Country house heating options: boiler selection

Country house heating options: boiler selection

The increase in energy prices leads to a stable increase in utility tariffs. The wear of boiler equipment and dilapidated mains reduce the reliability of centralized heat supply. There are autonomous options for heating a country house: the right choice of boiler will reduce dependence on external factors, increase the efficiency and functionality of the system. Foreign and domestic manufacturers produce heat generators for private homes. Generators run on electricity, solid, liquid and gaseous fuels. Each type of energy resource has its own advantages and disadvantages, but the choice of boiler depends on the available fuel.

The right choice of boiler for a frequent home will increase the efficiency and functionality of the heating system

Country house heating options: how to choose a boiler

How to choose a boiler for heating a private house? Individual construction presupposes the existence of a project, which includes a thermal calculation of the building. Schemes, details and recommendations of designers on the arrangement of the heating system make up the engineering part of the document. If there is no ready-made solution, then the article offers the reader the principle of self-selection of boiler equipment.

The power of the generator must correspond to the thermal load of the heated rooms. Deviations lead to uneven heating of heating devices, fuel overspending, overheating of the coolant and equipment breakdown.

When calculating the boiler capacity, it is necessary to take into account the thermal load of the heated rooms

The formula for determining the boiler power:

Wkot = (S x Wud)/10 (kW), where

Wkot — boiler power, kW;
S — heated area, m2;
Wud is the specific power of the climate zone per 10 m2 of room area, kW.

Table 1. The value of specific power by climatic zones:

Important! The simplified method of calculating the power (1 kW per 10 m2 of area) does not take into account the climatic conditions of the terrain, height, materials and the degree of insulation of the house.

When choosing heating equipment, it is necessary to take into account the climatic conditions of the area

The effective operation of autonomous heating is impossible without compliance with a set of measures:

• insulation of ceilings, floors, exterior walls, roofs, basements, attics, installation of double-glazed windows and modern door blocks;
• preliminary heat engineering calculation (determination of heat loss through enclosing structures);
• compatibility of heating system equipment — design recommendations;
• high-quality installation of the system, compliance with the rules of commissioning and operation of equipment;
• timely prevention — flushing and hydraulic testing of the heating system at the end of the heating period;
• preliminary water treatment — filtration and softening of boiler water.

The efficiency of the heating system will directly depend on the quality of its calculation and installation

Types of water heating systems

The water heating system is simple, reliable and economical: the boiler generates, and the water flow through the secondary circuit transmits thermal energy to the living room. The volume of water in the heating system is conventionally taken as 15 liters per 1 kilowatt of boiler power. The enlarged standards take into account the filling of the boiler and secondary circuits, the capacity of radiators, risers, wiring pipes, heat exchangers, hydraulic separators, distribution combs and heat storage tanks.

The natural transfer of thermal energy occurs according to the laws of gravity. Forced circulation of the coolant makes the process directional, predictable and controllable.

The water heating system is the simplest and most reliable in operation

Heating of houses up to 100 sq. m

Heating of houses of a small area does not require the installation of pumping equipment — the movement of the coolant occurs naturally. The liquid, passing through the heat exchanger of the boiler, heats up. The density of the medium decreases, and the volume increases and pushes the flow from the boiler into the main riser. The heated water rises up, enters the distribution line, then into the heating devices. By transferring heat to the radiator body, the coolant cools down, and its density increases. At the outlet of the heating devices, the cooled water enters the return line and moves in the direction of the boiler.

The supply and collecting pipelines are laid with a slope in the direction of flow (the supply line to the heating devices, the return pipeline to the boiler).

Water underfloor heating is a common method of heating a private country house

Heating of houses over 100 sq. m.

Houses with an area of more than 100 m2 are equipped with a system of forced circulation of the coolant. The power of the boiler and pump depends on the thermal load of the room, the total heat loss, the number of heating circuits and appliances. Traditionally, the pumps are installed on the bypass of the return line, along which the cooled coolant returns to the boiler. Additionally, pressure is pumped into the long-range hot water system and independent low-temperature heating circuits of underfloor heating.

Circulation pumps for heating are chosen as a compatible element of the system, taking into account the nominal capacity and pressure. The operating characteristics of the pump specified in the technical data sheet must correspond to the calculated values.

Structure and device of the circulation pump

Calculation of pump performance:

G ≅ Q/(ΔT x 1,16) (m/s, l/s, m3/h), where

G — circulation pump capacity, m3/h;

Q — maximum boiler capacity, according to the passport data, kW;

ΔT is the temperature difference in the supply and return pipelines of the heating system, °C;

1.16 is the coefficient of specific density of water, Wh/kg℃.

The principle of operation of the circulation pump

Calculation of the circulation pump head:

H ≅ (R x L x Zƒ)/1000 (m), where

H — head of the circulation pump, m;

L is the total length of the supply and return pipelines, m;

R is the maximum resistance value on straight sections (Pa/m, 0.015 pascal per 1 linear meter);

Z is the product of the reserve coefficients by local resistances, Pa: resistance in ball valves, bends and fittings; internal resistance in throttles and thermostatic regulators; resistance in mixers and water taps. If the heating system includes valves, fittings, temperature control valves, faucets, then Z = a x b x c.

Connection diagram of the circulation pump to the heating system

Modern technologies allow you to automatically adjust the rotor speed. The pump reacts independently to peak changes in the operating load. Adapted models of autonomous heating heat generators are equipped with a circulation pump built into the boiler circuit.

Wood-fired stove heating

An eco-friendly and non-volatile version of water heating from a wood-burning stove is successfully used by residents of some regions of Russia. The reasons for the organization of furnace heating of a private house without gas and electricity are the absence or remoteness of a gas pipeline, the high price of connecting communications.

Heating furnaces made of bricks have a large weight, they are installed on a separate foundation. The furnace is laid out with a refractory brick. Inside, a welded coil made of steel with a thickness of 3 ÷ 5 mm is installed, which is connected to the water heating circuit. Sometimes the boiler circuit is built into the masonry array, shielding from the high temperature zone.

In a country house, you can use wood-fired stove heating

The dimensions, shape and position of the heat exchanger must ensure the required heating of the coolant. The coil located in the body of the masonry allows you to get enough heating at the outlet for the operation of the low-temperature contour of underfloor heating (30 ÷ 60 ° C). There are no general recommendations for the device of brick furnaces. Experienced stoves perform work according to their own calculations and drawings, keeping the secrets of craftsmanship in the strictest secrecy. The cost of the services of professional stoves (starting from 40 thousand rubles and above) depends on the region, materials and design of the hearth.

The advantage of stone wood-burning heating stoves: individual project selection and repair, available for independent execution. The array and heat capacity of the material allows you to accumulate thermal energy. The radiation of heat from the surface of the masonry does not stop after the end of gorenje wood, which creates comfortable conditions in the house. Wood-burning stoves are additionally used for cooking, heating water and household needs.

Wood-burning stoves Thermophore with surface for cooking

The lack of water heating from a brick stove on firewood: reducing the speed of the coolant when the stone cools down. The installation of a circulation pump increases the efficiency of heating, but makes the system dependent on electricity supply.

Heating using solid fuel boilers

Factory models of classic wood-burning boilers are classified as solid fuel. Non-volatile equipment is made of cast iron or steel. Durable cast-iron units consist of prefabricated sections, which allows repair and replacement of elements. Steel models withstand sudden changes in pressure and temperature. Disadvantages of classic solid fuel boilers: the need for frequent fuel loads and mechanical cleaning of the furnace, chimney, ash pan.

The best option for heating a country house is a combined boiler (firewood/electricity)

Pyrolysis (gas generator) units are distinguished by the operating time on one tab up to 10 hours, efficiency of 90%, complete combustion of fuel. However, the conditions of stable gorenje depend on the quality of firewood (coal) and the completeness of the loading of the furnace chamber. Adjustment and automation in the pyrolysis process is impossible, therefore, the power of the unit changes in stages, from the beginning, peak and end of gorenje.

The device of solid-fuel boilers of long-term gorenje is fundamentally different from pyrolysis. Constructions with a vertical furnace and a metered air supply increase the burning time.Gorenje

A cross-sectional view of a traditional solid fuel boiler (left) and a solid fuel boiler of long gorenje (right)

The possibility of using any type of solid fuel and switching to an alternative heating method increases the attractiveness of combined models. Modification of the units allows, if necessary, to install gas burners and electric heaters in the furnace. The manufacturer’s recommendations specified in the boiler passport facilitate the installation of the unit, the installation of the chimney and the selection of additional equipment.

Models of combined heating boilers (firewood/ electricity) are in particular demand among buyers. The price of units of the same capacity is presented for comparison in the overview table:

Domestic developments have received consumer recognition in the category quality-price of solid fuel boilers for heating a private house. The reviews that the owners of the equipment leave on independent forums indicate the competitiveness of Russian brands.

Gas heating of a private house

Statistics state that 2/3 of autonomous heating systems are a variant of gas heating of a country house. Cheap fuel justifies the high cost of the units: the gas enters the furnace automatically, constant control over the gorenje process is not needed. Gas heat generators are equipped with a burner, a built-in circulation pump, an expansion tank, a heat exchanger, a safety system and an automation group.
Let’s consider the classification of gas-fueled boilers and give an example of calculating the gas consumption for heating a private house.

Autonomous heating of a country house using gaseous fuel

Gas boiler capacity

The gas boiler is selected according to the power of the unit. The standard condition — 1 kW of boiler power per 10 square meters of area is met if the structural elements of the building are insulated and the ceiling height does not exceed 3 meters. The dilapidation of enclosing structures or the installation of a heat exchanger for hot water is the reason for choosing a heat generator with a margin of performance.

Important! The power of the unit stated in the technical data sheet corresponds to the standard pressure in the supply gas line (0.003 MPa low pressure). In practice, the gas pressure is lower than the contractual values, therefore, the boiler capacity may differ significantly from that indicated in the passport.

When choosing the power of a gas boiler, the norm of 1 kW per 10 sq. m is taken into account

Number of contours

Steel single-circuit heating units with a copper heat exchanger are used for heating small houses. Heating gas generators equipped with automation are used for radiator heating and low-temperature underfloor heating circuit. For hot water supply, the system is supplemented with a boiler and a circulation pump.

Double-circuit gas boilers are used simultaneously for heating and hot water preparation. There are floor models of double-circuit gas boilers made of cast iron, with a built-in storage boiler. The wall version of lightweight structures, with a heating ring and a flowing water heater, is made of steel.

Vaillant gas wall-mounted double-circuit boiler

Combustion chamber type: open and closed

Open fireboxes take air for gorenje gas from the room in which the boiler is installed. The equipment should be located in a special furnace room equipped with supply ventilation and a vertical chimney.

Gas boilers with a closed combustion chamber work due to forced air intake from the street. The associated discharge of gorenje products heats up a portion of fresh air and increases the efficiency of the heat generator.

Gas supply of a private house using a gas boiler and a gas generator

Exhaust system of combustion products

The classic way to remove exhaust gases is natural draft or forced exhaust through the chimney. The modern version is a coaxial hood of the pipe-in-pipe type. A similar exhaust gas removal system does not require the installation of a classic chimney. The combustion products go out through the inner pipe. Fresh oxygen-enriched air is sucked into the gap between the inner and outer shell of the pipe. External weather conditions do not affect the air supply to the combustion chamber and exhaust gas discharge.

Important! Boilers on gas fuel are classified as explosive and fire-hazardous units. The regulations for the installation of the generator are prescribed in the regulatory documents concerning individual boiler installations. Compliance with the rules requires personal safety considerations: with a lack of oxygen, natural gas does not burn completely. The resulting mono carbon monoxide (CO↑) is colorless and odorless. The presence of 1% carbon monoxide in the room air is dangerous for human health and life. Fuel leakage and the formation of an explosive gas-air mixture can lead to sad consequences.

It is better to install an outdoor gas boiler in a separate room

Gas consumption for heating a house of 100 m2

Preliminary calculation of gas consumption is carried out to determine the economic profitability of the generator and the feasibility of using other types of fuel. The estimated gas consumption can be found from the technical passport of the boiler. Manufacturers indicate the hourly resource requirement. The value is multiplied by 720 (the number of hours in a day and days in a month), then divided by 2 (recommended power correction) and multiplied by 7 (average heating period).

According to theory, the economical operation of the heat generator allows you to generate 1 kW of thermal energy when burning 0.1 m3 of gas. So, by burning one cubic meter of gaseous fuel, you can heat a residential building with an area of 100 square meters for one hour. The daily gas consumption is 24 m3.

Related article:

Outdoor gas boilers for home heating. Choosing the optimal model. Advantages and types of gas equipment. Single- and double-circuit units. Boiler power selection. Schemes of heating systems.

The maximum price per cubic meter of gas for the population is 7 rubles 29 kopecks (Russia, Omsk, March 2016). The cost of fuel for heating a residential building with an area of 100 m2 will be 175 rubles per day or 5250 per month. If we take into account that the standard duration of the heating season depends on the climatic zone, and the boiler does not work constantly with the maximum load, then the annual gas bill will not exceed 20,000 rubles.

Daily gas consumption for heating a house with an area of 100 sq. m. m is 24 cubic meters. m

In practice, the gas consumption for autonomous heating is determined by the metering device. The amount of gas bills during the heating season is comparable to the amount of centralized heating of a private house for a month! According to the reviews of owners of autonomous heating systems with a gas boiler, the costs of the project, equipment and installation of the heating system pay off within 3-5 years.

Useful advice! The feedback system (temperature sensors and programmer) of the gas boiler will provide fuel savings of up to 20%.

Table 3. Models of gas boilers for heating a private house (prices):

Electric heating

A simple, fast and, at first glance, inexpensive way to warm up a country house is to install an electric boiler. However, the operating costs significantly exceed all existing heat supply systems.

The main condition for stable operation of electric heating is uninterrupted supply and sufficient power of electrical wiring. It is reasonable to use combined options for electric heating of a country house.

Wiring diagram of an electric boiler in the heating system

The appearance of an electric boiler resembles a classic water-to-water heat exchanger: a cylindrical chamber inside which thermal electric heating elements are located. The generator operates from a household or three-phase network (voltage 220 or 380 V). According to the principle of heating, electrode (tenov) and induction models are distinguished. The efficiency of electric units is 90%. There are models of single and double-circuit electric boilers.

Table 4. Electric boilers for heating a country house (options and prices):

The question of which heating is better for private homes, each owner decides for himself. However, it must be remembered that the economic feasibility of new-fangled trends is questionable, and the repair of high-tech boilers in a remote area is problematic. The best option is a combination of units with different fuels.