How to calculate the volume of heating: radiators, pipes, expansion tank and other system components

Any heating system has a number of important characteristics - rated thermal power, fuel consumption and volume of components. Calculating the latter indicator requires a careful and comprehensive approach. How to make the correct calculation of volumes for heating: water, tanks, coolant and other system components?

Needs a hundred heating calculations

First, you should decide on the relevance of calculating the volume of water in the heating system or the same indicator for batteries and an expansion tank. After all, you can install these components without complicated operations, guided only by personal experience and professional advice.

The operation of any heating system is associated with a constant change in the indicators of the coolant - the temperature and pressure in the pipes. Therefore, the calculation of heating by the volume of the building will allow you to correctly complete the heat supply, based on the characteristics of the house. In addition, one should take into account the direct dependence of the efficiency of work on the current ferry meters. Since you can calculate the volume of water in the heating system yourself, this procedure is recommended to be performed in order to avoid the following situations:

• Incorrect actual thermal mode of operation, which does not correspond to the calculated one;
• Uneven distribution of heat over heating devices;
• Emergency situations. After all, how to calculate the volume of an expansion tank for heating, if the total capacity of pipelines and batteries is not known.

To minimize the occurrence of these situations, the volume of the heating system and its components should be calculated in a timely manner.

Calculations of heat supply parameters are performed even before installation work. They serve as the basis for the selection of components.

Calculation of the volume of the coolant in pipes and boiler

The starting point for calculating the technical characteristics of the components is the calculation of the volume of water in the heating system. In fact, it is the sum of the capacity of all elements, from the boiler heat exchanger to the batteries.

How to calculate the volume of the heating system yourself, without the involvement of specialists or the use of special programs? To do this, you need a layout of the components and their overall characteristics. The total capacity of the system will be determined by these parameters.

The volume of water in the pipeline

A significant part of the water is located in pipelines. They occupy a large part in the heat supply scheme. How to calculate the volume of the coolant in the heating system, and what characteristics of the pipes do you need to know for this? The most important of these is the diameter of the line. It is he who will determine the capacity of the water in the pipes. To calculate, it is enough to take data from the table.

Pipes of various diameters can be used in the heating system. This is especially true for collector circuits. Therefore, the volume of water in the heating system is calculated using the following formula:

Vtot = Vtr1 * Ltr1 + Vtr2 * Ltr2 + Vtr2 * Ltr2 ...

Where Vtot - total water capacity in pipelines, l,Vtr - the volume of the coolant in 1 lm. pipes of a certain diameter,Ltr - the total length of the line with a given section.

Together, these data will allow you to calculate most of the volume of the heating system. But besides pipes, there are other components of heat supply.

For plastic pipes, the diameter is calculated according to the dimensions of the outer walls, and for metal pipes - according to the inner ones. This can be significant for long-distance thermal systems.

Calculation of the volume of the heating boiler

The correct volume of the heating boiler can only be found from the data of the technical passport. Each model of this heater has its own unique characteristics, which are often not repeated.

The floor standing boiler can be large. This is especially true for solid fuel models. In fact, the coolant does not occupy the entire volume of the heating boiler, but only a small part of it. All liquid is located in a heat exchanger - a structure required to transfer thermal energy from the fuel combustion zone to water.

If the instruction from the heating equipment has been lost, the approximate capacity of the heat exchanger can be taken for miscalculations. It depends on the power and boiler model:

• Floor standing models can hold from 10 to 25 liters of water. On average, a 24 kW solid fuel boiler contains about 20 liters in a heat exchanger. coolant;
• Wall-mounted gas ones are less capacious - from 3 to 7 liters.

Taking into account the parameters for calculating the volume of the coolant in the heating system, the capacity of the boiler heat exchanger can be neglected. This indicator varies from 1% to 3% of the total heat supply of a private house.

Without periodic cleaning of the heating, the cross-section of pipes and the bore diameter of the batteries are reduced. This affects the actual capacity of the heating system.

Calculation of the volume of the expansion tank for heating

For the safe operation of the heating system, it is necessary to install special equipment - an air vent, a drain valve and an expansion tank. The latter is designed to compensate for the thermal expansion of hot water and reduce the critical pressure to normal values.

Closed tank

The actual volume of the expansion vessel for the heating system is not constant. This is due to its design. For closed heat supply circuits, membrane models are installed, divided into two chambers. One of them is filled with air with a certain pressure indicator. It should be less than critical for the heating system by 10% -15%. The second part is filled with water from a branch pipe connected to the mains.

To calculate the volume of the expansion tank in the heating system, you need to find out its filling factor (Kzap). This value can be taken from the data in the table:

In addition to this indicator, it will be necessary to determine additional:

• The normalized coefficient of thermal expansion of water at a temperature of + 85 ° C, E - 0.034;
• The total volume of water in the heating system, C;
• Initial (Rmin) and maximum (Rmax) pressure in pipes.

Further calculations of the volume of the expansion tank for the heating system are performed according to the formula:

If antifreeze or other non-freezing liquid is used in the heat supply, the value of the expansion coefficient will be 10-15% higher. According to this method, the capacity of the expansion tank in the heating system can be calculated with great accuracy.

The expansion tank volume cannot be included in the total heat supply. These are dependent values ​​that are calculated in a strict order - first the heating, and only then the expansion tank.

Open expansion tank

To calculate the volume of an open expansion tank in a heating system, you can use a less time-consuming technique. Less requirements are imposed on it, since in fact it is necessary to control the level of the coolant.

The main factor is the thermal expansion of water as its heating rate increases. This indicator is 0.3% for every + 10 ° С. Knowing the total volume of the heating system and the thermal mode of operation, you can calculate the maximum volume of the tank. It should be remembered that it can only be 2/3 filled with coolant. Suppose that the capacity of pipes and radiators is 450 liters, and the maximum temperature is + 90 ° C. Then the recommended volume of the expansion tank is calculated using the following formula:

Vtank = 450 * (0.003 * 9) / 2/3 = 18 liters.

It is recommended to increase the obtained result by 10-15%. This is due to possible changes in the total calculation of the volume of water in the heating system when installing additional batteries and radiators.

If an open expansion tank performs the functions of monitoring the coolant level, its maximum filling level is determined by the installed additional side branch pipe.

Calculation of the volume of radiators and heating batteries

To perform an accurate calculation, you need to know the volume of water in the heating radiator. This indicator directly depends on the design of the component, as well as its geometric parameters.

As well as when calculating the volume of a heating boiler, the liquid does not fill the entire volume of the radiator or battery. For this, the structure has special channels through which the coolant flows. The correct calculation of the volume of water in the heating radiator can be performed only after obtaining the following device parameters:

• Center-to-center distance between direct and return pipelines to the battery. It can be 300, 350 or 500 mm;
• Manufacturing material. In cast iron models, the hot water filling is much higher than in bimetallic or aluminum;
• The number of sections in the battery.

It is best to find out the exact volume of water in the heating radiator from the technical data sheet. But if this is not possible, you can take into account the approximate values. The greater the center-to-center distance of the battery, the larger the volume of the coolant will fit in it.

To calculate the total volume of water in a heating system with metal panel radiators, you should find out their type. Their capacity depends on the number of heating planes - from 1 to 2:

• For 1 type of battery, for every 10 cm, there is 0.25 of the volume of the coolant;
• For type 2, this figure increases to 0.5 liters per 10 cm.

The result obtained must be multiplied by the number of sections or the total length of the radiator (metal).

For the correct calculation of the volume of a heating system with non-standard design radiators, the above method cannot be used. Their volume can only be found out from the manufacturer or his official representative.

Calculation of the volume of the heat accumulator

In some heating systems, auxiliary elements are installed, which can also be partially filled with coolant. The most capacious of them is the heat accumulator.

The problem in calculating the total volume of water in the heating system with this component is the configuration of the heat exchanger. In fact, the heat accumulator is not filled with hot water from the system - it is used to heat it from the liquid in it. For a correct calculation, you need to know the design of the internal pipeline. Alas, manufacturers do not always indicate that parameter. Therefore, you can use an approximate calculation methodology.

Before installing the heat accumulator, its internal pipeline is filled with water. Its amount is calculated independently and taken into account when calculating the total heating volume.

If the heating system is being modernized, new radiators or pipes are installed, an additional recalculation of its total volume must be performed.To do this, you can take the characteristics of new devices and calculate their capacity using the methods described above.

As an example, you can familiarize yourself with the method for calculating the expansion tank: