According to statistics, in order to create autonomous heating in a home, most European purchase gas heating systems, which are rightfully considered the most economical and environmentally friendly.
Modern industry offers a huge selection of boiler equipment, which differs in many parameters, among which the most common is thermal power, functionality, method of installation and removal of exhaust gases. This publication will focus on hot water gas boilers, which have some design differences from traditional heating installations. We are talking about boiler equipment of condensing and parapet type.
Energy from steam condensation
To understand what a gas condensing boiler is, you must first consider the principle of operation of a traditional boiler installation. When gas is burned, heat is released, which heats the heat exchanger, and, accordingly, the coolant passing through it. After that, the heated coolant enters the radiators, where heat exchange takes place between the air and the coolant, and the combustion products are removed through the chimney.
From the school chemistry course, everyone knows that combustion is an oxidation process that occurs with a large release of thermal energy. When the gas-air mixture is burned, carbon dioxide and water are released, which is in a vapor state. It takes a huge amount of energy to turn water into steam.
The principle of operation of a condensing gas boiler is to convert the water vapor in the combustion products of the fuel back into water. During condensation, the steam gives off the accumulated heat to the surface of the heat exchanger.
It works like this: the return from the heating system enters the condensing heat exchange chamber of the boiler, through which the exhaust gases pass. The temperature of the coolant coming from the system is much lower than the temperature of the water vapor from the combustion products. The steam condenses on the walls of the heat exchanger, giving off the accumulated thermal energy to the heat carrier, which, being warm, enters the primary heat exchanger, where it is mainly heated to the nominal temperature.
The heated coolant is returned to the heating system, and the condensate is discharged through the drainage into the sewer. The acidity of the condensate, as a rule, does not exceed 3.5 units: its discharge into the sewer does not violate the established standards.
For boilers of this type, the efficiency reaches up to 98%, with lower fuel consumption (compared to traditional installations with the same technical parameters).
The efficiency of the boiler depends on the temperature of the coolant entering the boiler equipment: the lower it is, the higher the efficiency of the device. The most efficient operation of this device becomes at temperatures of direct and reverse flow of the coolant 40/30°C.
In connection with the huge range of heating equipment presented on the European market of climatic equipment, many of our compatriots are interested in the question: “What are parapet gas boilers?”
Despite this somewhat tricky name, these are completely non-volatile boiler units with a sealed combustion chamber, which are a kind of symbiosis of a gas boiler with a convector. The scope of such equipment is extensive: from industrial premises to heating city apartments and private houses, which do not provide for a stationary chimney. The removal of combustion products and the supply of air necessary for normal combustion of gas is carried out through a coaxial chimney.
Since this type of heat generators is non-volatile, it will be used only in heating systems with natural circulation of the coolant.
The device of the parapet boiler unit:
- Housing made of thick steel. An easily removable decorative casing with an inspection door is installed on it. Thanks to perforation, this heater, not connected to the heating system, performs the function of a convector.
- Burner block with gas valve. The unit consists of a main and a pilot burner and is mounted on an easily removable frame structure. The pilot burner includes a thermocouple and a spark electrode.
- Sealed combustion chamber.
- Heat exchanger with copper coil.
- Coaxial chimney through which exhaust gases are removed and street air enters.
- Block of non-volatile automation and regulation.
This type of installation is equipped with a thermometer, a piezo ignition system and a smoke and air unit.
A distinctive feature of parapet heat generators is the design of a heat exchanger with a copper or steel water heating coil. Spiral turbolizers are installed in the inside of the heat exchanger, which are designed to reduce the speed of the exhaust gases. This design allows you to significantly increase the contact of heated gases with the surface of the heat exchanger, and, consequently, heat transfer.
How to adjust the operation of a gas installation
Many owners of heating equipment ask how to adjust the parapet boiler? We strongly do not recommend adjusting the boiler yourself. Please note that this manual is for informational purposes only.
Immediately make a reservation that interference in the operation of gas equipment is prohibited by law in our country. Its independent adjustment of work can lead to a decrease in efficiency, equipment failure and other undesirable consequences. Condensing boilers must be adjusted by specialists who are authorized and experienced in this type of activity.
The regulation of the boiler, as a rule, consists in setting the gas valve. On the burner block (under the decorative panel) there are two adjustment screws: adjustment of the maximum and minimum gas pressure.
- On a cold boiler, start the pilot burner.
- Set the first mode.
- If the boiler does not start, then turn the minimum pressure screw (see the location in the passport) before starting.
You have adjusted the start of the boiler. The cutoff is adjusted in the same way.
The condensing heat generator is adjusted using a gas analyzer, the probe of which is installed in a special chimney socket. The maximum and minimum power is regulated by turning the damper on the gas valve, based on the readings of the gas analyzer: at maximum power, the content of carbon dioxide in the flue gases should not exceed 9.5%; residual oxygen — no more than 4%.
Demanded models of heat generators
Today, in the domestic market of climate technology, you can easily find parapet boiler equipment from several European, Ukrainian and European manufacturers. The consumer quite often has a problem with the choice. So, a double-circuit parapet gas boiler: which manufacturer is better?
AOGV 13 P DV “ROSS” is a double-circuit heat generator designed to create autonomous heating and hot water supply in domestic and industrial premises.
This model has a power of 13 kW, which is enough to heat a room of 100 m2. Features of this model: steel heat exchanger; reliable Italian automation; connection of the system from any side, it can work on both natural and liquefied gas. Small dimensions allow installation of the unit in any convenient place, but no further than 5 m from the outer wall. DHW capacity — 4l / min. Efficiency — 90%; fuel consumption 1.4 m3/h Cost — 230 $.
AOGV 12.5 PV “Mayak” — a double-circuit boiler unit, with a thermal power of 12.5 kW.
Connection of the heating system — universal (left — or right-hand), gas supply only on the right. This device can be mounted on a wall, on a floor, and the small sizes allow to install it under a window sill. DHW capacity — 4.1 l / min; Temperature limits in the heating circuit — 40/90 ° С. Efficiency — 90%. Gas consumption 1.4 m3/h The average cost is 190 $.
Aton Compact 12.5 MV — Europe. This dual-circuit model has become quite popular, thanks to the reliable German automatics Mertik Maxitrol and high build quality.
The body of the Aton Compact 12.5 MV boiler unit is covered with powder enamel, which reliably protects it from corrosion and makes it look attractive. Installation power 12.5 kW; fuel consumption no more than 1.4 m3/h; DHW capacity — 300 l / h. Efficiency 90%. The average cost is 180 $.
Choosing the best model and manufacturer is a matter of taste and financial condition of the user. But, more of our compatriots believe that the heat generator AOGV 13 P DV “ROSS” is the best of the parapet models.
If you decide to purchase condensing boiler equipment for heating and creating hot water at home, we recommend that you familiarize yourself with the most popular models.
Vaillant AtmoTEC plus VUW 200–5 is a wall-mounted condensing double-circuit gas boiler from the famous German manufacturer Vaillant Group.
A feature of this model is the lamellar design of the heat exchanger in the DHW unit, which eliminates the appearance of scale. The copper main heat exchanger is coated with Supral, which significantly increases heat transfer. Burner material chromium-nickel steel. The device is equipped with an LCD display. The thermal power of this model is 22.2 kW; DHW — 9.6 l / min; Efficiency — 98%; Cost — 53.50 $.
Chaffoteaux TALIA GREEN EVO SYSTEM 12 FF is a 13.3 kW condensing heat generator. Designed for autonomous heating and hot water supply in apartments and private houses without a stationary chimney.
A feature of this model is the highest efficiency (99%), efficiency (up to 30%), multifunctionality and automation. This unit can work with an indirect heating boiler. Power consumption 105 W. The average cost is 570 $.
BAXI DUO-TEC COMPACT 24 GA is a two-circuit turbocharged model with a closed combustion chamber, made in Italy.
A feature of this device is the ability to adapt to the quality of the fuel. The boiler is equipped with a stainless steel burner with preliminary gas-air mixture and adaptive flame control, due to which a reduced composition of CO and NOx is observed in the combustion products. The efficiency of the installation varies, depending on the mode of operation.
97.6–107.6%. The average cost is 600 $.
Based on user feedback, the Vaillant AtmoTEC plus VUW 200–5 is the best condensing boiler in its class.
Tip: making the right choice of a heating device is a rather difficult task, especially for a person who has not encountered these devices. In any case, before purchasing a gas boiler, consult a professional.