Modern heating system is a demonstration of a completely new approach to its regulation. To date, this is not a preliminary adjustment before starting the system with the facilitation of the subsequent hydraulic mode of operation. Modern heating in a private house during operation has a constantly changing thermal regime. Which requires the equipment not only to track changes in space heating, but also to respond to them correctly.
Conditions for efficient operation of the system
There are some points, the observance of which will ensure the high-quality and efficient operation of the heating system:
- The supply of coolant to heating devices should be carried out in quantities that will ensure the heat balance of the room, subject to constantly changing outside temperatures anddepending on the temperature regime of the premises, determined by its owner.
- Reducing costs, including energy, to overcome hydraulic resistance.
- Reducing material costs when installing a heating system, also depending on the diameter of the pipelines being laid.
- Low noise, stability and reliability of heating devices.
How to correctly calculate the heating system
To calculate the heating in a private house, you need to know the required amount of heat. For this purpose, the heat losses of the entire house are calculated in the warm and cold seasons. This includes heat losses through window, doorways, building envelopes, etc. These are rather painstaking calculations. It is generally accepted that on average a heat source should produce 10 kW per 100 m2 heated area.
The heating system is understood as the relationship between a set of devices: pipelines, pumps, shut-off and control equipment, controls and automation for transferring heat from a source directly to the room.
Types of heating boilers
Before you make a hydraulic calculation of heating systems, you need to choose the right boiler (heat source). There are the following types of boilers: electric, gas, solid fuel, combined and others. The choice in most cases depends on the fuel prevailing in the area where you live.
Electric boiler
Due to power connection problems and the rather high price of electricity, this equipment has not gained wide distribution.
Gas boiler
In order to install such a boiler, a special separate room (boiler room) was previously required. This currently only applies to equipment with an open combustion chamber. This option is most common in places with gasification.
Solid fuel boiler
With the relative availability of fuel, this equipment is not very popular. There are some inconveniences during its operation. During the day, it is necessary to produce a firebox several times. In addition, the heat transfer regime is cyclical. The use of these boilers is facilitated (the number of furnaces is reduced) by using a bulb or fuel with a high combustion temperature, which increases the burning time due to the controlled air supply. This can also be done using water heat accumulators, to which central heating is connected.
Necessary parameters when calculating power
- Wud - specific power of the heat source (boiler) per building area of 10 m2, taking into account the climatic conditions of the region.
- S is the area of the heated room.
There are also generally accepted values of specific power, which depend on the climatic zone:
- Wud=0, 7-0, 9 - for the Southern region.
- Wud=1, 2-1, 5 - for the Central region.
- Wud=1, 5-2,0 - for the Northern region.
Formula for boiler power
Before embarking on such an important undertaking as the hydraulic calculation of heating systems, you need to determine the power of the heat source using the following formula:
Wcat=S×Wud/10.
For the convenience of calculation, we will take the average value of Wud for 1 kW, so we get that 10 kW should fall on 100 m2 heated area. As a result, the installation schemes of the heating system will depend on the area of the house.
In other cases, forced circulation of the coolant is used using circulation pumps.
Two-pipe system
This is a classic version of the heating system, which has proven itself in the best way for a long time of operation. The hydraulic calculation of a two-pipe heating system will be discussed below. Why is she called that? The thing is that the basis of the engineering concept was the installation of several pipelines through the floors of the building. A heater was connected to one riser with hot water on all floors, and chilled water from the heater was supplied to the pipeline laid nearby.
As a result, the coolant from the first device, which had not yet had time to cool down, entered the device, which was located on the floor below, and the circulating liquid had the same temperature as in the first one. Thus, the temperature of the coolant in the first and last pipelines was identical - this means thatheat transfer was the same.
Two-pipe heating system - benefits
Central heating in a private house with a two-pipe system has the following advantages:
- Even heated floor provides uniform heating of all appliances.
- Compared to a single-pipe system, much more rooms can be fully heated.
- Temperature control in each specific room.
Settlement and graphic activities
When performing a complex hydraulic calculation of heating systems, first of all, it is necessary to carry out a number of preliminary measures:
- The heat balance of the heated building is determined.
- The type of heating devices is selected, after which they are schematically placed on the floor plan.
- Next, a decision is made on the placement of all heating units, the type and materials of pipelines, control and locking devices.
- To make a hydraulic calculation of heating systems, you will need to draw a schematic diagram in axonometry indicating the calculated loads and lengths of sections.
- The main ring is determined - this is a closed segment, which includes sections of pipelines located in series that have the maximum coolant flow from the heat source to the most remote heating device.
For settlementthe section is accepted as one that has a constant coolant flow rate and the same cross section.
Example of hydraulic calculation of a heating system
On the calculated segment, the heat load is equal to the heat flow that must be transferred on the supply pipeline, and on the return pipeline it has already transferred the circulating liquid that passed through this section.
Heat carrier consumption Gi-j, kg/h is calculated by the following formula:
Gi-j=0, 86×Qi -j/(t2-t0), where
Gi-j is the amount of heat in the calculated segment i-j;
t2-t0 are the design temperatures of the hot and cold liquid respectively.
How to choose the diameter of pipelines
To reduce the cost of overcoming resistance during the movement of the circulating fluid, the diameters of the pipelines should be located within the minimum coolant velocity required to remove air bubbles that contribute to the appearance of air locks. To reduce them, the diameter of the pipelines is brought to a minimum value that does not lead to hydraulic noise in the fittings and pipes of the system.
All production pipelines are divided into polymer and metal. The former are more durable, the latter are mechanically stronger. Which pipes to use in the heating system depends on its individual characteristics.
Hydraulic calculation of the heating system - program
Given the amount of work that needs to be done at the design stage, you can use specialized software.
Using the initial data, the program performs automatic selection of pipelines of the required diameter, performs preliminary adjustment of control and balancing valves, thermostatic valves and automatic regulators in the heating system. Also, the program can independently estimate what size heating devices will be required.
