The best double-circuit condensing gas boilers

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 treatment. The manufacturer used an open combustion chamber, which requires compliance with certain standards during installation, as well as regular ventilation of the room.

Among the advantages, we can highlight the 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.

The Czech company Protherm is part of the Vaillant Group, which specializes in the production of high-quality heating equipment. For heating large apartments and private houses, the brand’s portfolio includes a remarkable condensing “double-circuit” Puma.

Protherm Puma Condens 24/28 MKV-AS/1 is a gas boiler with forced draft and a closed combustion chamber. The primary heat exchanger of the unit is made of aluminum-silicon alloy, the secondary one is made of stainless steel. The first circuit is used for heat generation. The advantages of the model include the highest efficiency (over 107%), an 8-liter expansion tank and the presence of a circulation pump with frequency control - it allows you to extremely accurately maintain the temperature regime.

The preparation of hot water supply for household needs is entrusted to a secondary plate heat exchanger. The water in it is heated from 35 °C to 55 °C, and it is supplied in a volume of over 13 l/min. The “hot start” function helps to set up the supply of hot water literally after 2 seconds. after the start of water collection.

The boiler has simple and intuitive control using touch buttons on the front panel of the housing. There is also an info display on which codes for possible equipment malfunctions can be displayed. And via the eBus, the device can easily be integrated with other heating sources ( solar collectors, heat pumps, etc.). At the same time, the model supports the possibility of installing weather-dependent automation and/or a room thermostat.

The condensing gas boiler Bosch Condens GC2300i W 24/30 C provides heat for residential and industrial premises with a “square area” of up to 192 m², and is also used for preparing hot water.

The model has a dual-circuit layout. The main heat exchanger of the boiler is made of magnesium-aluminum alloy and has an increased heat transfer area. This ensures high efficiency of the unit in thermal generation mode (over 103%). For the heating circuit, the boiler heats the water to a temperature of 82 °C. The low-noise frequency-type circulation pump automatically adjusts the speed in accordance with the hydraulic resistance of the heating system, thereby ensuring proper supply of coolant to the radiators and saving electrical energy consumption.

To prepare hot water, the boiler is equipped with a plate heat exchanger. Its supply to the DHW circuit is possible in a volume of over 14 l/min. This is quite enough for full use of two bathrooms at the same time. Note that the presence of a summer operating mode allows you to use the boiler for preparing hot water regardless of the heating circuit.

The heater of the unit provides modulation of the burner flame from 12.5 to 100%, and the temperature setting is carried out with an accuracy of 0.5 °C. A separate line marks the intuitive boiler control panel with an LCD display. Optionally, it is possible to remotely configure the boiler operating parameters from a smartphone, but for this you will need to acquire a “smart” EasyControl thermostat or a smart controller CW 400.

In Western European countries, heating boilers from Vaillant consistently hold the title of popularity. The ecoTEC pure VUW 286/7-2 model, designed to serve areas up to 192 m², was no exception to the rule.

The unit belongs to the category of double-circuit condensing gas boilers. Thanks to the ability to extract and usefully use the latent heat of condensation of water vapor, the model has a high efficiency of over 105%. The boiler was equipped with a closed-type turbocharged combustion chamber, a modulating burner with a power range from 35 to 100%, and a frequency-controlled pump to ensure coolant circulation.

In the heating circuit of the boiler, pressure can be maintained at a level of up to 3 bar, in the hot water supply system - up to 10 bar. Hot water is produced in a plate heat exchanger, with a capacity of up to 13.5 l/min. This amount of water is enough for the normal operation of two water points and serving the needs of a large family.

The boiler received a microprocessor control circuit with a push-button panel and an information display. External control modules can be connected to it via the eBus communication bus. The model impresses with its high efficiency of heating and hot water preparation, efficiency, excellent reliability of components and assemblies - this is exactly what you want to see in an advanced gas boiler.