The power of a gas boiler is an important parameter on which the comfort of living in the rooms heated by it depends. To choose the best option for a house or apartment, you need to consider their size. The required performance of heating equipment depends on the area of the heated rooms and some other, less significant factors.
What affects the rated power
The boiler must not only make up for all the heat losses of a particular building or premises, but also have a certain power reserve. Why is it necessary to take a value greater than the calculated:
- equipment should not work to the limit - this leads to premature wear;
- the probability of abnormal temperatures must be taken into account;
- for a private house it is useful to consider the possibility of expanding the area.
Some buyers do not know in which units the main parameter of gas equipment that determines its performance is calculated. The heat output of the apparatus is measured in kilowatts (kW). This value is always indicated in the technical passport of each model.
What affects heat loss
To find out what equipment performance is needed, in addition to the area, you need to take into account other factors:
- climate in a specific region;
- volume of a residential building / apartment;
- degree of insulation;
- probable heat loss.
When using turbocharged devices, it is also necessary to take into account the amount of energy spent on heating the air.
To determine the performance of the boiler, you must first calculate the heat loss. The heat engineering calculation is characterized by increased complexity, since it takes into account a huge number of components:
- materials from which walls, ceilings, roofing, etc .;
- type of wiring of the heating system;
- the presence of the "warm floor" system;
- household appliances that produce heat.
Professionals use thermal imagers, and then perform calculations using complex formulas. It is clear that the average user does not have to understand the nuances of heat engineering - there are available methods for them that allow you to quickly and accurately determine the optimal heat output of the equipment.
What are the calculation options
To make the right choice of gas equipment, we suggest using three calculation options:
- Precise heat engineering - not suitable for ordinary consumers, complex and requires the use of a thermal imager.
- On the online calculator - to get the result, the user enters the initial data into a special program: the number of windows, doors, wall thickness and other information. Based on them, the program produces a result.
- Manual calculations. The most affordable way to find out the optimal heat output of a heater is to use the elementary ratio of area and power. The formula used is: 10 m² = 1,000 watts. Such a simple option is correct for structures characterized by an average degree of thermal insulation and having ceilings about 2.7 m high.
Developers, calculating the power characteristics of heating devices, often take into account the volume of the premises. In the technical documentation of imported models, the parameter “heating in m³” is often found.
Calculation of boiler power with one circuit
Having performed the simplest calculation for a single-circuit wall or floor boiler using the ratio: 10 kW per 100 m², it is necessary to increase the calculated value by 15–20%.
We give an example of calculations. It is necessary to equip a house of 80 m². To heat it, you will need a device for 9 600 W = 8 000 W + 20%. If there is no exactly suitable option for sale, you should take a modification with greater performance. This method of calculation is suitable only for devices with a single circuit, without an indirect heating boiler.
Calculation of boiler power with two circuits
The calculation is based on the following ratio: 10 m² = 1,000 W + 20% (supply) + 20% (water heating). If the house has an area of 200 m², then the desired value will be: 20,000 watts + 40% = 28,000 watts.
Determining the power of a model with a boiler
First, the required volume of the boiler is determined so that it can meet the household needs for hot water. Water consumption is calculated taking into account the operation of all points of water intake:
- bathtub - 8–9 l / min;
- shower - 9 l / min;
- toilet - 4 l / min;
- sink - 4 l / min.
The technical documentation for the boiler indicates what kind of boiler capacity is required in order to provide water heating. A heater with a capacity of about 30 kW is suitable for a 200 liter water boiler. Then calculate the performance required for heating. The results are summarized. At the end of the calculations, it is necessary to subtract 20% from the result obtained, since water heating for domestic hot water and heating occurs simultaneously.
Calculation of boiler capacity for typical houses, taking into account the climatic zone
For houses built according to standard designs, the formula is used: M = S * UM / 10, where
- M / UM - calculated / specific power, kW;
- S - area, m².
UM depends on the region, kW:
- south - 0.7–0.9;
- the average band is 1.0–1.2;
- Moscow Region - 1.2–1.5;
- North - 1.5–2.0.
We will perform calculations for a house with an area of 300 m² located in the Moscow Region: 300 * 1.3 / 10 = 39 kW. This result is suitable for installing single-circuit models. In order to calculate the power of the dual-circuit apparatus, it is necessary to increase the total number by 25%.
Is excess power needed
You should not buy a model with a performance significantly exceeding the maximum indicator (taking into account a premium of 15-20%). Excess leads to negative consequences:
- High price. The more powerful the model, the more expensive it is. It is irrational to acquire equipment whose capabilities will not be used.
- Increased costs for consumables.
- Low efficiency of the burner - this will affect the gas flow.
- At minimum loads, automation more often breaks down.
- If the equipment is not optimal for a specific area, there is an accelerated wear of components and parts.
How to calculate expenses
Knowing the power characteristics of the equipment, you can calculate the gas flow. When calculating the efficiency is taken into account. Standard versions have an efficiency of 92–93%, condensation type models - 108–109%. With 100 percent heat transfer, 10 kW of thermal energy is generated after the combustion of 1 m³ of natural gas. Thus, to create a power of 10 kW with an efficiency of 92%, the fuel consumption will be 1.12 m³, and with an efficiency of 108% - 0.92 m³.
When calculating the amount of fuel consumed, take into account the performance of the devices. A 10 kW model burns 1.12 m³ of gas in an hour, and 4.48 m³ for 40 kW. Manufacturers often indicate in the technical documentation the average value of fuel consumption, but still it is different for each model.
To know the upcoming heating costs when using volatile versions, you also need to calculate the cost of electricity.
How to take into account the height of the ceilings
The above calculation formulas are suitable for buildings whose ceiling height does not exceed 3 meters. If the ceilings are higher, you need to use other formulas: M = Q * K, where:
- M - rated power, kW;
- Q - heat loss, kW;
- K is the safety factor.
K = 1.15–2, or 15–20%.
To calculate the heat loss, use the formula:
Q = V * P * k / 860, where:
- V - volume of premises, m³;
- P is the difference between the temperatures in the house and on the street, ° C;
- k is the dispersion coefficient, depending on the thermal insulation characteristics of the structure.
The value of the coefficient is determined by the type of structure:
- not having thermal insulation: wooden structures, structures from corrugated iron sheets, - 3.0-4.0;
- with low thermal insulation - 2.0-2.9;
- with average thermal insulation - 1-1.9;
- with high thermal insulation - 0.6-0.9.
If the structure is small and has good thermal insulation characteristics, a large boiler output is not required. It happens that there is no option with suitable characteristics for sale. Then you need to take the option with a heating capacity slightly higher than the calculated value. The difference will be smoothed out by automatic regulation systems.
Online calculator
The most advanced manufacturers thought about the comfort of consumers, placing online calculators on their websites, which make it easy and quick to find out the necessary performance of gas equipment. To calculate the following information:
- temperature that the consumer wants to have in the house;
- average outside temperature during the coldest week;
- availability of hot water supply;
- number of storeys;
- ceiling height;
- floor material;
- wall thickness and materials from which they were erected;
- wall length;
- number of window openings;
- window features - design details;
- window dimensions.
By filling in the fields, you can quickly calculate the calculated value of the heat output.
Wall or floor boilers choose
The choice of the type of installation of the heater depends not only on the preferences of the consumer, but also on the calculated heat output.
Wall-mounted boilers, unlike floor-mounted boilers, have a lower power range. They are compact, they can be placed in the kitchen, attic, in the basement.
Floor models are more bulky, they are usually installed in separate rooms. The wall-mounted versions are represented by a power range of 12–36 kW; the performance of floor models can reach 160 kW.
The functionality of wall and floor versions does not differ much. Modern devices of both types require manual or automatic control.
Wall-mounted models are usually bought in apartments - they are compact and easily fit into the interior of the kitchen. For heating large houses and cottages, more powerful floor heaters are used. Atmospheric versions are installed in separate, well-ventilated rooms. To the rooms in which the turbocharged devices are mounted, the requirements are much lower.
What else affects the choice
In addition to heat production, you need to consider:
- number of circuits (only heating or heating and domestic hot water are needed);
- installation method (wall or floor);
- combustion chamber (open or closed; in the first case, air is taken from the room, in the second - from the street through a coaxial chimney);
- design - for consumers, appearance is not the last thing. Modern devices are not only functional, efficient, safe, but also beautiful.
The right choice of thermal performance of a gas boiler will allow you to use the equipment with maximum efficiency. An optimally selected model will not only provide a comfortable temperature in the house, but will also serve with minimal wear on parts and assemblies.