How to calculate the capacity of heating batteries for a private house

Maintaining an efficient home heating system is essential for creating a comfortable living space, particularly in the winter. Radiators, sometimes referred to as heating batteries, are an essential part of any private home’s heating system. The purpose of these devices is to distribute heat throughout the house; however, it can be difficult to determine the appropriate capacity for them.

The capacity of heating batteries must be determined by taking into account a number of particulars that are specific to every house. The size of the house itself is one of the main determinants. More powerful heating systems are usually needed in larger homes in order to properly heat every room. The quality of the insulation, the climate, and the intended interior temperature all have a major impact on the amount of capacity required.

When determining the capacity of a heating battery, insulation is an important factor to take into account. A house with adequate insulation retains heat more efficiently, which lessens the strain on the heating system. On the other hand, a house with inadequate insulation will need a higher heating capacity to offset heat loss via the walls, windows, and roof.

Accurate capacity calculations depend on knowing the unique heating requirements of each room. Large windows and high ceilings can cause a room to lose heat more quickly, necessitating the need for more heating capacity. However, less heating capacity might be needed in rooms that are rarely used or have little exposure to the outside.

Thankfully, homeowners can accurately determine the capacity of heating batteries with the use of formulas and guidelines. Through careful consideration of variables like house size, insulation quality, and room-specific needs, homeowners can guarantee that their heating system performs effectively and efficiently, providing year-round warmth and comfort in their homes.

Input data for calculations

Depending on the quantity of windows, external walls, and street-facing entry doors in each room, the heat output of the batteries is calculated individually. Answer the following three questions in order to determine the heat output of heating radiators:

1. How much heat is needed to heat the living room.
2. What air temperature is planned to maintain in a particular room.
3. Average water temperature in the heating system of an apartment or a private house.

Note: If the cottage has a single-pipe installation, you will need to add sections to the last radiators in order to correct for the coolant’s cooling.

The first question, which asked how to determine the necessary quantity of heat energy in various ways, has an answer that can be found in a different guide that deals with calculating the load on the heating system. Here are two streamlined calculation methods: area and room volume.

Measuring the area that needs to be heated and allocating 100 W of heat per square meter, or 1 kW per 10 m², is a typical method. We suggest improving the procedure by accounting for the quantity of external walls and light openings:

• for rooms with 1 window or entrance door and one external wall, leave 100 W of heat per meter square;
• Corner room (2 exterior fences) with 1 window opening – count 120 W/m²;
• same, 2 light openings – 130 W/m².

Important condition. The building is situated in the middle of a temperate climate zone, and the calculation yields results that are roughly accurate for ceiling heights up to three meters. A coefficient of one that increases is used for the northern regions. 5…2.0, southern – 0.7-0.8 reduction.

In cases where the ceiling height exceeds three meters, such as a hallway featuring a staircase in a two-story home, it is more accurate to determine the heat consumption using the following formula:

• room with 1 window (external door) and only one external wall – 35 W/m³;
• the room is surrounded by other rooms, has no windows, or is on the sunny side – 35 W/m³;
• corner room with 1 window opening – 40 W/m³;
• the same with two windows – 45 W/m³.

The second question is simpler to respond to: 20–23 °C is a comfortable range for living temperatures. More heating of the air is not cost-effective; colder is weaker. For computations, the average value is plus 22 degrees.

Heating the heat carrier to between 60 and 70 degrees Celsius is the ideal boiler operation mode. Days that are excessively warm or cold are the exception, in which case the water’s temperature must be adjusted. Since there aren’t many days like this, the system’s average design temperature of +65 °C is assumed.

Passport and real heat output of the radiator

The technical passport lists the heater’s parameters. Manufacturers typically state that a single standard section with an interaxial size of 500 mm can have a power output of 170–200 watts. Radiators made of aluminum and bimetallic materials share many characteristics.

The trick is that you cannot arbitrarily choose how many sections to include by using the heat transfer passport index. As per GOST 31311-2005, p. 3.5, the manufacturer is required to specify the battery capacity for the following operating circumstances:

• the heat carrier moves through the radiator from top to bottom (diagonal or lateral connection);
• the temperature head is 70 degrees;
• the water flow rate through the device is equal to 360 kg/hour.

Citation. The heat head is the difference in temperature between the room air and the mains water on average. DT, dt, or ΔT is computed using the following formula:

To clarify the essence of the issue, let’s perform the calculation in reverse and enter the known values of ΔT = 70 °C and room temperature – plus 20 °C into the formula:

1. t supply + t return = (ΔT + t air) x 2 = (70 + 20) x 2 = 180 °C.
2. According to the norms, the calculated temperature difference between the supply and return line should be 20 degrees Celsius. So, the water coming from the boiler must be heated to 100 °C, the return water will cool down to 80 °C.
3. The 100/80 °C operating mode is not available for domestic heating systems, the maximum heating is 80 degrees Celsius. In addition, it is not economically favorable to maintain the specified temperature of the heating medium (remember, we took an average of 65 °C).

In conclusion. The battery will produce a lot less heat in actual use than what the operating instructions claim. The temperature difference between water and surrounding air is the reason for the lower value of ΔT. Based on our preliminary data, ΔT is approximately twice lower than the stated norm, or 130 / 2 – 22 = 43 degrees.

Determine the number of sections of the aluminum battery

Recalculating the heater’s parameters for a given set of circumstances is difficult. For average homeowners who are unfamiliar with heat engineering, the design engineers’ heat capacity formula and calculation algorithm is too complex.

We suggest using a more accessible method to calculate the number of radiator sections for heating, with the least amount of error possible:

1. Gather the initial data listed in the first section of this publication – find out the amount of heat required for heating, the air temperature and the temperature of the heating medium.
2. Calculate the real temperature head DT using the above formula.
3. When choosing a particular type of radiator, open the data sheet and find the heat transfer rate of 1 section at DT = 70 degrees Celsius.
4. Below is a table of ready-to-use conversion factors for the heating capacity of radiator sections. Find the value corresponding to the real DT and multiply it by the value of the passport heat transfer – get the power of 1 fin under your operating conditions.

Determining the actual heat flux makes determining the number of battery fins needed to heat the room easy. The required heat must be divided by the output of one section. Here’s an illustration of the calculation for your reference:

1. Take a corner room with two translucent structures (windows) with an area of 15.75 m², ceiling height – 280 cm (shown in the fragment of the drawing). The specific heat input for heating is 130 W/m², the total demand will be 130 x 15.75 = 2048 W.
2. We found out the value of the heat head in the previous section, DT = 43 °C.
3. Selecting low aluminum radiators GLOBAL VOX 350 (center distance – 350 mm). According to the product documentation, the heat output of 1 fin is 145 W (DT = 70 °C).
4. Find in the table the coefficient corresponding to DT = 43 °C, K = 0.53.
5. Multiply the nameplate power by the coefficient and find the real output of 1 section: 0.53 х 145 = 76.85 W.
6. Calculate the number of aluminum fins per room: 2048 / 76.85 ≈ 26.65, we round up and get 27 aluminum fins.

The sections still need to be distributed throughout the space. We split 28 windows in half if their sizes are the same, and we position a radiator with 14 ribs beneath each aperture. If not, the radiator’s section count is chosen proportionately to the window width (approximation is possible). Recalculating the heat output of cast iron and bimetallic radiators is done in a similar manner.

Advice: If you have a personal computer, using the Italian brand GLOBAL’s calculation program, which is available on the manufacturer’s official website, is simpler.

The heat output of many well-known companies’ devices (such as GLOBAL) is specified in the documentation for various temperature conditions (DT = 60 °C, DT = 50 °C); the table below provides an example. Feel free to use the given characteristics without recalculating if your real ΔT = 50 degrees.

Calculation of steel radiator size

Panel devices are not designed like sectional devices. Pressed steel sheets, pre-cut to the appropriate size, ranging in thickness from 1.2 to 1.2 mm, are used to make the radiators. The heat output of a panel that has been welded from sheets that is one meter in length must be determined in order to select a radiator with the necessary capacity.

Our proposal is to employ a straightforward methodology grounded in technical data provided by Kermi, a reputable German manufacturer of panel water radiators. The point is that while stamped batteries are all the same, the number of heating panels and heat exchange fins makes each product type unique. Radiators are categorized as follows:

• type 10 – single panel device without additional ribs;
• type 11 – 1 panel + 1 sheet of corrugated metal;
• Type 12 – two panels plus 1 fin sheet;
• type 20 – battery for 2 heating plates, convection ribbing is not provided;
• type 22 – two-panel radiator with 2 sheets that increase the heat exchange area.

Note: Although type 33 heaters (three panels plus three ribs) are also available, their higher cost and thickness make them less popular. Type 22 is the most "popular" model.

Thus, the only difference between panel stamped devices of any brand is their mounting size. The only real work involved in calculating heating radiators is to choose the right kind. The height and heat output are then used to determine how long the battery will last in a given room. The following is the algorithm:

1. Determine the initial data listed at the beginning of the article.
2. Select the type and height of the heater. The most common options – products with height of 30, 40 and 50 cm, type 22.
3. Use the table provided, where the heat output q (W/1 m) is indicated. п.) Kermi radiators of different types and sizes depending on the operating conditions. Start from the left column – find the corresponding room temperature, then – the heat carrier, then the height and type of radiator. In the cell at the intersection of the row and column find the power of 1 meter of radiator.
4. The amount of energy required for heating, divide by the value q – you will find out the meterage of the radiator of a given height.
5. According to the catalog, select a water heating device of the appropriate length. If necessary (e.g. the battery is too long), split this size into 2-3 units.

Example of a calculation. Let us calculate the following parameters for a steel radiator in the same 15.75 m² room: coolant temperature of 65 °C, air temperature of 22 °C, and heat loss of 2048 W. Let’s use type 22 standard radiators that have a 500 mm height. Determine the total length of the panel (2048 / 1461 = 1.4 м) using the table’s value of q = 1461 W. Select the closest larger option (heater length 1.5 m or 2 units of 0.7 м) from any manufacturer’s catalog.

Tip: For Kermi products, our instruction is 100% accurate. When purchasing radiators from a different brand, particularly Chinese ones, it is advisable to allow 10-15% extra length for the panel.

Heaters in single-pipe systems

A crucial characteristic of the horizontal "leningradka" is the addition of cooled coolant from the radiators, which causes the main line’s temperature to gradually drop. The temperature differential at the start and finish of the distribution pipe can reach up to 15 °C if one ring line services more than five devices. As a result, less heat is released by the final radiators.

When calculating the heating capacity, make the following adjustments to make sure the room receives the appropriate amount of energy from the long-distance radiators:

1. Select the first 4 radiators according to the above instructions.
2. Increase the capacity of the 5th device by 10%.
3. Add another 10 percent to the calculated heat output of each subsequent radiator.

Justification. The sixth radiator gains 20% more power, the seventh gains 30% more power, and so forth. The expert will explain in detail on the video why it is necessary to build up the final batteries of a single-pipe "leningradka":

Selecting the ideal heating system for your home is essential to maintaining both comfort and energy efficiency. The capacity of heating batteries is determined by taking into account a number of factors.

First, think about the size and insulation of your home. Your home’s insulation will help it retain heat longer, which will ease the strain on your heating system. To precisely calculate the amount of heating you will need, figure out the total square footage of your living area.

Then consider the climate in your area. To keep a comfortable temperature inside, milder climates might require less heating power, while colder climates might require more. Take into account the average wintertime temperature as well as the frequency of very cold spells.

Additionally, consider the unique heating requirements of every room in your home. Higher ceilings or more windows may need to be added to a room’s heating capacity in order to offset heat loss. To guarantee even heating throughout your house, figure out how much heat escapes from each room separately.

Finally, don’t forget to take your heating system’s efficiency into account. In the long run, you can reduce your heating costs by using more energy-efficient modern radiators that can produce more heat with less energy. To get the most comfort and savings, go for heating batteries with a high energy efficiency rating.

You can minimize energy waste and save money on heating costs by carefully weighing these factors and determining the capacity of your heating batteries accordingly. This will help you keep your private house warm and comfortable throughout the winter.

In figuring out how to size your heating radiators for a private home, several key factors come into play. First off, you"ll need to calculate the heat loss of each room, considering aspects like insulation quality, window size, and external temperature. Then, determine the required heat output for each room based on its size and purpose. With these figures in hand, you can select radiators with the appropriate heat output to effectively warm each space. It"s crucial to strike a balance between adequate heating capacity and energy efficiency, ensuring comfort without unnecessary expense. Consulting with a heating professional can help navigate the complexities of sizing heating radiators for your specific home setup, ensuring optimal warmth and cost-effectiveness.

Video on the topic

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