How to choose a gas wall-mounted single-circuit boiler

When it comes to insulation and heating, selecting the ideal gas wall-mounted single-circuit boiler for your house is essential. Selecting the one that best fits your needs can be overwhelming with the abundance of options available on the market. We’ll break down the important elements you need to think about in order to make an informed choice in this guide.

The first thing you should do is determine how much heat your house needs. Take into account elements like your home’s size, the number of rooms you require heating, and the local climate. For efficient and reliable warmth throughout the house, a boiler with a higher heating capacity may be necessary in larger homes with more rooms or in colder climates.

Next, consider what you require for hot water. Certain gas wall-mounted boilers can supply hot water for your showers and faucets in addition to heating. Be sure the boiler you select has the capacity to meet the needs of your household if you’re looking for one that can handle both heating and hot water.

Another important thing to think about when choosing a gas boiler is efficiency. Models with greater efficiency can lower your carbon footprint and help you save money on energy costs. High Annual Fuel Utilization Efficiency (AFUE) ratings on boilers are desirable as they show how much of the fuel they use is converted to useful heat. Long-term savings can be substantial if an upfront investment is made in an efficient boiler.

Additionally, take note of the boiler’s dimensions and installation specifications. Selecting a gas wall-mounted boiler that fits your available space and can be installed safely and easily is crucial because these boilers come in a variety of sizes and configurations. To guarantee a seamless installation process, take into account elements like ventilation, piping, and clearance requirements.

What are the single-circuit wall-mounted gas boilers

The focal point of the local heating system is a wall-mounted, single-circuit gas boiler that is only intended for space heating.

Its smaller dimensions—55 to 90 cm in height and 40 to 45 cm in width—as well as its lighter weight—30 to 75 kg—set it apart from its counterparts and enable wall mounting. No matter the setting—a pantry, restroom, kitchen, attic, or even the attic—this kind of unit works well there.

In comparison to floor boilers, wall-mounted gas boilers have a much lower nominal heat output: domestic boilers range from 10 to 42 kW, while industrial boilers range from 46 to 100 kW. However, it is more than sufficient to heat the majority of average-sized residential and commercial buildings, ranging in size from 60 to 800 m 2.

If this is still insufficient, you can increase the power range—from 50 to 1000 kW—by cascading multiple compatible models together.

Device and principle of operation

A wall-mounted boiler is similar to a column in many ways, except that it heats coolant that is constantly circulating rather than water that is flowing.

A minimum of four operating units are included in every single-circuit boiler:

• A combustion chamber (furnace) equipped with a burner;
• The primary heat exchanger is of the plate type;
• exhaust gas (fumes) removal system;
• mechanical/electronic control unit.

In hinged models, the gas outlet is created via a coaxial (side) chimney, which is typically included in the basic kit. Contemporary units also feature an integrated expansion tank, multifunctional automation, a circulation pump, etc.

Regardless of changes, the same system governs how all gas boilers operate:

1. The burner doses the air-gas mixture into the furnace for combustion.
2. The released energy is transferred to the heat transfer medium via a heat exchanger.
3. Circulating liquid (water, antifreeze) carries heat to the radiators.
4. When it has cooled down, it is returned to the boiler – the cycle is repeated again.

Therefore, single-circuit wall-mounted models "by default" have all the components needed to connect to the general heating system, even with their compact bodies. However, you will also require the installation of a storage water heater, or boiler, in order to completely supply the house with hot water with their assistance.

Organization of an autonomous system of hot water supply (HWS)

An indirect heating boiler is a type of thermal tank that uses some of the heat energy from an external source to prepare hot water.

Wall-mounted boilers are unique in that they are typically made with the right connections and are initially intended to work in tandem with the boiler. Because many models have unique decorative panels, you can stack units on top of one another without having to fasten them to the wall.

In boilers with a boiler (as opposed to two-circuit analogues), the priority of DHW is only given during the primary heating.After that, the coolant is distributed so evenly that the change in heating power is imperceptible to the occupants of the house. The second circuit is connected as usual, in parallel to the heating.

How to select a room thermostat to reduce monthly heating costs by up to 30%

Reviews of owners of hinged heating boilers: the main pros and cons

It is common knowledge that articles in the store that promote products and the advice of consultants can have biases, so it is important to thoroughly examine the experiences of actual owners.

Advantages	Disadvantages
low cost – single-circuit wall-mounted models are considered the cheapest type of gas boiler	short life – the unit is made of lightweight metals, so it is not designed for a long service of more than 15 years
reliability – Unification of the technical component guarantees the absence of serious malfunctions and breakdowns. In practice, the number of service calls to the owners of mounted models is approximately equal to the number of calls to the owners of floor standing boilers	difficulty of maintenance – compact assembly makes it difficult to access the units for preventive inspection and repair
safety – all mounted units are equipped to varying degrees with automatic control and protection elements (against overheating, system freezing, circulation pump stoppage)	energy dependence – due to the presence of a circulation pump, complex automation, often – turbine, hinged models require connection to the power grid. Energy-independent options to date there is no
free location – such boilers can be installed in the neighborhood of furniture and appliances, including the following. ч. with stoves
higher efficiency – despite the more compact size, the technology, alloys used and more advanced automation allow to achieve on average 2-5% higher efficiency compared to floor standing counterparts

Creating supporting documentation and obtaining a permit from the Gas and Technical Supervision Agency are prerequisites before installation. It’s also crucial to remember that, when supplying liquefied gas (LPG), gas boilers on the ground floor cannot be placed in hallways, restrooms, basements, balconies, or spaces without ventilation.

The precise specifications needed to install a gas boiler in a private residence

Selecting the ideal gas wall-mounted single-circuit boiler for your house is essential if you want economical and effective heating. To find out the boiler’s capacity, first take into account the size of your house and your heating requirements. Efficiency ratings, such as AFUE, show the amount of heat that a boiler transforms from fuel into heat that can be used in your house. For optimum performance and safety, look for features like sealed combustion chambers and modulating burners. When making your selection, don’t forget to take warranty coverage, maintenance requirements, and installation ease into account. You can choose a gas boiler that maintains energy costs low while supplying dependable warmth by carefully considering these factors.

How to choose a gas wall-mounted single-circuit boiler for a private house

There is a large selection of wall-mounted gas boilers available for heating. It is sufficient to comprehend what actually results in this or that engineering solution in order to focus the search for the best option, rather than needing to fully comprehend all the subtleties of how the equipment operates.

Convection, low-temperature or condensing

A single-circuit mounted gas boiler’s efficiency is determined by how the heat energy produced by fuel combustion is used. Based on this characteristic, all units are divided into three groups:

• convection – Standard models, which receive energy only from direct combustion of gas, while they constantly heat the coolant to high (70-80 ° C) temperatures, regardless of how much heat is needed at the moment, so most of it remains unclaimed and leaves together with red-hot (130-160 ° C) smoke;
• low-temperature – have the same design as traditional boilers, but in them the contact between the cold walls of convective tubes (by shielding) and the exhaust products of combustion (100-120 ° C) is eliminated, so they allow cooling of water (20-40 ° C), without the danger of condensation;
• condensing – work best when the water temperature in the heating system is below the "dew point" of gas (10-50 ° C), they are equipped with an auxiliary heat exchanger (economizer), which accumulates the heat of water vapor, not allowing it to escape with the smoke, because of which the latter is cooled (70-80 ° C).

The more recent models are obviously more costly than the standard convection ones, but they operate at a higher profit margin: low-temperature boilers are typically 15-20% more efficient, while condensing boilers are 25–40% more efficient. Furthermore, the unit itself has a less detrimental effect on the environment the cooler the exhaust smoke.

Distinctions and sizing standards for condensing gas boilers

Material of the primary (high-temperature) heat exchanger

Heat transfer from the burner to the heat transfer medium is handled by the primary (high-temperature) heat exchanger. Heat exchangers composed of thin, light metals, such as copper and steel (enameled or stainless steel), are fitted with all wall-mounted boilers. The popular sturdy cast iron is too hefty for this kind of apparatus.

Steam is not collected using conventional heat exchangers because it reacts with smoke to form acid and erode walls. For this reason, the second (cold) heat exchanger in condensing boilers is constructed of a metal that can withstand the aggressive effects of acids, such as silumin, an alloy of silicon and aluminum.

Which heat exchanger is better for the boiler? There is no clear answer; it all depends on the metal’s quality, thickness, processing technique, and temperature.

With copper heat exchanger

The best material for wall-mounted boilers is thought to be copper because it is pliable, lightweight, and resistant to corrosion (it doesn’t rust). Copper heat exchangers heat up quickly because of their low inertness; however, if they are heated intensely over an extended period of time, they may burn out.

Thus, boilers with copper heat exchangers have more benefits than drawbacks. However, due to their relative cost, domestic manufacturers prefer to use more affordable steel to make their heat exchangers, so you’re more likely to find them in imported production models. Copper heat exchangers have a 14–16 year service life.

With steel heat exchanger

Steel is more resilient to physical and thermal shocks and pressure spikes that occur during transit. Steel heat exchangers are simple to produce, which contributes to the unit’s eventual lower cost.

Steel heat exchangers are less efficient because a significant portion of the energy is used only to warm the walls. Their service life is often limited to 12–14 years, and they are more prone to corrosion. Manufacturers use a trick to extend it: they coat the steel in copper and then coat it with a layer of sturdy, heat-resistant enamel.

Type of combustion chamber and flue gas removal system

The supply of the required amount of air into the furnace and the subsequent use of exhaust flue products go hand in hand with the operation of every boiler unit.

These procedures are executed in gas units in two ways:

• atmospheric model – equipped with an open combustion chamber, air intake and smoke extraction is carried out through vertical ducts (natural draught);
• turbo model – has a closed combustion chamber, air intake and smoke extraction is done by a powerful fan (forced draught).

Open combustion chamber and natural draught

An old-fashioned device that uses oxygen from the space it is in is an atmospheric gas boiler with an open combustion chamber. Thus, the first thing that will need to happen is that the room will need to be regularly ventilated or have a ventilation system installed in order to maintain stable operation.

It is worthwhile to highlight its affordable price and silent operation, as the only sounds it makes are the "hum" of the flame and the flowing water.

Closed combustion chamber and forced draught (coaxial chimney)

More sophisticated models, which make up over 90% of the market. A turbine boiler with a closed combustion chamber works on a different principle: it removes smoke from the interior through an internal pipe and uses an external chimney to absorb oxygen from the street. This completely stops any air intake from the room, so you don’t need to worry about ventilation.

Because it keeps the heated components away from the gas, this design ensures that there won’t be any fuel leaks or other emergencies. Its hermetic casing prevents the heated components from coming into contact with the gas, and the combustion chamber is isolated from the room and only connected to the chimney. Minuses: supplementary fan noise.

While most natural gas units have an open combustion chamber, forced gas units typically have a closed one. There are, however, some exceptions. Thus, among the boilers with an open combustion chamber, there are unique models from the Japanese manufacturer Rinnai that have an exhaust smoke removal fan installed at the inlet.

Varieties of gas burners by the degree of flame regulation

The "heart" of any gas boiler is the gas burner, which controls the intensity of fuel combustion while starting and maintaining the process. The degree of flame regulation separates three types of burners in total:

• single-stage – always operate in one position at 100% capacity, maintain the temperature of the heating medium at a fixed level through periodic switching on and off.
• two-stage – They function in two modes: 30/50 % (depending on the model) and 100 % power, they are actuated by electric ignition and never switch off, so when the water temperature reaches the set value, the boiler switches to the economical mode (until partial cooling down);
• modulated – They precisely adjust the desired power by 10-100%, their work is controlled by a complex microprocessor automation, and the modes change depending on the current parameters of the heating system: changes in pressure in the main pipeline, temperature of the coolant, etc.

Model burners are the most economical and productive. In addition to ensuring a minimum percentage of empty unburned gas, they automatically choose the ideal amount of fuel (in t. ̇. liquefied gas) and smoothly regulate the heating medium heating.

Coefficient of performance (efficiency)

It’s commonly thought that a boiler operating more efficiently translates into more economical gas consumption; however, this isn’t quite the case for wall-mounted models. The actual efficiency of contemporary units has consistently hovered around 91% to 95% for standard units and 101% to 109% for condensing units. Even so, it is still not appropriate to use a few percent difference in efficiency as the primary criterion, particularly when heating 100 m³ or smaller homes.

In this regard, it is preferable to follow the manufacturer’s stated expected fuel consumption in the technical passport rather than its efficiency. The best maximum flow rate for residential boilers with 10–20 kW is 0.9–2.1 m 3 of natural gas or 0.7–1.9 kg of LPG per hour.

Minimum required power

A straightforward formula can be used to determine the necessary output:

Q is equal to S × 0.1,

• Q – required power (kW),
• S – area of the heated dwelling (m²),
• 0,1 – power rate per unit area for an average house with a masonry of 2 bricks and ceiling height of 2.7 meters, located in the climatic zone of the Moscow region.

For instance, Q = 120×0.1 = 12 kW is the amount of power needed for a 120 m² residential house. We also advise setting aside 15-20% of the power in case of frost, so Q is approximately 14 kW.

It is important to consider that the energy consumption of an indirect heating boiler should not surpass 45–50% of the boiler’s overall output when installing one.

How to compute the necessary boiler output precisely Formula, correction factors, and individual calculations

Additional criteria

Apart from the previously mentioned variations, you may take into account additional factors that impact the operational comfort and safety:

• automation functionality – Ideally, the control module controls all the processes itself, from start-up and change of modes to blocking in case of breakdown;
• safety level – every boiler sold a priori complies with the norms, but some have a more complex multi-stage protection system;
• degree of thermal and acoustic insulation – dense lining prevents heat loss (increases the efficiency of the appliance) and reduces noise from the fan and burner;
• antifreeze option – for filling the chemistry. only special units, resistant to aggressive influence, are suitable for substances.

The best known manufacturers and models: characteristics and prices

BAXI ECO Four 1.24

Among other European models, this well-known Italian boiler with an open combustion chamber from the well-liked BAXI ECO line stands out for its affordability, dependability, and durability.

Its hydraulic unit has an automatic bypass, coolant filter, and pressure gauge. The integrated control unit offers self-diagnosis and weather-dependent regulation options. It uses 2.7 m 3 /h (2.0 kg LPG/h) at 24 kW. Copper makes up the main heat exchanger.

Protherm Panther 25 KTO

This model is in the medium class (high comfort); it is practical for daily use as well as for connecting.

There is a closed combustion chamber in the turbo unit. Copper is used for the heat exchanger, internal piping, and inlet/outlet pipes. At the power limit, the burner consumes 2.8 m 3 /h (LPG 2.1 kg/h) of gas with a modulation depth of up to 25 kW.

Vaillant turbo TEC plus VU 242 5-5

Craftsmen have long acknowledged this 24 kW German reference gas boiler as the best turbo unit available in terms of build quality and dependability.

Modern alloys and technologies are used to ensure that German models are always extremely reliable and resistant to any operating condition. It has a copper heat exchanger, an auto-switching circulation pump, an extended list of information codes on an alphanumeric display, and a chrome-nickel steel burner that resists burnout. Maximum fuel consumption: 2.2 kg/h (2.9 m³3/h) for LPG.

The sole drawback is that it is susceptible to voltage variations (it is recommended that you connect to the network via a stabilizer).

Top German gas boilers The market’s most effective, dependable, and useful models

Viessmann Vitopend 100-W A1HB002

An additional citation One of the best gas wall-mounted single-circuit boilers for heating a private home, particularly popular in the EU, is the German representative’s low-temperature unit.

It features an electric and gas network fluctuation protection feature along with a copper heat exchanger and a "smart" controller that can self-adjust. This enables it to adapt to the most dire circumstances. It is fairly economical for a 30 kW capacity – 3.4 m 3 /h (LPG 2.5 kg /h).

Based on operational experience and feedback from owners, all models have been trouble-free for over six years.

Buderus Logamax U072-18

A low-cost 18 kW unit with a copper heat exchanger is made especially to work in typical Russian weather, even during freezing temperatures.

Its affordability, superior design, and economical nature are its main advantages. In Russia, the Buderus service structure is highly advanced and renowned for having qualified specialists in practically every area. The maximum fuel consumption is 2.0 m 3 /h (2.8 kg/h for LPG).

Rinnai BR-UE30

The well-known Japanese model has an impressive 29 kW of power despite its incredibly small size. A copper heat exchanger is another feature of it.

Like all Asian boilers, it has a set of side modules that include a voice navigator, remote access (remote control, Wi-Fi), and automation that is dependent on the weather because it prioritizes the comfort of the owner. Reduce gas consumption to 2.8 m 3 /h (LPG 2.5 kg /h); accurate temperature control aids in this.

Prices: summary table

Wall-mounted single-circuit gas boilers’ comparative rating:

Boiler name	EFFICIENCY, %	Power, kW	Gas consumption, m 3 /h	Price, rub.
BAXI ECO Four Four 1.24	91,2	24	2,7-2,0	37 000
Protherm Panther 25 KTO	92,8	25	2,8-2,1	57 000
Vaillant TEC VU 242 5-5	91,9	24	2,9-2,2	75 500
Viessmann Vitopend 100 W	93,0	30	3,4-2,5	56 000
Buderus Logamax U072-18	92,1	18	2,0-2,8	40 000
Rinnai BR-UE30	92,8	29	2,7-2,5	61 500

Consider your heating needs	Assess the size of your home and the number of occupants to determine the boiler capacity.
Energy efficiency rating	Look for boilers with high energy efficiency ratings to save on gas bills and reduce environmental impact.
Installation cost and complexity	Factor in installation costs and whether your home"s layout suits a wall-mounted boiler.
Brand reputation and warranty	Choose a reliable brand with a good warranty to ensure long-term performance and support.
Compatibility with existing systems	Check if the boiler is compatible with your current heating system and controls.

Selecting the appropriate gas wall-mounted single-circuit boiler is crucial to guaranteeing effective insulation and heating in your house. With so many options on the market, it’s crucial to weigh a number of considerations before choosing one.

First, determine how big your house is and how much heating you require. A boiler that is too big could result in energy waste and higher bills, while a boiler that is too small might find it difficult to heat your space sufficiently. To choose the right size, take into account elements like the local climate, the number of rooms, and the quality of the insulation.

Next, take into account the various boilers’ energy efficiency ratings. Choosing a high-efficiency model can cut your energy costs and your carbon footprint considerably. A high Annual Fuel Utilization Efficiency (AFUE) rating on a boiler indicates how well it converts fuel into heat.

Do not forget to consider each boiler’s installation and maintenance needs. To save time and money later on, go for a model that is simple to install and maintain. Examine the standing of various models and brands to make sure that replacement parts are dependable and readily available.

Additionally, think about the fuel type that best fits your needs and price range. Although gas boilers are widely available and reasonably priced, depending on your situation, other options like oil-fired or electric boilers might be more appropriate.

Finally, remember to account for your financial limitations. Although it may be tempting to go with the least expensive option, weigh the advantages and disadvantages of investing in a higher-quality, more efficient boiler over the long run. It is imperative to keep in mind that optimal boiler lifespan and performance are contingent upon both high-quality installation and consistent maintenance.

In conclusion, careful consideration of factors like size, energy efficiency, installation and maintenance requirements, fuel type, and budget is necessary when selecting the best gas wall-mounted single-circuit boiler. You can minimize energy costs and the impact on the environment while ensuring your home has the best possible heating and insulation by taking the time to carefully consider all of your options.

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