Electric boilers

Electric boilers are closed containers that are used for water heating (for bath, shower, sink, other daily living needs). Electric boilers (electric storage water heaters) can be mounted in houses, flats, hotels, restaurants, shops, supermarkets, offices, pensions, etc. with central heating system or water heating vat.

Benefits of electric boilers:

  • Quick preparation of hot water.
  • Precise water temperature control.
  • Easy installation and connection.
  • Protection against water overheat or freezing.
  • Protection against corrosion.
  • Economy of heat and money (hot water on demand).
  • Safe exploitation.
  • Comfortable, easy handling.

Famous electric boilers manufacturers:

Druzstevni zavody Drazice-strojirna, s.r.o. – Czech manufacturer that has been manufacturing, selling and exporting electric boilers for more than 40 years. The company provides enameled steel electric boilers in volumes 10-1000 litres. The boilers are made of quality and eco-friendly materials that ensure protection against corrosion, low thermal loss, economical exploitation and minimal environment pollution.

The company offers these types of electric boilers:

Suspended vertical electric boilers (rounded, square, small volumes up to 20 litres, non-pressure, pressure) – these water heaters can be suspended on the wall and have volumes up to 200 litres. The temperature ranges from 0 °C to 80 °C. The boilers have very low thermal loss.
–  Horizontal electric boilers – these water heaters can be mounted on the wall with suspensions or attached to any appropriate construction. The boilers have volumes of 100-200 litres. The temperature ranges from 0 °C to 80 °C.
–  Stationary electric boilers – these water heaters can be placed on the floor and have volumes of 100-1000 litres. The temperature ranges from 0 °C to 80 °C.

The Bosch Group (Robert Bosch GmbH) – German technology-based company that was founded in 1886. The company provides a wide range of products and services (automotive, household, security, packaging, heating and hot water). The products can be characterized as eco-friendly, quality, economic, convenient, efficient, advanced.

The company offers these types of electric boilers:

o   PowerStar electric tankless boilers – these water heaters operate only when hot water ir needed, have low electricity costs, save space (compact).

o   PowerStream electric tankless boilers – these water heaters are compact and leightweight. The boilers and can be installed almost anywhere inside the house (save water when installed closer to the fixture).

Gorenje Group – Slovenian manufacturer that was founded 60 years ago. The company is one of the leading home appliances’ manufacturers in Europe. It provides high quality domestic products that are eco-friendly, luxurious, energy-efficient and durable. The company sells its products in more than 70 countries worldwide.

The company offers these types of electric boilers:

o   Small capacity electric boilers – these water heaters are made of high-quality anti-corrosion enamel and have volumes of 5-15 litres. The temperature in the boiler can reach 75 °C.

o   Wall-mounted vertical electric boilers – these water heaters have volumes of 30-200 litres and are suitable for small premises (have smaller external diameter). The boilers are manufactured from enamelled high-quality steel sheet and have additional protection against corrosion. The temperature in the boiler can reach 75 °C.

o   Wall-mounted horizontal electric boilers – these water heaters have volumes of 50-200 litres. The boilers are very durable, have protection against freezing. The temperature in the boiler can reach 75 °C.

KOSPEL S.A. – Polish company that was established in 1990. It is a manufacturer of electric water heaters. The products of the company are certified, modern, energy-saving, convenient.

The company offers these types of electric boilers:

o   Electric central heating flow boilers – these water heaters are designed for wet central heating installations or hot water cylinders. They are perfect for seasonal living places (summer houses) or places with limited ability to build a chimney.

o   Electric underfloor heating boilers – these water heaters are designed for wet underfloor heating installations.

o   Electric central heating boilers with an outdoor temperature control – these water heaters are designed for central heating installations or hot water cylinders. The boiler’s system quickly reacts to the changes of temperature and ensures maximum efficiency of energy consumption.

Tonon Forty spa – Italian manufacturer in the heating and air-conditioning market. The company was founded in 1963. The production of the company can be characterized as high-quality, innovative, meeting the requirements of consumers.

The company offers these types of electric boilers (Forty tanks products line):

o   Stainless steel vertical tank boilers – these water heaters are made of stainless steel, have high corrosion resistance. The boilers have capacity from 200 to 1450 litres and are used for domestic hot water needs. The temperature in the boiler can reach 90 °C.

o   Stainless steel modular boilers (short and long models) – these water heaters can provide large amounts of hot water and are used in large buildings, hospitals, hotels. The temperature in the boiler can reach 90 °C.

GEMINOX CHAUDIERES – French manufacturer of various boilers (electric boilers too), hot water cylinders. The company offers quality and efficient heating products.

The company offers these types of electric boilers:

o   Wall-mounted electric boilers.

ACV Group – Belgian manufacturer that has been manufacturing boilers, radiators and condensers since 1922. The company provides innovative heating and water products in more than 40 countries.

The company offers these types of electric boilers:

o   Wall-mounted electric boilers – these boilers are used for heating and can generate hot water on demand. They have electronic sequencing control and external temperature control. The capacity of these boilers ranges from 10 to 40 litres.

o   Commercial electric boilers – these water heaters are compact floor standing, elegant (red-coloured or white-coloured). The volume of these boilers ranges from 60 to 380 litres.

Applied Energy Products Ltd (Redring) – British manufacturer of innovative and environmentally friendly water heating equipment.

The company offers these types of electric boilers:

o   Wall-mounted unvented electric boilers – these water heaters have compact shape and can be mounted under sink. It is energy saving and minimizing heat loss. The temperature in the boiler can reach 95 °C.

o   Wall-mounted vented electric boilers – these water heaters are compact, economical. The temperature in the boiler can reach 75 °C.

Acme Engineering Products, Inc. – CanadianAmerican manufacturer that produces air conditioning, ventilation and heating systems. The company is known for its top quality, design-built products. The latter are exported to Africa, Japan, China.

The company offers these types of electric boilers:

o   Commercial electric steam boilers – these water heaters are high voltage, floor standing, very efficient and have no thermal loss (almost 100% of electrical energy is transformed into heat).

o   Electric steam boilers – these water heaters are compact, easily installed, very economical and have no heat loss (almost 100% of electrical energy is transformed into heat).

Water circulation in a boiler

The boiler operates effectively only when the tubes of its heating surfaces are intensively cooled by water, steam or their mixture. So a coolant must circulate at a certain velocity in the pipes. In economizers or air heaters water and steam moving is forced due to a pump or the difference of the steam pressure in the drum and superheater. In the evaporating surfaces of the boiler water circulation can be natural and forced.

The simplest scheme of the natural water circulation in the closed circuit of the boiler consists of these elements: drum, lower header of tubes and connecting them two rows of pipes. Circuit is filled up with water. Its altitude is a half of the drum. Tubes are intensively heated, pipes are outside the boiler masonry and are not warmed. The bubbles of the steam formed in the heated tube mix with the water and rise up into the boiler drum. Here separated steam flows out of the drum and additional water is supplied instead. Water comes down by unheated tubes; these pipes are called downcomers, heated ones-upcomers or evaporation ones.

In the unheated pipes water density is larger than density of the water and steam mixture in heated ones. Driving force of the circulation (Pa) takes place due to density difference in the connected pipes.

Steam boilers of natural circulation

The most popular are steam industrial boilers DKVR (reconstructed two drums boiler of vertical water pipes) made in Russia. The output of these boilers is 1,04, 1,67, 2,71 and 4,17 kg/s, steam pressure – 1,4 MPa. In most cases saturated steam is produced in these boilers, but, if it is necessary, a part of the water pipes can be taken out and instead of them a steam superheater is installed. Boilers are heated by gas or mazut.

The same construction scheme is characteristic to all DKVR boilers: they are two drums boilers of natural circulation with a shielded furnace. Boiling pipes layed out in a corridor order are fixed to the drums installed along. Shield pipes of furnace and boiling ones are joined to the long upper drum. Diameters of the pipes and drums, the distances between their centers are the same, so it is easier to produce them. Side walls of the furnace are entirely shielded. Front and rear shields are installed in the boiler DKVR. Ceiling of the furnace chamber consists of the bent ends welded to the upper drum of upper shield pipes. Lower ends of the shield pipes are fixed to two headers installed along side walls of the boiler. In order to form circulation circuit a front part of the header is fixed to the upper drum by unheated downcomer pipe. Other part of the header is joined to the lower one by unheated short pipes. The bottom of the boiler leans on the steel frame, so warmed it can get longer upwards. The furnace is installed under the projected out part of the upper drum. In front wall of this boiler burner for gas and mazut is installed.

Combustion products get into the final combustion chamber through orifice of the furnace rear wall where gas burns down. Smoke gets into the bank f convectional boiling pipes taking the roundabout way of the brick partition. It makes two runs due to a cast-iron partition. Flue gas leaves through a rear wall orifice of the boiler. Water circulates in the pipes because the pipes installed nearby furnace are heated more intensively than those at the end of the boiler heated by taking off smoke.

If it is necessary to overheat steam, superheater is installed at the beginning of the boiling pipes bank.

Settlings from the external surface of the boiling pipes bank are removed by the steam blown through stationary blasting equipment or by compressed air supplied through the openings of the side walls.

Boilers DKVR entirely or partly assembled are transported by railway to the mounting place.

Boilers KE (Russia) with stoker – fired furnace are produced to burn solid fuel. Their construction differs a little from DKVR ones, output – from 0,7 to 7 kg/s. Boilers DE (Russia) predestinated to burn gas and mazut are manufactured of the same output range. Water heaters-economizers and air heaters are installed in the exterior of the boiler as separate blocks.

In the industrial boilers large convectional evaporating equipment is installed which is not used in modern power ones. In such boilers water boils and vapours getting heat from burning torch by radiation in the shield pipes of the furnace. Such power boiler consists of all the elements characteristic to the modern water pipes boiler: shield pipes, superheater, air and water heaters and so on. A boiler consists of one drum, it is heated by different sorts of coal dust or crumby peat. Heating by peat in front of the boiler two bruising mills are installed. All walls of the furnace are shielded by pipes. In the funnel shaped bottom part of the furnace slag gets colder and falls out into the slag chamber. In the upper part pipes of the rare shield make up a bank of four rarefied rows of pipes-festoon, behind it a convectional steam superheater of two grades is installed. In the upper part of the boiler emergency exploiding valves are arranged necessary according to the rules of the boiler operation burning gas, mazut and fuel dust. In the convectional shaft economizer and air heater of two grades are installed.