How to choose a gas wall-mounted double-circuit boiler: what to look for + what the market offers
You can achieve some independence from utility services if you install equipment such as a gas wall-mounted double-circuit boiler, which solves the problems of heating and providing the house with an autonomously functioning hot water system.
The article we presented shows the characteristics that you should pay attention to when choosing a unit. We have described in detail the structure and design features of gas double-circuit equipment. To make the choice easier, we have listed the leading manufacturers in the segment.
The content of the article:
Connection diagram for boilers with two circuits
Main gas, to which urban residential buildings, enterprises and public institutions are connected, is the cheapest fuel. Even taking into account paperwork and approvals from several authorities, the installation of gas boilers is justified. A correctly selected model will be able to service both the heating system and supply sanitary water.
The boiler is installed in a place convenient for maintenance. With proven connection diagrams The article we recommend will familiarize you with the dual-circuit gas unit. It is necessary to ensure a safe gas pipe connection that meets installation standards and to bring the chimney outside to transport combustion products.
Cold water is supplied to the boiler; after heating (when a certain temperature is reached), it is transported to water collection points, the main ones being the shower stall, bathtub, and kitchen sink.
The intra-house heating network is a closed circuit with a circulating coolant that serves the “warm floor” system, radiators, convectors and heated towel rail in the bathroom.
An alternative to installing a double-circuit model is to install a 1-circuit boiler + BKN kit, where indirect heating boiler serves the hot water supply system. This scheme is good because there is always hot water at the required temperature in the taps.
In dual-circuit models, the heating system and hot water supply inside the device do not intersect, which provides its own bonuses. For example, not a universal filler – water – is used as a coolant, but a special solution.
Advantages of wall-mounted double-circuit boilers
Saving space in a cramped apartment is just one advantage of boilers with two circuits (DC).There are a number of advantages due to which wall-mounted indoor heating units are chosen as the main equipment for heating water and organizing household autonomous systems.
Here are some reasons to purchase a 2-circuit wall model:
- This is equipment that is maximally equipped for heating water and its further distribution, and does not require the connection of additional devices;
- The recreation center can be installed in a hallway equipped with windows or a ventilation vent, or in the kitchen; it does not require a separate room;
- due to their compact size, boilers are mounted in niches or corners, or hidden in kitchen cabinets;
- automatic equipment allows you to maintain the required water temperature, which does not depend on pressure or air temperature fluctuations;
- modern models are characterized by high efficiency and cost-effectiveness;
- one of the conditions for installation in a residential building (apartment) is met - a low noise level that is comfortable for residents;
- the cost of household models can be called moderate, and the same applies to after-sales service.
For wall-mounted modifications with a closed combustion chamber, a simplified type of chimney is installed: instead of a vertical one passing through the roof, equip a coaxial option, brought out through a nearby wall.
In apartment buildings, the smoke duct is constructed in the form of a curved elbow from modular elements or corrugation and is connected to the public chimney.
What to look for when choosing equipment?
Depending on the requirements for the equipment, the selection criteria may differ, but in any case it is necessary to understand the technical characteristics, functionality, and even such seemingly trifles as the exact dimensions.
First, let's look at the main technical nuances.
Thermal power and performance
The main function of a gas boiler is to increase the water temperature for hot water supply and heating, so the power parameters must be considered first. They can be found in the technical data sheet of the device. To find out whether the boiler is suitable in terms of power for your home/apartment, you should make simple calculations.
It is generally accepted that for every 10 m² of serviced space, 1 kW is required for normal heating. But these are average figures applied to housing with good thermal insulation. If we take into account climatic conditions and the need for heating water for hot water supply, then the obtained result can be further increased by 35-40 percent.
The more powerful the equipment, the more productive it is. The performance indicated in the data sheet makes it clear how many liters of water are heated in 1 minute to the desired temperature.
2 parameters are given - for a temperature of 25°C and 35°C. Some people mistake these readings for the outlet water temperature, but this is not the case. This is the difference between the inlet temperature and the already heated water.
Let's assume that the coolant at the inlet has a temperature of 10°C, therefore, at 35°C, water of 45°C will enter the taps. At 25°C the water heats up faster, therefore the heating rate is higher.
If at 25°C the productivity is 13 l/min, then at 35°C it will be about 9 l/min.Of course, the indicated values will be more accurate if the water pressure and gas pressure correspond to the standards that the manufacturer took into account during testing.
Which heat exchanger is better?
The heat exchanger is designed to transfer heat from hot gases (combustion products) to a coolant distributed over two systems. The choice is faced with two types of elements: a pair of separate ones (primary + secondary) and bithermic.
In devices with separate heat exchangers, the primary one looks like a pipe with plates and is located above the gas burners, and the secondary one looks like several wide plates assembled together and having 4 connection pipes instead of 2. The first is responsible for the heating system, the second is for heating water for hot water supply.
If you use a hot water tap, the flow sensor (6) will work, and water, under the action of the circulation pump (5), will flow to the primary heat exchanger, but through the DHW circuit.
The second type - a bithermal heat exchanger - is distinguished by the fact that it serves both circuits: hot water supply and heating.
It has a special pipe design in which water for the DHW circuit moves through the internal channel, and the coolant for heating moves through the external ones. Advantages of a bithermic heat exchanger: saving space inside the housing, simplified boiler design, lower price.
However, when choosing, they often tend to purchase devices with separate heat exchangers for the following reasons:
- elements are less likely to fail due to the formation of scale and sediment;
- the primary heat exchanger is easier to clean and rinse;
- the boiler can be repaired in parts;
- there is no risk of getting burned due to too hot water (the secondary heats only up to 60°C).
If you have a choice between expensive models, we suggest considering condensing type offers, which are more economical and have significantly more power.
The cost of condensing devices starts from 100 thousand rubles. An example is the eco line of the German manufacturer Vaillant.
What types of combustion chambers are there?
It depends on the design of the combustion chamber chimney device and ventilation, so this also needs to be taken into account. The choice is between two types: open and closed, which differ fundamentally.
The open combustion chamber is located above the burner, under the hood, and is connected to a vertically directed chimney. Combustion air is taken directly from the room (kitchen, hallway, boiler room).
In closed-type combustion chambers, air passes through the channel of the coaxial chimney, and gases from the burner are discharged through it. Natural draft does not matter, since a centrifugal fan is used to remove combustion products.
Devices with closed chambers are preferred, although they are more expensive.They do not require a separate chimney, and they also have higher efficiency. Models with an open chamber can be useful for replacing old devices if the installation site is already equipped with proper ventilation and a vertical chimney.
Other Important Selection Options
In addition to the listed design features that affect both the performance and cost of the equipment, there are a number of functions that simplify the management and maintenance of a gas double-circuit boiler.
When purchasing, it is also important to clarify the dimensions of the device itself and the diameter of the required chimney in order to install the boiler in the home, focusing on fire safety standards.
How to choose a double-circuit boiler correctly, taking into account the technical characteristics, is described in the article, the content of which is devoted to this difficult issue.
Review of gas boiler manufacturers
In countries where autonomous gas heating is actively used, the market is filled with products from various companies. Competition is so high that enterprises that cannot withstand it due to poor quality of goods quickly go out of business.
Let's consider best offers from manufacturerswhich are popular and of excellent quality.
Boilers from the Italian company BAXI
The BAXI company was founded just under a century ago – in 1924. Today it is part of the BDR Thermea holding and specializes in the production of wall-mounted gas equipment. The well-known lines of boilers ECO, MAIN, NUVOLA, LUNA have proven themselves to be reliable and flawlessly functioning equipment.
Homeowners with a lack of free space for installing a gas boiler will be interested in the models of the ECO Four series. These are ultra-compact devices, with a height of only 73 cm and a width of 40 cm. The power is limited to 24 kW, but it is enough to heat a house with an area of 200 m².
Among the presented models are single-circuit and double-circuit, with different types of combustion chambers. A mandatory element is an LCD display that displays important parameters.
German quality of Bosch thermal technology
The Bosch company, which emerged in the century before last, is known in many manufacturing areas, including the manufacture of gas heating boilers for domestic use. Double-circuit wall-mounted devices, which are produced in many parts of the world, are distinguished by high technology, compactness and ease of operation.
Let's take a closer look at what makes the 6000 series boilers good:
The German manufacturer pays great attention to the compactness of its devices and is working on producing economical models. We are pleased with the new condensation type products, which allow increasing efficiency through the use of condensate.
We can say that the Korean company Navien is slowly but surely conquering the whole world. Having started production of gas heating devices in 1978, it has been supplying equipment to more than 30 countries.
The Asian manufacturer is known for developing environmentally friendly technologies and caring about environmental protection. Part of the profits from sales goes to our own environmental fund and to insulate housing for the poor.
A bonus for lovers of comfort is a convenient remote control with an LCD display, with which you can adjust the temperature of the hot water and set an economical fuel consumption mode.
In addition to the listed manufacturers, it is worth paying attention to wall modifications of the Italian brands Hermann, Beretta, Weller, Feroli, as well as Chaffoteaux (France), Airfel and Demarad (Turkey), Protherm (Czech Republic), Aton (Ukraine), Gaslux and NEVA Lux (Russia) ).
Rules for installing and connecting wall-mounted gas boilers are given in next article, the contents of which we advise you to familiarize yourself with.
Conclusions and useful video on the topic
You can learn about the design features, as well as the nuances of installation and use of gas double-circuit equipment with wall mounting, from the presented video materials.
Video #1. User review of the NAVIEN 24 model:
Video #2.About the technical characteristics of Protherm Lynx 24:
Video #3. Comparative characteristics of 1- and 2-circuit boilers:
When choosing a gas wall-mounted boiler, you need to focus not on the appearance, which is identical for many models, but on the technical capabilities of the models. It is important to take into account both the area of the home and the pressure in the gas main and cold water supply network.
Even new models require maintenance, so it would be useful to check the availability of a workshop capable of providing service.
Tell us about how you bought a wall-mounted gas unit to install in your house/apartment. Share the reasoning behind your choice. Please write comments in the block below, ask questions, post photos on the topic of the article.
I installed a Westen double-circuit boiler in my apartment on the ground floor 8-9 years ago. Compact in size, hidden in a closet, the chimney opens into a common ventilation shaft for the house. Enough for heating in three rubles and a warm floor in the kitchen located above the basement. Over the years of operation, a block burned out that regulates the boiler shutting down if there is no water. Sometimes the water pressure drops. In general, it’s a good thing, in our city we don’t have a centralized hot water supply, but it’s always warm and hot water, I recommend it to everyone who has the opportunity.
We also have a double-circuit boiler in our house. We settled on a wall-mounted Ferolli, with a closed combustion chamber. Set it and forget it, no problems. Convenient to use. The water temperature can be easily adjusted. We immediately signed a contract with the company for 3 years. Once a year they will come and clean it. The main thing is that the ventilation is with normal draft.
In 2012, we purchased a Baxi Mainfour 24 with an open combustion chamber. It has been running for 7 years now and has only had one problem. The sensor that controls the heating of hot water has broken down. The display showed one temperature, but in reality it was almost boiling water. I replaced the sensor in 2015. At the moment everything is fine. Consumes little gas. We have a wooden house, 50 sq.m., so in the winter months only 270-280 cubic meters of gas are consumed. Very economical and the house is warm, 25-26 degrees.
It's amazing how large the selection of gas boilers is. And most importantly, at least someone will write something bad about everyone. I thought about Ferroli, but they write that now they are assembled by the Chinese and the quality has dropped accordingly. I'll probably take the Westen Quasar.