How to choose an electric boiler for heating a private home

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Published: 06/08/2019

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A growing number of social green movements around the world are demanding that governments pay due attention to environmental issues in their life support systems. In response to their demands, as an alternative to stove heating, models of economical electric boilers for heating a private home were released onto the market.

• 1 How relevant is the method of heating with an electric boiler?
• 2 Advantages of electric boilers
• 3 How to choose a good electric boiler 3.1 Power
• 3.2 Energy efficiency

The most economical electric boiler is a myth

Electricity is much easier to convert into heat than other energy sources - natural gas, solid fuel, diesel fuel. Here are 3 simple examples of heat by-products when using electricity:

• the windings of any operating electric motor always heat up;
• a light bulb (even an LED one) produces heat along with the light;
• Even the wires through which current flows become heated.

Please note that the equipment listed is designed to perform its functions, and not to heat the house. The motor rotates something, the lamp shines, the wiring supplies them with energy. The formation of excess heat is a side effect that occurs due to the resistance of these elements.

Spiral and induction heater converting electricity into heat with 99% efficiency

To convert all electrical energy into thermal energy, it is enough to create a high resistance section in the circuit, which itself will not collapse from heating. This element is called an electric heater. The second (more complex) way to obtain heat is to create Foucault induction eddy currents that heat a metal object in the area of ​​action of the inductor coil.

Important point. Regardless of the conversion method, 98–99% of electricity will turn into heat. That is, any electric heating device operates with an efficiency of 98–99%, no less. This means that the most economical electric boiler does not exist; all units are equally efficient. No matter what home appliance sellers claim.

Criterias of choice

Before purchasing such equipment, it is recommended that you familiarize yourself with the main characteristics of the units:

• unit power (standardly, the required indicator is calculated using the formula 1 kW per 10 m², however, it is additionally necessary to take into account possible heat loss, the number of windows and doors, wall material and other factors, including the climatic features of the region);
• single- or double-circuit device (depending on whether the owners require hot water supply or already have it);
• storage capacity volume;
• wall or floor boiler;
• equipped with functions (for example, overheating protection, power-on indication);
• equipment (is there a remote control, circulation pump, etc.).

When choosing, you need to take into account many factors, since replacing a device is problematic and involves unexpected costs. For example, a 40 kW electric boiler heats an area of ​​about 400 sq.m., but if in doubt, it is better to consult an expert.

Selection of heat generator by power

To select the power of an electric boiler, first of all, calculate the heat losses of your home. You probably know the approximate method of calculation: to heat 100 square meters of building area, a heating unit with a capacity of 10 kW is taken, for 200 m² - 20 kW, and so on. If you want to get a more reasonable result, use our calculation methods.

A very approximate calculation method - we divide the area of ​​​​all rooms by 10, we get heat loss in kilowatts

Now let’s define the tasks that an electric boiler must solve (select the desired list item):

• round-the-clock heating of an apartment, cottage, country house;
• the same, with water heating for domestic needs;
• work at night at a cheap rate;
• standby heating – maintaining the air temperature +5…10 °C.

Note. Night heating of the house with an electric boiler can be combined with heating of the heat accumulator. At 7.00 the unit turns off, then the water system receives the heat accumulated in the buffer tank. 2 conditions: the allocated limit for electricity consumption must be 15...20 kW + powerful electric boiler.

Full heating with electricity is not cheap and is used as needed. A more profitable option is night heating from 23.00 pm to 7.00 am, when the cost of energy is half as much. The standby mode is used on objects under construction or dachas, where the owners spend 2-3 days weekly.

We select the power of the electric heating boiler depending on the tasks:

1. For round-the-clock operation, the unit is selected with a margin of 10...20%. That is, the heat loss figure is multiplied by a factor of 1.1–1.2. For example, a house with an area of ​​60 square meters loses 4 kW, the productivity of the electric boiler will be 4 x 1.2 = 4.8 kW.
2. For hot water supply (DHW), the power of the unit should be increased by 50%. That is, multiply the figure 4 kW from the example by a factor of 1.5 (we get 6 kW).

   
   To obtain hot water, it is customary to connect a single-circuit electric boiler to an indirect heating boiler through a three-way valve. The latter switches the coolant between the tank and the heating system

3. An electric heating device for night heating can be taken without a power reserve if it is replaced in the morning by a gas or solid fuel boiler. Reducing the temperature to 18–19 °C during sleep will not cause much discomfort, but will save money.
4. The power of the electric boiler that maintains positive temperatures in the building is taken with a reduction factor of 0.6–0.7 (minus 30–40%) of the amount of heat loss.

Advice. To organize DHW, you do not need to look for a double-circuit boiler. Usually there are 2 options: installing a separate electric water heater or a powerful heat generator plus an indirect heating boiler.

The performance of the heater for nightly “charging” of the heat accumulator depends on the volume of the tank and is calculated individually. The selection of an electric boiler under standard conditions is described in the video:

Advantages and disadvantages

Electric boilers have the following advantages:

• simple installation and simple operation - just read the instructions;
• the ability to choose a unit to suit almost any style in the interior of a private home;
• in the case of wall-mounted models, space in the room is saved;
• the devices do not make noise;
• there is no need to install a chimney, since there are no harmful combustion products;
• the devices are considered safe from an environmental point of view;
• regulation of the required temperature.

But there are also disadvantages. The negative aspects of using boilers include dependence on electricity.

With the latter, there are often interruptions in suburban areas, which affects heating (the devices do not function at such moments). Additionally, the costs of electricity consumption are taken into account.

Complete set of heating units

We have already listed the elements of any electric boiler in the basic, cheapest configuration. This is a heating unit, thermostat, automation with an actuator, controls and a temperature sensor.

An important nuance. In budget versions of boilers, the executive element is a magnetic starter. It clicks loudly when the heating is turned on, the sound is clearly audible in the rooms adjacent to the boiler room.

In an extended configuration, manufacturers supply electric boilers with the following equipment:

• low-noise modular contactor instead of a magnetic starter;
• circulation pump;
• membrane expansion tank for a closed heating system;
• overheating and coolant pressure sensors;
• safety group – automatic air vent, safety valve;
• circulation sensor – for induction heat generators;
• weather automatics;
• LCD display, programmer, GSM remote control module from a smartphone.

Naturally, the “fat” equipment of an electric boiler will cost much more than the “poor” one. On the other hand, you will still have to buy an expansion tank, a pump and a safety group. It is much more convenient to install the unit when these elements are hidden inside the housing.

Features of operation

There are no special requirements when servicing boilers. It is enough to monitor the fluid level in the system, replenishing it if necessary (with water or antifreeze). In addition, the pressure in the system is monitored thanks to the built-in thermometer.

However, given that the devices are equipped with modern automation, the units operate automatically, with virtually no human intervention.

If sounds that are not characteristic of the equipment are observed, crackling sounds are heard from the device, or an unpleasant odor appears, it is recommended to contact a specialist after first turning off the power to the device.

Which electric boiler to choose - recommendations

In 90% of cases, we recommend choosing an electric boiler with heating elements. These are reliable devices that are equally suitable for different heating systems - radiators, heated floors, floor or baseboard convectors. Select the level of staffing based on the conditions of installation, operation and the allocated budget.

A few more tips:

1. For your apartment, definitely take a wall-mounted electric mini-boiler room, equipped with heating elements, its own pump and tank.
2. If the electric boiler must work in tandem with a solid fuel or gas unit, it is better to choose a model without a built-in pump and expansion tank. The specified equipment is connected separately - the tank works for the entire system, the pump is controlled by a room thermostat, as shown in the diagram.

   
   It is more convenient to operate the circulation pump when it is located separately from the boiler

3. Install a remote thermostat. Then the boiler will focus on the temperature of the air, and not the coolant.
4. Choose an electrode heat generator in 3 cases: limited budget, too little space in the boiler room, or connection to a gravity heating circuit without a pump.
5. Electrode units create the least problems in open systems - the resulting gases safely escape through the atmospheric expansion tank.
6. Choose an induction boiler according to your desire and availability of funds. But keep in mind: operating experience has shown that the specified device is no better than a heating element. No special technical problems were noted with induction heaters, only financial ones.

Comment. An electrode-type boiler for a gravity system must have pipes of the appropriate diameter (minimum Ø32 mm), the supply pipe is directed upward.

For a water heated floor, only an electric heating element boiler is suitable. It is difficult for induction and electrode units without stepwise heating to maintain a low water temperature in floor circuits - 35...45 °C.

Main types of heaters

The operation of the boiler depends on the type of equipment. Companies supply electric units with 3 types of heating elements.

According to this criterion, the following devices are distinguished:

1. Equipped with heating elements (such elements are located in a quartz filling and a shell - a special housing). Current passes through the tungsten wire and heats it up. The heat that is released increases the temperature of the water circulating inside the tank. The latter enters the heating system - into pipes and radiators, or is used for hot water supply.
2. Equipped with electrodes. The cylindrical steel body has a connected “zero” wire. Inside the structure there is the electrode itself with a connected “phase”. With the help of a circulation pump, undistilled liquid begins to move in the system. Since water in this design is characterized by electrical resistance, as soon as current passes through the liquid, the temperature of the latter increases.
3. Equipped with an induction coil with a metal core located inside. Additionally, the element is wrapped with wire. When electricity passes through the coil, vortexes arise, heating the part. Since it is in a liquid, the temperature of the water rises.

Finally, about energy consumption

The natural desire of a homeowner is to know how much electricity an electric boiler will consume when heating a private home. Unfortunately, actual consumption cannot be predicted. The indicator is too individual and depends on a number of factors - the degree of insulation, the temperature maintained inside, the weather.

Monthly consumption can be calculated approximately: take 50% of the estimated heat loss of the house, multiply by 24 hours and 30 days. Example: losses are 6 kW, half - 3 kW, per day 3 x 24 = 72 kW, per month - 72 x 30 = 2160 kW. Why we take ½ power: during the season the weather is not always cold, the warmer it is outside, the more often the electric boiler turns off.

An example from personal experience. A house of 100 m² is heated at night with a 9 kW electrode boiler for 8 hours, the region is southern. Over 6 months of the heating season, the electric boiler consumed 9104 kW. Average monthly energy consumption is 1517 kW, average daily energy consumption is 1517 / 30 = 50.6 kW.

Rating of TOP 7 best models

Video description

In the video, a specialist talks about the Protherm Panther KTV wall-mounted boiler:

Floor standing gas boilers

They are presented on the market from the same manufacturers, so the range is wide. And yet we have to choose the best floor-standing double-circuit gas boiler.

Vaillant atmoVIT VK INT

First place again goes to German equipment. There are several types in the model range of this unit, differing from each other in power. This figure varies in the range of 16-56 kW. Basically, a boiler is required to heat hot water, but one model has an instantaneous heater installed inside.

Boiler features:

• atmospheric injection burner without fan;
• cast iron heat exchanger;
• Efficiency 92%;
• flame, temperature and draft control sensors.

Boiler Vaillant atmoVIT VK INT Source mostszh.ru

Viessmann Vitogas 100-F 29-60

This brand is one of the most extensive in terms of model range. It contains 15 models with a power from 29 to 60 kW, which is very convenient if you need to select the required unit. Experts say that if the consumer is faced with the task of choosing an economical gas boiler, then this is it.

Moreover, all models easily cope with gas pressure differences in the main pipeline. That is, it is not a problem for them.

Design features:

• the burner is made of stainless steel, it is rod type;
• heat exchanger made of gray cast iron;
• full automation of equipment;
• gas control relay.

Viessmann Vitogas floor standing boilers Source static.wixstatic.com

Prices: summary table

Gas boilersBoilersWays to save Solid fuel boilers

conclusions

Electric boilers are considered a good alternative to gas and solid fuel units. The equipment is used as the main or additional source of space heating, and can also provide hot water supply.

When choosing, take into account the characteristics, functions and power of the device in order to purchase the most suitable model. For example, a 1 kW electric boiler can heat 10-12 m².

You may be interested in knowing what an electric boiler is.

Which manufacturer is better?

There are many brands on the Russian market that supply electric boilers of various capacities and pricing policies.

Among the manufacturers it is worth highlighting:

• EVAN is a domestic company operating since 1997. It has an expanded range of heating equipment control units, develops its own network of representative offices and warranty workshops, which allows for timely maintenance of devices.
• Protherm is a Slovak brand whose products meet modern European standards for energy efficiency and safety. It is distinguished by careful control of assembly and quality of component materials.
• Stout is a Russian company whose products combine the best price and European quality. The brand's factories are located not only in Russia, but also abroad. The quality of the models supplied to the market is ensured by high-quality heating elements, safety valves and electronics.