The best double-circuit condensing boilers

The compact and stylish Saunier Duval Thelia Condens 25 A boiler provides efficient heating of a room up to 200 m². The dual-circuit system allows you to organize heating and hot water supply at the same time. At the same time, a summer mode is implemented when only the DHW circuit operates. This eliminates the cost of purchasing and servicing additional electric boilers or geysers between heating seasons. The eBus electronic bus allows for the integration of several compatible boilers into a single system, and also makes it possible to connect a large number of additional control devices. The operation of the device is controlled by built-in systems. DHW activation is carried out automatically when the tap is opened, without the need for preliminary ignition. Separate sensors monitor the level of draft and gas pressure, heating temperature and the presence of flame, which makes heating comfortable and safe.

Saunier Duval Thelia Condens 25 A has increased efficiency (108.5%), which is achieved by technology for recycling thermal energy (condensation type). The aluminium-silicon alloy heat exchanger has balanced thermal conductivity and fusibility. The boiler allows you to reduce gas consumption by 10 - 15% and, accordingly, save money, as well as very quickly (about 2 seconds) reach the required temperature regime - the “Hot Start” function. A closed combustion chamber requires installation in a confined space without natural ventilation, for example, in basements or storage rooms. Processed products are discharged to the street, from where draft is provided by connecting a two-level air duct. This is especially important for a private house or apartment, because it is very difficult to regularly ventilate in winter.

The condensing gas boiler Beretta CIAO GREEN 25 CSI has an efficiency increased to 107.2% and is capable of heating residential and non-residential premises with an area of up to 160 m². The second circuit is responsible for hot water supply and can operate independently in the summer. The closed combustion chamber is equipped with a secondary heat exchanger, which increases efficiency by using the energy of steam released as a result of fuel combustion. This is an innovative approach to the heating system, which not only saves money, but also provides faster and more stable heating. The equipment does not burn oxygen, since the air flow is taken from the street through the chimney. The room may be completely devoid of ventilation. Given its compact dimensions, the condensing boiler can be installed in small niches, basements, boiler rooms, warehouses, private houses and apartments.

The boiler is equipped with automation that controls all processes - starting and stopping heating, maintaining the temperature by changing the flame modulation. The user needs to select a comfortable climate level, and the system will do the rest itself. Individual sensors are responsible for process safety. It provides protection against overheating and melting of the heat exchanger in the event of a lack of water, as well as freezing of the liquid in the circuit, which will preserve the functionality of the circulation pump. Brand development - SARA mode, which automatically controls temperature conditions based on thermostat readings. It allows you to achieve a balance between efficiency and economy, and will also be useful if the owners are absent for a long time.

The Bosch Condens 2500 WBC double-circuit boiler operates on the principle of recycling condensate formed after combustion of the gas mixture. The released vapors enter an additional heat exchanger, giving it their heat. This allows you to achieve very high efficiency (110%), save on utility bills and quickly heat water in heating and hot water circuits. A condensing boiler can be installed in residential areas, confined spaces without ventilation, since it does not burn oxygen, and the air supply comes from the street. The hot water supply system, which can withstand pressure up to 10 bar, deserves special attention. This will allow you to install pipes with the connection of several water points, even if you go up to the second or third floor. The system is also compatible with more viscous liquids, for example, antifreeze, which will prevent freezing if you need to urgently turn off the boiler for an indefinite period of time in winter. Built-in automation independently controls the burner power, simulating the flame in the range of 12 - 100% to ensure uniform heating when water consumption increases.

A closed combustion system prevents carbon dioxide from entering the living space, and flame control completely turns off the fuel supply when extinguished. The boiler has all the necessary safety measures - protection against overheating and freezing, lack of draft and insufficient gas pressure. Built-in automation and sensors are controlled by the proprietary EMS bus. Unfortunately, it is not universal and provides the connection only of compatible devices to expand capabilities, for example, remote access and control via a smartphone, and the integration of the boiler into the Smart Home system.

The BAXI Duo-Tec Compact E 24 condensing boiler operates in autonomous mode and provides heating for rooms of approximately 165 m². Operation does not require constant monitoring. It is enough to select the heating temperature taking into account seasonal climate changes twice a year (winter / summer) using mechanical buttons and a display. The boiler is equipped with an independent hot water circuit for summer mode, which operates separately from heating. The burner power changes automatically (adaptive control system - GAC) when consumption increases, for example, when the kitchen mixer is additionally turned on.

The automation can be powered from a 230V household network or solar energy when the appropriate module is connected. The manufacturer offers a ready-made programmer and optional add-ons - thermostats, external and internal sensors, which will allow you to adapt the heating system to the room and conditions, and create a weekly schedule based on user requirements.

All heating processes take place in a closed combustion chamber using fuel recycling technology. This made it possible to increase efficiency to 108.8%, and accordingly improve heating efficiency and reduce gas consumption, which at a maximum is only 2.61 m³/h. The boiler will provide heat to commercial and warehouse premises, apartments and small private houses, even in the absence of external insulation of the facade.

Installation does not require special conditions - large free space or a ventilation system. Each process is controlled by an electronic control unit. It monitors the presence of flame and draft, eliminates overheating or freezing of water in heating and hot water circuits.

The Hotpoint-Ariston Cares Premium 24 double-circuit boiler copes well with the functions of heating and supplying hot water in warm and cold winter conditions. Its power covers an area of about 188 m², so installation is possible both in a multi-room apartment and a small private house. The water in both circuits quickly warms up due to the use of two heat exchangers and the condensation type of gas processing. The manufacturer used an open combustion chamber, which requires compliance with certain standards during installation, as well as regular ventilation of the room.

The advantages include independent operation of the hot water supply circuit in the summer and compatibility with water heated floors, which is important for rooms on the ground floor and families with children.

The condensing boiler is equipped with built-in protection modules against all common failures - flame extinction, freezing, heating, lack of water. But Ariston developers went further and introduced the Bus BridgeNet control bus to connect additional devices. In this way, you can organize remote control through the Ariston NET application, which is available for smartphones and PCs. The interface is compatible with programmers and zone modules, which allows you to program operating modes for a whole week depending on the temperature conditions in a certain room or area of the house.