are equipped with a control station with an automatic switch and a magnetic starter.

A – device; b – electrical diagram; c - temperature relay; 1 – casing; 2 - reservoir; 3 – thermal insulation; 4.7 – pipes; 5 – temperature relay; 6 - heating device; 8 – drain valve; 9 – insulating insert; 10 – thermometer; 11 – mercury switch; 12 – L-shaped finger; 13 – clip; 14 - bimetallic spiral; 15 – roller; 16 – tube; 17 – counterweight; 18 – stop; G1 - switch; G2, G3, G4 – fuses; TO - magnetic starter; T – thermostat.

The heating device consists of several tubular electric heaters (heaters) powered by a 220 V network.

The temperature relay is used to automatically turn on and off the heating device depending on the water temperature. It consists of a bimetallic plate spiral, one end of which is attached to the body, and the other is connected to a roller and a mercury switch mounted on the roller. Before turning on, the water heater is filled with water; until it flows through the collapsible pipe. Then press the start button of the machine. Through the closed contacts of the temperature relay, the coil of the magnetic starter is turned on, which, in turn, turns on the tubular electric heaters. As the water heats up, the coil twists and turns the L-shaped pin, which tilts the mercury switch. When the water temperature reaches the upper preset limit, the mercury switch will turn so that the mercury in it flows to one side, and the magnetic starter coil circuit will open, and therefore the heating elements will turn off. As the water cools, the temperature relay also cools, which will turn on the magnetic starter and heating elements again.

The required water heating temperature is set using the temperature relay scale. When you turn the lever clockwise, the set heating temperature increases, and when you turn the lever counterclockwise, it decreases. The water heater is connected to the water supply network through a rubber hose (insulating insert) 9 with a length of at least 1 m. The rubber hose serves to electrically insulate the water supply from the water heater. When commissioning, the water heater is filled with cold water by opening the valve on the supply pipe. As soon as water flows from the pipe hot water, close the valve on the supply pipeline and turn on the heating device to the network.

Hot water is taken from the tank through the pipe, having first opened the valve on the supply pipeline. When the valve is open, cold water from the water supply flows through the pipe cold water into the reservoir and displaces the heated water through the hot water pipe. As a result, the tank is always full of water.

Heated water cannot be disassembled through the drain valve when the heating device is turned on, since the water level in the tank may drop below the heating elements and the latter, heating without water, may fail. Therefore, you can turn on the heating device to the electrical network only when the tank is filled with water.

VET type water heaters are designed to be supplied with water from the water supply network with a pressure of no more than 300 kPa. The water heater is installed on a pedestal made of brick or wood. Its body must be grounded or zeroed. The water heater can be powered from an alternating current network with a voltage of 380 or 220 V. If the network voltage is 380 V, the heating elements are connected in a “star”, with a network voltage of 220 V they are connected in a “triangle”. Electric water heaters-thermoses VET-200, VET-400, VET-800, VET-1600 have this design.

Designed to heat running water during its immediate consumption. Water can be heated to any given temperature within a range of up to 90°C.

An instantaneous water heater of the EVP type is a cylindrical tank covered with a metal casing designed for thermal insulation and enclosure hot surface tank from touch. Inside the tank along its axis there are three tubular heating elements, which can be connected in a “star” or “triangle” depending on the network voltage. A lid is placed on top of the tank with rubber gasket. The lid has six holes for exiting the ends of the heating elements. The water heater is connected to the water supply network using insulating rubber hoses (inserts) each 1 m long. Cold water from the water supply is supplied to the tank through tap 6 and the lower (inlet) pipe, washes the heating elements, heats up and leaves the tank through the upper pipe. The heating temperature depends on the amount of water flowing through the water heater per unit time. The more water flows, the lower its temperature will be. Therefore, the temperature of the heated water is controlled by a valve, reducing or increasing the water supply to the tank.

A thermometer and a safety valve are installed on the upper branch pipe, which serves to prevent the possibility of an explosion during intense steam formation (for example, in the event of a cessation of water flow). To turn on the water heater, you need to open the valve and let water from the water supply into the tank, and then connect the heating elements to the electrical network.

The automation circuit of the EVP-2A water heater allows for two-position control of the outlet water temperature. Instantaneous electric water heaters of the EVP type are produced by industry in various modifications.

In addition to the considered electric water heaters, electric heaters UAP-1600/0.2, EV-F-15A, UAP-300/0.2-M1, UAP-400/0.9-M1, etc. are used on livestock farms.

Electric heater installations designed for heating air in systems supply ventilation livestock, poultry and other agricultural premises. They can also be used for drying various materials, grass, hay, grain, etc. Air heating in electric heaters is carried out by tubular heating elements finned with aluminum. Open heating elements are also used. Heating elements are installed in the heating chamber along the path of air movement. The number of heating elements regulates the power (heating capacity) of the electric heater installation. The temperature of the heated air with a constant number of elements can be changed by varying the fan performance.

Our industry produces electric heating units of the SFOA series. These installations are simple in design, compact, easy to operate, and can be easily automated.

The electric heater installation (Fig. 90) consists of an electric heater, a centrifugal fan, an electric motor 6 and a cabinet with equipment automatic control. For agriculture, air heaters are produced with a power of 5 to 100 kW for a voltage of 380/220 V. Electric heaters of other types are also produced (NEK-V1, 1SFO-18/0.5T, EK, EKVidr.).

Electric brooders Designed for local heating of chickens in the first month of their rearing when kept on the floor.

Electric umbrella brooder BP-1 consists of a pyramidal hexagonal umbrella, a heater, a temperature relay and a suspension.

The heater is a truncated cone, on the side surface of which four tubular electric heaters of the heating element type are installed, connected in pairs into two groups. The power of each element is 300 W at a voltage of 110V. The set temperature value under the umbrella is maintained using a thermostat, which consists of a membrane sensor filled with ether, an intermediate relay, a microswitch, an adjusting screw with a shutdown mechanism and a toggle switch for turning the lighting lamp on and off. To monitor the operation of the heating elements of heating elements, a signal lamp I is used.

When the electric brooder is turned on, current from the network through the contacts of the temperature relay enters the coil of the intermediate relay and through its contacts to the heaters (heaters). If the set temperature is exceeded, the contacts of the temperature relay open and the heating elements and warning lamp are turned off. When the temperature under the brooder drops, the temperature relay is activated and turns on the heaters with a signal lamp. Brooders are suspended from the ceiling of the building. As the chicks grow, the brooder is raised using a winch. The BP-1 electric brooder consumes a power of 1.2 kW and is designed for a voltage of 220V.

Electrically heated floors are becoming increasingly popular wide application on livestock and poultry farms. They improve the indoor microclimate and protect animals from colds. The floors are heated with heating wires or galvanized steel wire. For these purposes, wires of the POSKHV and POSKHP brands are used.

When installing a floor (clay or concrete), waterproofing made of roofing felt or polyethylene film is laid in two layers on good compacted soil. Thermal insulation is laid on the waterproofing (if the floor is concrete), covered with sand. Foam concrete, polystyrene foam, expanded clay or boiler slag are used as insulation, which is poured in a layer up to 150 mm thick. Concrete is placed on the thermal insulation. Heating wires are laid in a layer of concrete, on top of which a shielding metal mesh is placed. The thickness of the concrete layer can range from 60 to 200 mm, depending on the mechanical load on the floor and the electricity supply schedule. With frequent power outages, the thickness of the floors is increased to increase their heat storage capacity. With an uninterrupted supply of electricity, the thickness of the concrete layer is made no more than 60 mm, the thickness of the layer under the heating wire is about 40 mm. When installing an adobe floor, sand is poured onto the waterproofing in a layer of about 100 mm, in which heating wires are laid in a zigzag. A screening mesh is laid on the sand and then a clay-straw mixture or clay concrete. The shielding mesh is grounded or neutralized. The floor heating device is divided into several sections with independent control.

Depending on the age of the animals, the floor temperature is maintained within certain limits using a two-position temperature sensor or relay.

Page 44 of 59

Chapter 19. ELECTRIC WATER HEATERS AND BOILERS

HOT WATER SUPPLY SYSTEMS WITH ELECTRIC HEATING WATER

Electrical water heating is one of the cost-effective uses of electrical energy in agriculture. Electric heating of water in livestock farming is especially common for technological purposes (feed preparation and watering of animals, receiving and processing of products, washing equipment, etc.), veterinary, sanitary and hygienic needs, space heating, etc. The consumption of hot water for individual processes and operations is established by standards technological design of agricultural enterprises (NTP-SH) and building codes and rules (SNiP).
The spread of electric water heaters is facilitated by the simplicity of design and maintenance, ease and accuracy of automation, and constant readiness for work. Thanks to this, labor costs for producing hot water and steam are reduced tenfold, especially on small livestock farms that do not have their own fire boiler houses.
Installations for electric water heating are classified: by type: water heaters and steam generators; degrees of centralization: local (individual) and centralized;
power consumption mode: according to a free schedule and before a scheduled schedule (heat storage);
working pressure: atmospheric pressure, low pressure(up to 6-105 Pa), high pressure(over 6-105... 106 Pa);
principle of operation: non-flowing (capacitive), flowing (fast-acting).
Centralized hot water supply installations have increased capital costs and reduced thermal efficiency. These installations are universal and are used in large farms, where a large amount of hot water is consumed for a variety of needs. However, their use requires a fairly convincing feasibility study.
On the contrary, local hot water supply installations are simpler in design, easily automated, and have increased efficiency. They are used, as a rule, to produce hot water for one or more purposes (for example, watering calves, washing milk flasks, etc.) .
Instantaneous water heaters provide hot water immediately after switching on, but have a high installed thermal power. Turning them on during peak hours requires additional power transformer substations. Non-flowing water heaters with combined or separate hot water storage tanks have less power; they can be turned on during dips in the daily load schedules of substations, ensuring full load electrical networks and substations throughout the day.
Thermal power water heater is determined by the maximum estimated hourly consumption of hot water from the daily water consumption schedule. This schedule is constructed based on specific water consumption rates and water consumption patterns during the day. At the same time, hot water different temperatures usually prepared by mixing with cold.

ELEMENTAL WATER HEATERS AND BOILERS

Elemental water heaters are usually made with hermetic tubular electric heating elements (TEHs). The advantages of these water heaters include: increased electrical safety, lack of water pollution and constant power.
Basically, elemental water heaters are made individually to supply water to small, scattered consumers.
They are made as flow-through and capacitive, operating at atmospheric pressure. On livestock farms, capacitive water heaters of the VET type (electric water heater - thermos) are widely used, designed to heat water up to 90°C, used in dairy, washing, milking areas and so on.

Rice. 19.1. Electric thermos water heater VET-200:
I - insulating insert of the cold water pipeline; 2 - drain valve; 3 - casing; 4 - cross; 5-reservoir; 6 - heater; 7 - temperature relay; 8-mineral wool; 9 - collapsible pipeline.
They are manufactured with a capacity from 200 to 1600 liters and a power from 6 to 33 kW.
The VET-200 water heater (Fig. 19.1) has a tank with spherical bottoms and an outer tin casing, between which is laid thermal insulation. The heating device consists of tubular elements connected in a “star” when powered from a 380/220 V network.
Water is supplied through a float piston valve, which automatically maintains a certain filling level in the tank. The set water temperature is maintained automatically using a dilatometric thermostat.
Tankless water heaters are compact and fast. In agricultural production, the electric instantaneous water heater EPV-2A is common (Fig. 19.3). Water is heated by three heating elements installed in a cylindrical heat-insulated housing 2. The total power of the heating elements is 12 kW.
At a water heating temperature of 90°C, the productivity of the device reaches 120 l/h, which is enough to satisfy the need for hot water, for example, a barn for 100 heads.

The temperature of the heated water is controlled by the degree of opening of the valve on the supply pipeline 8 or automatic switching on and turning off elements at a given water flow. To avoid overheating of heating elements 1, water must continuously flow through the apparatus. To prevent the possibility of an explosion during intense steam formation (for example, in the event of a cessation of water flow), a safety valve pressure 5. Heating of running water. An example of the effective use of elemental water heaters are electric water heating systems for watering animals and poultry. According to zootechnical requirements, the water temperature in drinking troughs should be: for cattle not lower than + (5... 7) ° C, for laying hens + (10 ... 13 ° C).
In addition, heating water in circulation systems necessary to prevent pipelines from freezing in winter in unheated rooms.
The water heater VEP-600 (Fig. 19.4) is designed for heating drinking water in barns for up to 200 cows with tethered housing. It can also be used to heat water up to 80°C, used for technical needs. The power of the heating elements is 10 kW. The water heater includes a flow-through heating tank 4 with a safety valve 6, a thermostat 7 and a thermometer 8. Water circulation in the system is carried out using a pump 9. The installation kit includes a control cabinet. The temperature of the water at the outlet of the heater is regulated by a thermal relay, and the cyclic operation of the pump automatically ensures that the set water temperature is maintained using a thermal relay installed in the coldest zone of the drinking system.

Rice. 19.4. Electric water heater VEP-600:
1 - insulating inserts; 2- heating block; 3- check valve; 4 - tank; 5 - control cabinet; 8 - safety valve; 7 - thermal contactor; 8 - thermometer; 9- pump.

When cattle are kept free-stall, special group automatic drinkers with electrically heated water of the AGK-4 type with a power of 1 kW are used.

Elemental boilers are designed to produce water at about 100°C (boiling water). Boiling water is necessary for sanitary and hygienic needs in utility rooms production facilities(on farms, in vegetable warehouses, workshops and laboratories). Elemental boilers are especially common in catering establishments.
Boilers continuous action(Fig. 19.5, a) work on the principle of communicating vessels: one vessel is the body of the boiler 2, the other is the nutrient tank 7, installed next to the body.

Rice. 19.5. Schematic design (a) and electrical diagram (b) of a KNE elemental boiler:
K1 - relay; K2 - magnetic starter; T - transformer; R1 - resistor; Hi, H2 - signal lamps; VI... V4 - diodes; E1, E2, E3 - heating elements; F1 - fuse; S1 - switch; E4, E5 - “dry running” electrode sensors.

Both vessels are connected to each other by a supply pipe 3.

The body of the boiler is divided into two halves, the upper of which serves as a collecting tank for boiling water 9, and in the lower there are heating elements 11 for preparing boiling water.
The body is divided by a partition-diaphragm 10 with an overflow tube 8 connecting both parts of the boiler.
The boiling water collection contains collapsible crane and steam outlets 4. The top of the tank is closed with a lid.
The nutrient tank contains a hollow float ball 6, which regulates the flow of cold water using the nutrient valve 5.
When the heating elements are turned on, as the water temperature rises, steam bubbles formed during boiling carry the water upward; seething begins in the overflow pipe, while the water level rises and boiling water overflows over the edge of the overflow pipe into the boiling water collection.
Boilers of the KPE type are produced with a capacity from 25 to 100 l/h and installed capacity Heating elements from 3 to 12 kW.
The electrical circuit of the boiler (Fig. 19.5.5) provides for the protection of heating elements from “dry running” and automatic maintenance of the water level in the boiling water collector using electrode sensors E4 and E5. One of the electrodes of the E4 sensor is located in the supply tube at the immersion level of the heating elements, and the other two are installed in the boiling water collector, corresponding to the upper and lower boiling water levels. Lamp H2 signals the operation of heating elements, and H1 indicates that the boiler is connected to the network.
To prevent corrosion and scale formation on heating elements, the boiler is washed daily after finishing work. cold water. This creates a “thermal shock” (turn on the heating elements without water for 2...3 minutes, followed by rinsing with cold water). As a result of cooling, the geometric dimensions of the heating elements change sharply, and scale is separated from their surface.

Equipment

The price includes the delivery set: thermal insulation in a practical casing made of PVC or ABS plastic, one or more heating elements (Austria, Poland). You can also purchase additional compatible equipment to equip the water heater. The price list is available at the link: additional equipment ›.

The thermal insulation that water heaters are equipped with serves to reduce heat loss and reduce energy consumption to maintain the water temperature inside the tank at a given level. The water heater is supplied with a casing and thermal insulation in assembled form, with the exception of models with a volume of 4000 liters or more. Thermal insulation, if necessary, can be easily dismantled and installed to carry the device through doors and mounting windows. Electrotherm products come with two types of thermal insulation: polyurethane foam in a soft PVC fabric casing or polyester in a hard ABS plastic casing.

Development of custom equipment

By special order it is possible to manufacture a water heater of any volume in the range from 600 to 10,000 liters. At your request, consultants will select a sufficient volume and power of the water heater, based on the estimated hot water consumption at the site.

In addition, at the request of the customer, additions and changes can be made to the design of the water heater, for example: changing overall dimensions, changing the location of the pipes, increasing the operating pressure and electrical power.

You can find out more about the development of a custom-made water heater.

Application and features

The Electrotherm 1000 E electric water heater is a thermally insulated sealed tank, the water in which is heated using one or more electric heating elements made of stainless heat-resistant steel. The heating elements are equipped with thermostats and allow you to regulate the water heating temperature. Also, heating elements are equipped with emergency temperature sensors that protect the water heater from overheating. Structurally, the water heater allows you to organize recirculation of hot water in the DHW system.

Industrial electric water heaters are used for hot water supply (DHW) systems of municipal and commercial facilities that have a need for large quantities hot water: hotels, schools, kindergartens, hypermarkets, sports complexes, factories, etc. Water heaters are used as the main or as a backup source of hot water supply.

The performance of electric water heaters depends on their volume and electrical power. The volume of standard electric water heaters of the E series ranges from 600 to 10,000 liters in the standard version. The power of the water heater in standard models ranges from 4.5 to 90 kW. By special order, the volume and power of the water heater can be changed up or down.

The internal tank of the product is made of high-quality AISI 321 stainless steel or high-strength structural steel with ceramic coating and is designed to operate under excessive internal pressure.

HONEST CAPACITY: unlike a number of other manufacturers, in electric water heaters Electrotherm capacity of the internal tank is not underestimated. This means that in the 1000 E model the actual capacity is 1000 liters. At the same time, models from a number of other manufacturers

(both Russian and European) marked xx1000 may actually have a smaller capacity, for example 700-800 liters. Thus, manufacturers achieve an apparent reduction in the cost of products, although in fact they reduce the real performance of water heaters.

Differences between types of Electrotherm internal tanks

High strength coated structural steel inner tank

Steel thickness from 3 mm, inner covering consists of ceramics with special components. The coating reliably protects the internal tank from corrosion and is resistant to deformation. Coated water heaters are used for heating and storing drinking water, water for sanitary needs (showers, laundries, swimming pools, etc.) and water for technical needs, which is confirmed by the corresponding expert opinion.

The outside of the tank is covered special paint, which has water-repellent properties, serves to protect the tank from aggressive environmental influences and from external mechanical damage during transportation and connection.

Internal tank made of high-strength structural steel without coating

Steel thickness from 3 mm, containers with a tank made of structural steel are used in closed systems heating as a heat accumulator (buffer tank) and in ventilation systems as a cold accumulator. The outside of the tank is coated with a special paint that has water-repellent properties and serves to protect against external influence corrosion, and external mechanical damage during transportation and connection.

Interesting fact: the exterior paint is from the same manufacturer as the Eiffel Tower in Paris and the Golden Gate Bridge in San Francisco.

Stainless steel inner tank

Stainless steel water heaters are used for heating and storing drinking water, water for sanitary needs (showers, laundries, swimming pools, etc.) and water for technical needs. Stainless steel is used for manufacturing European production(France, Finland) grade AISI 321 with the addition of titanium because it has better anti-corrosion properties than the traditionally used AISI 304 and AISI 304L steels.

Why is the country of steel production important: the properties of stainless steel are determined by the content of alloying additives (mostly chromium and nickel), which give the steel anti-corrosion properties. In European steel, the content of alloying additives is higher, and the steel has stronger anti-corrosion properties, in comparison with some types of Russian steel, where, to reduce the cost, a minimum amount of alloying additives is used at the lower limit of the standard.

All types of water heaters undergo overpressure testing

Every manufactured water heater undergoes testing. Test pressure up to x2 of the nominal operating pressure. This means that water heaters with a working pressure of 6 bar are tested at a pressure of 12 bar, which confirms the exceptional reliability and quality of the equipment

High reliability Electrotherm water heaters are due to the careful selection of materials and the use of welding equipment and original filler materials from leading European concerns.

You can learn more about the advantages of Electrotherm products.

Study of the operation of elemental water heaters

To ensure hot water Agricultural production facilities have found widespread use of elemental water heaters. In elemental water heaters, water is heated through heat transfer from hermetic heating elements (heating elements) placed in the heated water. Depending on the operating mode, it is customary to distinguish between capacitive (non-flowing) and instantaneous water heaters.

Three-phase capacitive elemental water heaters are widely used in agricultural production. These include water heaters of the following types: VET (electric thermos water heater), UAP (universal automatic heater), SAOS (resistance heating, battery type, open hot water supply system), SAZS (resistance heating battery type closed system hot water supply).

Basic technical specifications elemental cylinder water heaters are given in Table 2.1.

IN general case elemental capacitive water heaters consist of a water tank, a protective casing, a layer of thermal insulation located between the tank and the casing, one or more heating elements, one or two temperature relays, hot and cold water pipelines.

Table 2.1 - Technical characteristics of capacitive element water heaters.

Water heater type.	Capacity, l	Rated power, kW	Heating element power, kW	Maximum water temperature, °C	Heating duration, hour
UAP-400		12,0			3,3
UAP-800		18,0	2,0		4,5
UAP-1600		30,0	2,0		6,0
SAOS-400, SAZS-400		12,0	2,0		3,5
SAOS-800, SAZS 800		18,0	3,0		5,0
SAOS-1600, SAZS-1600		31,5	3,5		5,3

Water heaters of all types are connected to three-phase network voltage 380/220 V, frequency 50 Hz.

Electric water heaters of the VET type are widely used for heating water consumed for various technological needs in livestock farming, workshops, garages, and public utility enterprises. Water heaters Tina VET - 200, VET - 400 are equipped with one, and VET - 800 and VET - 1600 are equipped with two heating devices and two thermostats.

Water heaters UAP - 800 and UAP - 1600 operate with three power levels, determined by the ratios 1: 2/3: 1/3 and the corresponding three operating modes - forced heating, battery operating mode and heating 1/4 of the volume.

Water heaters of the SAOS and ECCS types are designed for heating water in hot water supply systems of livestock farms (washing dairy equipment, preparing feed, etc.), garages, maintenance points and public utility enterprises.

Water heaters flow type differ in compactness and speed. In agricultural production, instantaneous water heaters EPV - 2A and EF - F - 15 are common. The main technical characteristics of instantaneous element water heaters are given in Table 2.2

Instantaneous elemental water heaters are designed to heat running water used for technological needs for heating premises.

Table 2.2 - Technical characteristics of instantaneous element water heaters.

Instantaneous electric water heaters operate only on a free schedule, that is, water is collected or heated throughout the day as it is consumed.

An example of a capacitive water heater is “POLARIS”, and a flow-through element water heater is “GAMMA - 5”. The “POLARIS” cylinder water heater is designed to provide hot water supply and has the following characteristics:

2. Tank volume - 50 liters;

3. Rated power - 1.5 kW;

4. Maximum working pressure- 8 atm.;

5. Heating time from 20 °C to 65 °C - 2.45 hours;

6. Weight - 16kg.

The water is heated by a heating element located at the bottom of the tank. When hot water is consumed, cold water entering the bottom of the tank displaces heated water through a tube at the top of the tank into distribution network hot water. During heating, the signal lamp lights up. When the set temperature is reached, the thermostat disconnects the heating element from the network. The temperature indicator shows the water temperature at at the moment time. When the temperature drops, the water heater turns on automatically.

The water heating temperature can be adjusted by rotating the thermostat adjustment screw with a screwdriver (to do this, you need to remove the plastic cover under the tank).

The instantaneous water heater "GAMMA -5" is designed for quick heating of cold water and has the following technical characteristics:

1. Rated voltage- 220 V;

2. Maximum power - 5 kW;

3. Minimum permissible pressure - 0.2 atm.;

4. Maximum productivity - 4.0 l/min;

5. The maximum outlet water temperature is 40 °C.

The instantaneous water heater operates automatically.

The electrical diagram of the water heater is shown in Figure 2.1.

Figure 2.1 -Electrical diagram instantaneous water heater

SP - pressure switch; SK - thermostat contact; SA1, SA2 - power switches; EKl, EK2 - heating elements; HL1, HL2 - light indicators.

The water heater automatically turns on when the inlet valve opens and the switches turn on, and vice versa, it turns off when the valve closes and the switches turn off.

The outlet water temperature is adjusted by changing the position of the valve head. You can adjust the water temperature using two-position switches:

1. The first switch is turned on - minimum heating (2 kW);

2. The second switch is turned on - medium heating (3 kW);

3. Both switches are on - maximum heating (5 kW).