Efficiency of a gas boiler - what it depends on and how to increase it

What is efficiency

Nowadays, many companies, both domestic and foreign, produce gas boilers. When choosing such equipment, owners of private houses in Russia, unfortunately, mainly look only at its price and power. Meanwhile, a very important parameter that allows you to choose a good heating unit is efficiency. A gas boiler, among other things, must be highly efficient.

The higher the efficiency of such equipment, the less home owners will subsequently need to pay for blue fuel. The efficiency of gas boilers is called the ratio of fuel consumed to thermal output.

Types of heat loss

There are nominal and real efficiency. The real one is always less than the nominal one. This is also due to the fact that there are different types of heat loss. The following types of heat loss are distinguished:

Physical underburning. The indicator depends on how much excess air, which does not take part in the formation of thermal energy, is present in the equipment during fuel combustion. Its value is also influenced by the temperature of the exhaust gases. In winter, during severe frosts, when the boiler is operating at full capacity, physical underburning can reach 20%.
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Heat loss from gas heating and low efficiency
Chemical underburning. The value of this criterion increases depending on the amount of carbon monoxide. Carbon does not burn in heating equipment and exits through the chimney, however, it has the ability to produce large amounts of thermal energy. Carbon monoxide is formed due to the combustion of carbon. Heat loss from chemical underburning ranges from 5-7%.
Mechanical underburning is typical for solid fuel heating boilers. This is a loss of efficiency as a result of incomplete combustion of fuel and the formation of ash. The percentage is insignificant - only 1-3.

In addition, heat loss can occur through the walls of heating devices. In this case, the heat is dissipated directly into the environment through the outer lining of the heating device.

Formula for calculating average efficiency

The efficiency is also indicated in the technical data sheet of the boiler. However, in this case, the consumer is provided with only an average indicator, which is calculated by companies involved in the manufacture of such equipment using the following formula: n=(Q/Qo)*100%.

Here Q is the heat that was released, accumulated and used to heat rooms; Qo is the total amount of thermal energy released when fuel is burned.

Unfortunately, using this formula, you can only get ahead of the average efficiency. Gas boilers with high performance indicators are presented in a fairly large assortment on the modern market. For some modern brands of such units, the efficiency can reach 98%. This is, of course, a lot. However, in practice, modern gas units, unfortunately, often do not demonstrate such efficient operation. During the operation of such equipment in private homes, various types of heat loss occur, which has the most negative impact on efficiency. That is, when installed in a house, gas boilers usually lose performance.

Top 5 condensing gas boilers by rating

The preferred gas condensing boiler unit is one that meets the urgent needs of the home owner in terms of thermal energy production, is equipped with modern automation for economical and safe operation, and has an affordable price.

It is important to note that condensing boilers do not have the concept of “low price”; they initially have a high cost due to the use of high-strength materials.

BAXI LUNA Platinum+ 1.32

This is a gas condensing floor-standing boiler from a well-known Italian manufacturer. The boiler unit is single-circuit, designed exclusively for heating.

Advantages of modification:

Ultra-high efficiency - 105.7%.
Heating area up to 350 m2.
Heating capacity – 35 kW.
Low specific fuel consumption, maximum gas consumption is not higher than 3.49 m3/hour.
Fuel versatility, works with any type of gas - mainline/liquefied.
Full-featured protection.
Pre-cleaning of condensate.
Pre-cleaning of feed water - built-in filter.
Price: 83420 rub.

Disadvantages of the Baxi floor-standing condensing boiler:

works only with low-temperature coolants in the “warm floor” system;
high price;
Sold only to order, long delivery period.

Buderus Logamax plus GB062-24 KD

Also a condensing boiler from a German company. A model with a heating output of 24 kW designed for heating residential buildings.

Advantages of modifying Buderus condensing boilers:

Ultra-high efficiency – 103.0%.
Heating area up to 250 m2.
Heating capacity – 24 kW.
Low specific fuel consumption, maximum gas consumption is not higher than 3.18 m3/hour.
High-quality construction materials, durability of the boiler.
High level of automation and control of the performance of installation components.
Price: 63,700 rub.

The disadvantages of the boiler unit are the high cost of the boiler and repair work.

Bosch Condens 2500W WBC 24-1

Turkish double-circuit gas boiler with heating capacity - 24 kW.

Advantages of modification:

Ultra-high efficiency – 110.0%.
Heating area up to 192 m2.
Heating capacity – 24 kW.
Low specific fuel consumption, maximum gas consumption is not higher than 3.18 m3/hour.
High-quality construction materials, long service life of the boiler.
High level of automation and control of thermal processes.
Expansion tank – 6 l.
Price: 89670 rub.

Disadvantages of a Bosch condensing boiler:

inaccessibility to work on liquefied gas;
high cost of the boiler and repair work.

Vaillant ecoTEC plus VU INT IV 246/5-5

The German brand Vaillant, a leader in the production of household heating boilers, produces a single-circuit condensing model ecoTEC plus VU INT IV 246/5-5 with a steel heat exchanger. The boiler is designed for heating residential and public premises up to 200 sq.m.

Advantages of the Vaillant boiler:

Ultra-high efficiency - 108.0%.
Heating area up to 200 m2.
Heating capacity – 20 kW.
Low specific fuel consumption, maximum gas consumption is not higher than 2.6 m3/hour.
High-quality construction materials, durability of the boiler.
Remote control.
High level of automation and performance monitoring of installation components
Expansion tank – 10 l.
Price: 62270 rub.

The disadvantages of the boiler unit are the high cost of the boiler and repair work.

Viessmann Vitodens 100-W B1HC043

Another German single-circuit condensing boiler unit. Powerful model - develops up to 35 kW and is capable of heating 350 sq.m.

Viessmann Vitodens boiler. Photo source: ferencziepuletgepeszet.hu

Advantages of the Viessmann boiler:

Ultra-high efficiency - 108.7%.
Heating area up to 350 m2.
Thermal heating capacity is 35 kW.
Low specific fuel consumption, maximum gas consumption is not higher than 3.46 m3/hour.
High-quality construction materials, durability of the boiler.
Remote control.
High level of automation and control of combustion processes.
Price: 105806 rub.

The disadvantages of the boiler unit are the high cost of the boiler and repair work.

Actual efficiency - formula

On site, the efficiency of such equipment is usually determined using the following formula: η = 100 - (q2 + q3 + q4 + q5 + q6).

Here:

q2 - heat losses due to heated combustion products going into the pipe;
q3 — losses due to incorrectly chosen proportions of the gas mixture (underburning);
q4 - losses due to soot inside the boiler and mechanical underburning;
q5 - losses due to fluctuations in outside air temperature.

It is believed that the boiler efficiency is most strongly influenced by the q2 indicator. That is, to the greatest extent, the performance and efficiency of a gas heating unit depends on how much heat it induced literally “flies down the drain.”

How to calculate power

Before purchasing heating equipment for servicing a private home, it is necessary to calculate the power that would be enough to maintain high-quality operation of the boiler. If you do not have sufficient experience and knowledge, seek help from professionals, as mistakes at this stage will certainly affect the performance and durability of the equipment.

Note!
Problems arise not only in case of insufficient power of heating equipment, but also in case of its excess. There are special formulas for calculating power. Using them, you can independently calculate which boiler is suitable for servicing your home.

When calculating the power of a gas boiler, the following parameters should be taken into account:

average temperature in the winter months in a given area;
Gas boiler operation and heat loss
what materials the house is built from;
what materials were used to insulate the house, and whether they were used at all;
living area of the house.

You can use special formulas to calculate the power of heating equipment for a private home.

Note!
The power of a gas boiler also depends on whether hot water is required in the house.

Which boilers have greater efficiency

Domestic manufacturers currently produce quite powerful and reliable gas heating equipment. However, in our country, unfortunately, too much attention is still not paid to saving resources. Therefore, today imported gas boilers have the highest efficiency. This is especially true for low-temperature condensing models, in which the heating rate of the coolant does not exceed 70 °C, and the exhaust gases - 110 °C.

The most productive brands of gas boilers, the efficiency of which is very high, on the modern market are:

"Buderus."
"Wissman."
"Baksi."
"Vailant."

De Dietrich is also considered a very good brand of heating units with high efficiency.

How to increase the efficiency of a gas boiler: basic methods

If the boiler in the house does not work with proper performance, its owners will have to overpay for gas consumption, which, of course, will have a very negative impact on the family budget. To increase the performance of the heating unit and thereby avoid unnecessary expenses, you can:

modify the chimney or improve the conditions for exhaust gas removal;
clean the combustion chamber;
clean or replace the lines of the home heating system;
make changes to the boiler design;
adjust the proportions of the gas mixture in the combustion chamber using a damper.

Using such techniques, it is possible to increase the efficiency of both a double-circuit gas boiler and a single-circuit one. Such methods are also suitable for wall-mounted or floor-mounted gas heating units.

How to adjust the power of a gas boiler?

You can adjust the power of the unit in two ways:

Reduce burner performance to a level at which the automation can find the optimal operating mode.
Increase the power of the heating system by adding radiators or replacing them with more powerful ones.

In some cases, it is advisable to use two methods at once. Of course, the second option is more expensive, but you often have to choose it. It is especially relevant if the heat produced by the installed system is not enough.

Note! When replacing heating, you should take into account the volume of the expansion tank of the gas boiler model. For example, the tank of the Gepard unit provides a coolant volume of 50 l

If the amount of water increases when installing new radiators, you will need to connect an external expansion tank.

The productivity of the burner device can be reduced by reducing the fuel supply to the burner. This requires changing the gas valve settings. The burner power settings for this element are adjusted by rotating the adjusting screws located on the valve body.

You can also reduce the power of the device using settings by changing them in the service menu. For ordinary users, Protherm boilers have a general menu, which is described in the instructions. However, there is also a hidden service menu, which is intended for specialists. It becomes available only when you enter the code. Therefore, only a service center technician can use it.

In the service menu, the following parameters are reconfigured:

power in the range from 9 to 23 kW;
run-time of the circulation pump in heating mode is between 2 and 60 minutes;
time delay after operation in heating mode for anti-cycling - protects against frequent switching on and off (does not work in DHW mode);
coolant temperature – from 20 to 80ºC.

For a heating system with a power of 4 kW, set:

power – 9 kW;
coolant temperature – 60-70ºC;
anticycling time – 15-20 minutes.

These are approximate settings, but you need to ensure that the burner ignites no more than every 15 minutes. To do this, select the optimal coolant temperature.

However, not all brands of gas boilers have the ability to adjust the anti-cycling time. In this case, you will have to limit yourself to adjusting the power of the unit. On some boilers, you can manually set the pump operating mode using a switch located on it. To reduce the clock frequency, it is necessary to increase the pump speed.

Thus, in different ways, a power balance is achieved between the heating system and the gas boiler.

What to do with the chimney

The performance of boilers is greatly influenced by the condition of the combustion products discharge pipe. If the chimney becomes clogged with soot, this will reduce its diameter and, accordingly, draft. Experts recommend checking the condition of the pipe that discharges gas combustion products at least once a year.

To increase efficiency, it is best to connect a closed-type boiler to a coaxial chimney. In this case, the air will begin to enter the combustion chamber through the outer cavity of the two-cavity pipe, already slightly heated. This, in turn, will reduce the initial heat costs by several percent.

Adjusting the proportions of the gas mixture

In the design of any modern heating unit, among other things, there is such an element as a damper. By correctly adjusting its position, you can significantly increase the efficiency of a gas boiler.

If the boiler damper is opened too much, too much air will enter the combustion chamber. In this case, a draft will form in the firebox, drawing some of the blue fuel out into the street along with the combustion products.

An even more serious decrease in the efficiency of a gas boiler can be caused by closing the damper too much. In this case, little air will enter the combustion chamber. As a result, some of the gas simply will not burn and will also exit into the chimney along with the smoke. The efficiency of the heating unit with this position of the damper can decrease by as much as 7%.

It will not be difficult to adjust the proportions of the combustible mixture inside the boiler firebox yourself. This can be done experimentally. The home owner simply needs to pull out and close the damper until the boiler thermometer shows the highest heating of the coolant in the heating system.

Operating rules for boiler devices, compliance with which affects the efficiency value

Any type of heating unit has its own optimal load parameters, which should be as useful as possible from a technological and economic point of view. The operation process of solid fuel boilers is designed in such a way that most of the time the equipment operates in optimal mode. This operation can be ensured by following the rules of operation of heating equipment operating on solid fuel. In this case, you must adhere to and follow the following points:

it is necessary to observe acceptable modes of blowing and exhaust operation;
constant control over the intensity of combustion and completeness of fuel combustion;
control the amount of entrainment and failure;
assessment of the condition of surfaces heated during fuel combustion;
regular boiler cleaning.

The listed points are the necessary minimum that must be adhered to during the operation of boiler equipment during the heating season. Compliance with simple and understandable rules will allow you to obtain the efficiency of an autonomous boiler stated in the characteristics and improve the operation of a solid fuel boiler.

We can say that every little thing, every element of the design of a heating device affects the value of the efficiency factor. A properly designed chimney and ventilation system ensure optimal air flow into the combustion chamber, which significantly affects the quality of combustion of the fuel product.

Ventilation performance is assessed by the excess air coefficient. An excessive increase in the volume of incoming air leads to excessive fuel consumption. Heat leaves more intensely through the pipe along with combustion products. When the coefficient decreases, the operation of boilers deteriorates significantly, and there is a high probability of oxygen-limited zones appearing in the furnace. In this situation, soot begins to form and accumulate in large quantities in the firebox.

The intensity and quality of combustion in solid fuel boilers require constant monitoring. The combustion chamber must be loaded evenly, avoiding focal fires.

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During combustion, it is important to prevent failure of the fuel resource, otherwise you will have to face significant mechanical losses (underburning) of fuel. If you do not control the position of the fuel in the firebox, large fragments of coal or firewood falling into the ash box can lead to unauthorized combustion of the remaining fuel mass products.

Soot and resin accumulated on the surface of the heat exchanger reduce the degree of heating of the heat exchanger. As a result of all of the above violations of operating conditions, the useful volume of thermal energy required for the normal operation of the heating system decreases. As a result, we can talk about a sharp decrease in the efficiency of heating boilers.

Cleaning the combustion chamber

Blue fuel is distinguished primarily by the fact that its combustion does not produce too much soot. Of course, it is necessary to clean the furnace of a gas-fired boiler less often than of solid fuel equipment of this type. But it is still necessary to wash the combustion chamber of such heating units from time to time. Experts believe that owners of gas boilers need to do such cleanings at least once every 3 years.

Scale in pipes

In order not to spend a lot of money on gas, it is imperative that owners of private houses also monitor the condition of the heating system lines. The boiler's performance can also be reduced by regular clogged pipes. Experienced owners of country houses, for example, do not advise changing the coolant in the heating system circuit too often. It is not advisable to drain water from the mains even after the end of the cold season. The fact is that any water from a well, a well or a centralized system contains a huge amount of dissolved minerals, which subsequently fall out in the pipes in the form of sediment.

What changes can be made to the design?

To increase the efficiency of wall-mounted or floor-mounted gas boilers, special turbulators can be installed between the combustion chamber of the unit and its heat exchanger. This is the name for special plates that can significantly increase the area of heat energy extraction.

The operation of the boiler can also be controlled using temperature sensors. Such devices are installed in the premises of the house and turn on/off the burner of the heating unit depending on the air warming up to the temperature set by the owners. When using sensors, it is important to correctly configure and synchronize the operation of the boiler in accordance with the latter’s readings.

The burner of gas heating units is turned on when the air temperature in the premises drops below the specified parameters using a special “lighter”. This is the name given to a small burner whose gas never goes out. Such a “lighter” cannot burn a lot of blue fuel. However, during the season, due to its operation, several cubic meters of blue fuel are often burned. To reduce losses, the usual “lighter” in the boiler can be replaced with a “piezo”. Such a device will work no worse than a traditional one, and the savings from its use are quite significant.

Other changes

Among other things, gas heating units equipped with modulating burners also have very good performance indicators. Modern boilers from the best European manufacturers are initially supplemented with similar two-level or fully modulated elements. Burners of this type are able to independently adapt to the actual operating parameters of the heating system installed in the house. Thus, the percentage of underburning in boilers of this design is reduced to a minimum.

In conventional heating units, home owners can, among other things, try changing the position of the burner. Installing this element closer to the water circuit allows you to increase the efficiency of the boiler by several percent. In this case, the heat balance of the unit increases significantly.

Condensing boilers

Thus, increasing the efficiency of a gas boiler will be relatively easy. But of course, it is better for owners of country houses to immediately purchase economical and productive equipment of this type. Condensing gas boilers, as already mentioned, have the highest efficiency.

Such equipment appeared on the domestic market relatively recently. The efficiency of these boilers is determined primarily by the fact that they additionally use the energy generated due to the condensation of water vapor from the exhaust gases. The efficiency of such equipment is an order of magnitude higher than that of conventional heating units.

Many manufacturers of such boilers even claim that they produce gas boilers with an efficiency of 100% or higher - 108-109%. Of course, such statements are disputed by experts. After all, as you know, the efficiency of any equipment rarely reaches 100%. Such an indicator cannot exceed this figure at all. Of course, even the most advanced heating unit is not capable of increasing the amount of heat when burning the same volume of blue fuel.

But still, the efficiency of gas condensing heating boilers is much higher than conventional ones. According to experts, it can reach 98-99%.

In terms of gas consumption efficiency, condensing boilers are thus significantly superior to simple ones. However, unfortunately, such equipment also costs much more than traditional equipment. Whether or not to purchase such a unit is a matter of choice for the owners of the gasified house themselves. Most likely, during the operation of a gas boiler with a high efficiency condensing boiler, the difference in cost will eventually pay off. But this will not happen too quickly, for which buyers should be prepared in advance.

Ways to increase efficiency

In order for the heating system to operate with minimal heat loss, you should familiarize yourself with effective ways to improve the efficiency of a gas boiler. To do this, it is necessary to eliminate as much as possible all types of heat loss.

To reduce the percentage of physical underburning, you should monitor the condition and cleanliness of the flame tubes and water circuit. Soot forms on the pipeline, and scale forms on the circuit, so these elements of the heating system require regular cleaning.
There should be no excess air in a gas boiler, since heat that could be used to heat the coolant also goes into the chimney with it. This problem can be solved by installing a draft limiter on the chimney pipe.

How gases circulate in the boiler
Adjusting the blower damper. This can be done using a thermometer installed in the boiler. You just need to put the damper in such a position that the maximum coolant temperature is achieved.
Make sure that normal traction is maintained. It decreases as a result of the narrowing of the chimney cross-section. This can be avoided if you regularly clean the outlet pipe, because soot sticks to its walls.
It is necessary to regularly clean the combustion chamber, as soot forms on the surface of its walls, which increases fuel consumption.

Installation of a coaxial chimney

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If you are looking for options on how to increase the efficiency of a gas boiler, pay attention to what kind of chimney is installed. Traditional outlet pipes have a number of disadvantages, the main one of which is their dependence on weather conditions. An alternative to a conventional chimney can be a coaxial chimney, which has the following advantages:

significantly increases the efficiency of a gas boiler;
resistant to high temperatures;
can be made in different versions;
allows you to save fuel;
ensures long-term maintenance of room temperature.

Coaxial chimney

The installation of a coaxial chimney does not require much effort. The design consists of two exhaust pipes of different diameters, one transports exhaust gases, and the other carries oxygen-saturated air.

If you have no experience working with heating equipment, but there is a need to resolve the issue of how to improve the efficiency of a gas boiler, contact a specialist. They will perform the work at the highest level, ensuring the most efficient functioning of your home's heating system.