You brought a gas pipeline to a country cottage or installed a container for liquefied propane. The next stage is the choice of heating gas equipment. The task is not easy - the variety of domestic boilers in online stores will be bewildering for any inexperienced homeowner. Accordingly, our goal is to consider the existing types of units and explain how to choose the right gas boiler for heating a private house, cottage or apartment.
What you need to know to select a heater
You can’t just go to the store and buy a gas heating boiler. To select a suitable model, you need to prepare a list of requirements for the unit - to determine the thermal power, the necessary functions, installation method and other initial data.
Which items are on the list:
- Calculate the amount of heat required to heat a cottage or apartment.
- Outline the range of tasks for a gas boiler - it should only heat the building or, in addition, serve as a water heater for household needs.
- Allow space for the installation of a heat generator. The rules allow the installation of gas-powered heating equipment in a kitchen (power up to 60 kW), an attached boiler room or in another separate room located at the outer wall of the dwelling.
- Determine how the boiler is installed - floor or wall. For apartments, only a hinged option is suitable.
- Consider the principle of operation of your heating system. Under the gravitational circuit with the natural circulation of the coolant (the so-called gravity flow), the corresponding non-volatile heater operating without electricity is selected.
- Set the level of automation of the device according to your wishes. Examples of useful functions: maintaining indoor temperature according to a schedule or signals from an external weather sensor, remote control via the Internet, and so on.
- Estimate the prices of various boilers and find out how much you are willing to spend on a gas boiler.
Note. The rules for the placement and connection of gas-using installations intended for heating and hot water supply are described in the publication on the installation of a dual-circuit heater.
Before choosing a new one or changing an outdated gas boiler for heating a private house, we highly recommend consulting a subscription department of Gorgaz (or another management company). Why is this needed:
- In addition to the general rules, regional offices have internal instructions restricting the use of gas equipment; these points should be clarified;
- a new or replaceable boiler must be included in the design documentation, otherwise you run the risk of getting a fine for installation without approval;
- Specialists will help you place the heat generator in the house.
Clarification regarding internal instructions. Gorgazs often introduce their own restrictions, for example, they can prohibit the installation of an atmospheric boiler next to a forced-draft kitchen. The reason is the lack of compensating air flow.
Another example: you want to remove a horizontal (coaxial) chimney from the room of an apartment building, but the office does not agree on this solution, since the protruding pipe spoils the appearance of the facade. To understand all the subtleties, you have to understand the existing varieties of gas heaters, but first ...
We determine the thermal power of the boiler
Surely you know the popular methods for calculating the thermal performance of equipment - by the area or volume of the heated rooms. Allegedly, a 10 kW boiler is taken to a dwelling of 100 square meters, a 200 square meter to a country house.m - 20 kW unit.
It is better not to use these approximate methods, since specific conditions are not taken into account - the climate in the area of residence, the degree of thermal insulation of the building, and so on. We suggest using more accurate calculation methods:
- By specific heat load per square area of the living room, taking into account the location of the room and the number of window openings.
- The same in terms of space.
- A full-fledged calculation according to the SNiP formula, taking into account the thickness and thermal insulation of external building structures.
Comment. All 3 methods are described in detail in a separate guide to calculating the heat load for heating a residential building.
Knowing the heat consumption for heating the cottage, we select a gas boiler for power as follows:
- if you plan to use the unit only for heating, multiply the figure by a safety factor of 1.2;
- the power of a 2-circuit heat generator that provides 2 points of draw-off is better to choose with a margin of 1.3-1.5;
- To work with an indirect heating boiler with a volume of 200-300 liters, you will need a gas single-circuit boiler with one and a half margin of productivity (multiply by a factor of 1.5).
We give an example. For heating a private home with an area of 100 square meters. m calculated requires 9 kW of energy. The minimum power of the gas heater excluding DHW will be 9 x 1.2 = 10.8 kW, a double-circuit boiler - 9 x 1.3 = 11.7 kW. If it is necessary to heat the storage capacity, the performance of the unit increases to 9 x 1.5 = 13.5 kW. Next, we select the closest high power model from the line of heaters - 12 and 15 kW, respectively.
Classification of gas heat generators
All boilers burning natural gas or liquefied propane-butane mixture (LPG) are divided into groups according to the following criteria:
- combustion chamber design - open or sealed (closed);
- mounting method - wall, parapet or floor;
- number of heating circuits - 1 or 2 (heating + DHW);
- energy sources used - only gas fuel or its combination with wood and electricity (the so-called combined boilers).
Note. All varieties of heat generators are initially tuned to burn methane - the main gas. To switch to liquefied fuel, it is enough to replace the fuel jets and adjust the pressure in front of the main burner.
The correct choice of a gas boiler is made according to 3 main criteria - the principle of operation (that is, the type of chamber), the installation option and the ability to additionally heat the right amount of water. Other factors are not so important, but in certain conditions they can play a decisive role:
- heat exchanger design and material - steel, cast iron, copper;
- ignition method - automatic electronic or manual from a piezoelectric element;
- dependence of heater operation on electricity;
- the ability to smoothly or stepwise regulate the power of the gas burner device (modulation);
- etc.
An important nuance. Absolutely all modifications of gas water heaters available on the market are equipped with safety automatics. According to the requirements of regulatory documents, the fuel valve of any boiler must immediately stop supplying fuel in 3 cases:
- If the burner spontaneously extinguishes, for example, due to flame detachment by reverse draft.
- If the gas pressure in the supply line drops below a critical level.
- In the absence of natural draft of the chimney or failure of the fan - blower (as an option - a smoke exhaust) in turbocharged versions of heaters.
Reference. In electronically controlled heat generators, manufacturers provide for additional protection levels - they install temperature sensors, overheat sensors and other automatic safety devices.
The division of gas heating systems into groups cannot be called clear.Example: devices with an open camera can be floor-mounted, wall-mounted and parapet, with some models powered by the mains, others completely independent. We will analyze each group in more detail.
Differences of units according to the principle of operation
Boilers using natural gas as the main energy carrier are divided into 3 categories:
- atmospheric with an open combustion chamber;
- turbocharged (otherwise - inflatable) with a closed firebox;
- condensation - units with a sealed chamber, capable of returning the latent heat of fuel combustion.
We will not consider the pros and cons of each group of heaters, it is better to list the design differences and operational parameters. In the heat sources of the first category, the firebox communicates with ambient air, hence the name - atmospheric. Features of boilers:
- The air necessary for burning fuel is sucked into the chamber due to the natural draft occurring in the chimney. This is a prerequisite for the normal operation of the heat generator.
- The gas burner device of one or two-stage type heats the heat exchanger with a circulating heat carrier with a flame. The exhaust gases independently leave the firebox through the chimney.
- The efficiency of an atmospheric installation rarely reaches 90%, the effectiveness of most such devices lies in the range 86 ... 88%.
- These boilers are considered the cheapest and at the same time reliable in operation. The reason is the minimum of complex electronics or its complete absence.
Explanation. Only units with an open firebox are able to function without electricity. In non-volatile models, an automatic gas valve (most often EuroSIT) deals with the supply of fuel and safe combustion. There is no electronic board and controller; ignition is performed manually with a piezo button.
Turbine heat generators are independent of chimney draft, as air is blown into the closed chamber by an electric fan, whose performance is regulated by the controller. The air is sucked in and the exhaust gases are released through the “pipe in pipe” coaxial chimney laid out along the shortest path, as shown in the photo.
Typically, a double-walled duct is placed horizontally with a slight slope towards the street to drain condensate.
Features and characteristics of pressurized boilers:
- The furnace is not connected with the air environment of the room, the ignition and the combustion process are completely controlled by electronics.
- Units are equipped with two-stage burners or modulation devices with a smooth change in performance.
- The efficiency of various turbocharged devices lies in the range of 90 ... 93% - a higher indicator than that of the "aspirated".
- Boilers need external power from the house electrical network.
Compared to atmospheric "brothers", gas heat sources with a closed chamber are more economical and well automated. The disadvantage is that it is completely dependent on external energy supply, they cut off the light - heating also “died”. To secure the gas turbo boiler, you need an uninterruptible power supply unit or an electric generator.
Reference. At a price, supercharged heaters occupy a middle position between inexpensive "aspirated" and condensing units.
The condensing heat generator device resembles a turbocharged model - the same closed chamber, a fan - an air blower (or smoke exhaust), a double-walled chimney. The device is distinguished by the design of the furnace and a cylindrical burner placed inside the heat exchanger - a stainless steel coil.
How does the boiler work:
- The products of fuel combustion are carbon dioxide and water. The latter evaporates from the flame of the burner and in a conventional heater flies with the smoke into the pipe, taking away part of the heat.
- In the condensation unit, flue gases pass through a coil with a coolant, which is why water vapor condenses on the tubes.The lost heat is returned and sent to the heating of the house. The efficiency of the installation is 95%.
- The water received from the fuel flows down the channel into the condensate collector, and then is discharged into the sewer.
In addition to the dependence on electricity, the described boilers have 2 more minuses - too high a price and a decrease in efficiency in certain operating modes. The essence of the problem will be revealed by our expert in the video:
Wall, stationary and parapet models
As you might guess, the boilers of the first group are hung on the wall, the second - are placed on the floor. Parapet heaters are closer in design to the floor, only fasten to the wall at a level of 70-100 cm.
Installation method - not the only difference between heating units:
- All wall modifications are a miniature gas boiler room. Inside any outboard boiler there is its own circulation pump, safety group, control unit and expansion tank (except for individual instances). Therefore, the wall-mounted device always depends on the reliability of power supply.
- Pendant heat exchangers are made of copper or steel, cast iron is not used. The equipment is offered in 3 versions to choose from - turbocharged, atmospheric and condensing.
- Floor boilers are equipped with steel and cast iron heat exchangers. In Russia and the CIS countries, affordable non-volatile devices of the AOGV type are produced, among imported there are models with external power supply.
- 90% of stationary boilers are equipped with an open chamber and connected to a conventional chimney. There are also supercharged and condensing modifications of units (as a rule, foreign production).
- Parapet heaters are offered only in atmospheric non-volatile design. The maximum power of the gas wall-mounted boiler is small - up to 15 kW, efficiency - 86%. The heat exchanger is “black” steel.
Note. The difference between the three boiler layouts, as well as the advantages and disadvantages of each option are described separately in a detailed review.
From the point of view of the average user, the material of the heat exchanger does not play a big role. Copper radiators are effective, but expensive, cast iron is durable, but too heavy and fragile (afraid of sudden changes in temperature). Stainless steel and “black” steel - a compromise option, implemented by manufacturers in various boilers, regardless of layout.
Varieties of double-circuit water heaters
The main difference between these boilers from single-circuit versions is the ability to provide hot water to the home. Water is heated by the main burner in 4 different ways:
- Using a copper bithermic heat exchanger - a radiator of the "tube inside the channel" type. Water for domestic hot water moves through the internal pipes of the device, and the coolant of the heating system moves through the external channels. The burner heats the outer water jacket, transferring heat to the inner tubes.
- By means of a secondary stainless steel plate heat exchanger. When a request for hot water is received from the mixer, a flow sensor and a three-way valve are activated, directing the entire coolant in a small circulation circle through a secondary heat exchanger. While the DHW circuit is operating, the main heating line with batteries and warm water floors does not heat up.
- An indirect heating boiler with a capacity of up to 100 liters is installed inside the boiler. Its loading is organized according to a similar principle - a three-way valve automatically switches the coolant flow to the tank coil when the water temperature drops below a predetermined level.
- In the cast-iron heat exchanger of the heater, a DHW copper coil is placed.
Bithermal and plate heat exchangers are installed on double-circuit boilers for wall mounting, rarely used in floor versions. Only stationary units are equipped with storage boilers (with rare exceptions).Conventional copper tube coils are used in non-volatile heaters - parapet and floor.
Security Features and Other Utilities
Boilers that do not require a connection to the home electrical network are equipped with mechanical gas automation that meets the minimum safety requirements and turns off the fuel supply in the event of an emergency (listed above). What is important: after the mechanical valve of the EuroSIT type is activated, the user starts the restart manually.
In heaters with automatic ignition and electronic control, the system works differently:
- In any emergency (the gas was turned off, the draft was lost, the flame went out), the valve shuts off the fuel.
- After a few seconds, the controller instructs the valve to open the gas, and the ignition module - to send a spark to the electrodes. That is, the boiler seeks to start on its own, the maximum number of attempts is 4.
- If after 3-4 ignitions the accident repeats, the unit goes into error - turns on the red indicator or shows the code on the display. Further, the intervention of the homeowner or service master is required.
We list other useful functions of modern boilers:
- shutdown in the event of loss of coolant pressure in a closed heating system to 0.3-0.5 Bar (measured by a hydraulic sensor);
- thermostats for overheating water in both circuits (heating and domestic hot water) also turn off the boiler burner;
- built-in three-way valve and additional nozzles for connecting an external indirect boiler;
- the ability to connect a room thermostat, an external weather sensor and a remote control;
- defrost protection - the temperature sensor will start the boiler in the event of coolant cooling to a critical threshold of +5 ° C;
- fitting with valve for feeding the system;
- modulation of the flame of a gas burner device - automatic stepless control of the intensity of combustion depending on the temperature of the supply water.
Electronic control units are able to diagnose problems and give the appropriate signal. If the malfunction threatens safety, the red light on the boiler lights up and the burner turns off; in other cases, the yellow indicator lights up instead of the green one. On models equipped with a display, the error code shown in the instruction manual is displayed.
In conclusion - tips for choosing a domestic boiler
So, you have determined the power of the heat source, place the mod installation and figured out the existing types of gas heaters. It remains to choose the best option.
Recommendation one. According to our experts, the best solution for all occasions is a wall-mounted turbo boiler with a coaxial gas duct. At the cost of equipment, along with installation, the apparatus will be cheaper than buying an “aspirated” and building a full-fledged chimney. One condition: no problems with power supply.
Now we will figure out which gas boiler should be selected depending on the budget and operating conditions:
- Under the gravity (gravity) water heating system, you need to definitely take a non-volatile version of the heater - floor or parapet. The latter is suitable for a small country house with an area of 80 ... 120 m².
- For a closed-type system (the wiring diagram does not matter), any heater from the above is suitable. But it is better to take the wall-mounted version - the product is easier and cheaper to connect, you do not have to buy a safety valve, pump and expansion tank.
- Typical conditions: a smoke channel has already been built, the building has a separate furnace room, the budget is limited. Solution: atmospheric wall-mounted mini-boiler with a minimum set of functions.
- It is also better to put a turbocharged suspended model in the apartment of a multi-storey building, since the removal of combustion products into the ventilation ducts is strictly prohibited.Make a hole in the outer wall and lay a horizontal chimney outside, observing the indentation from the windows.
- A properly selected dual-circuit heater in power will serve a maximum of 2 draw points. Products with plate and bithermic heat exchangers are meant, outdated copper coils are inefficient.
- If the estimated consumption of domestic water is large, you need to purchase a gas column or boiler plus a storage boiler. Do not want to bother with the harness - take the floor-mounted Protherm Bear-KLZ series unit with a built-in capacity of 90 liters.
- Floor models should be purchased in an extreme case, when you can’t choose the wall ones - you need a lot of power, independence from electricity and the like. Stationary gas boilers are more expensive and require additional piping.
Reference. If you are interested in the question which boiler is best to choose, we recommend that you visit a separate page of our resource - a rating of popular models, compiled from the reviews of homeowners on the forums.
Finally, about condensing heating equipment. Now these units are not cheap, the price is not comparable with the increase in efficiency (95% versus 93% for turbocharged devices). The second negative point: the more complex the boiler installation, the more expensive its maintenance and repair. Although it must be recognized that a condensing gas boiler is the best solution for low-temperature heating systems - underfloor heating.