A modern heating system is a demonstration of a completely new approach to its regulation. To date, this is not a preliminary setup before starting the system with facilitating the subsequent hydraulic mode of operation. Modern heating in a private house in the process has a constantly changing thermal regime. That requires the equipment not only to monitor changes when heating the room, but also to respond to them correctly.
Conditions for the effective operation of the system
There are some points, compliance with which will ensure high-quality and efficient operation of the heating system:
- The coolant must be supplied to the heating devices in quantities that will ensure the thermal balance of the room, subject to a constantly changing outdoor temperature and depending on the temperature regime of the premises determined by its owner.
- Cost reduction, including energy, to overcome hydraulic resistance.
- Lower material costs during installation of the heating system, which also depend on the diameter of the pipelines being laid.
- Low noise, stability and reliability of heating devices.
How to calculate the heating system correctly
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 season. This includes heat loss through window and doorways, building envelopes , etc. These are quite painstaking calculations. It is generally accepted that, on average, a heat source should produce 10 kW per 100 m 2 of heated area.
Under the heating system is understood the relationship between a set of devices: pipelines, pumps, shut-off and control equipment, control and automation equipment for transferring heat from a source directly to the room.
Types of heating boilers
Before making a hydraulic calculation of heating systems, it is necessary to choose the correct boiler (heat source). The following types of boilers are distinguished: electric, gas, solid fuel, combined and others. The choice in most cases depends on the fuel prevailing in the area of residence.
Electric boiler
Due to problems with the connection of capacities and a rather high price for electricity, this equipment has not found its wide distribution.
Gas boiler
To install such a boiler, a special separate room (boiler room) was previously required. Currently, this applies only to equipment with an open combustion chamber. A similar option is most common in places with gasification.
Solid fuel boiler
With the relative availability of fuel, this equipment is not very popular. During its operation, there are some inconveniences. During the day, it is necessary to produce a furnace several times. In addition, the heat transfer mode is cyclical in nature. The use of these boilers is facilitated (the number of furnaces is reduced) by using a thermal bulb or fuel with a high combustion temperature, due to which the burning time is increased due to the regulated air supply. Also, this can be done due to water heat accumulators, to which central heating is connected.
Necessary parameters when calculating power
- W beats - specific power of the heat source (boiler) per building area of 10 m 2 , 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:
- W beats = 0.7-0.9 - for the Southern region.
- W beats = 1.2-1.5 - for the Central region.
- W beats = 1.5-2.0 - for the Northern region.
Formula for boiler power
Before embarking on such an important event as hydraulic calculation of heating systems, you need to determine the power of the heat source by the following formula:
W cat = S × W beats / 10.
For the convenience of calculation, we take the average value of W beats per 1 kW, so we get that 10 kW should fall on 100 m 2 of the heated area. As a result, the installation of the heating system will depend on the area of the house.
In other cases, forced circulation of the coolant using circulation pumps is used.
Double 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. Hydraulic calculation of a two-pipe heating system will be considered below. Why is she called that? The thing is that the basis of the engineering plan was the installation of several pipelines through the floors of the building. A heating device was connected to one riser with hot water on all floors, and chilled water from the heater entered the nearby pipeline.
As a result, the coolant that had not yet had time to cool down from the first device entered the device, which was located a floor below, and the circulating liquid had the same temperature as in the first. Thus, the temperature of the coolant in the first and last pipelines was identical - this means that the heat transfer was the same.
Two-pipe heating system - advantages
Central heating in a private house with a two-pipe system has the following advantages:
- Each heated floor provides uniform heating of all appliances.
- Compared with a single-tube system, you can fully heat much more rooms.
- Regulation of temperature conditions in each specific room.
Settlement and graphic events
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 structure 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 shut-off devices.
- To make a hydraulic calculation of heating systems, you will need to draw a schematic diagram in a perspective view indicating the design loads and lengths of the sections.
- The main ring is determined - this is a closed segment, which includes consecutive sections of pipelines having a maximum flow rate of the coolant from the heat source to the most distant heating device.
The calculation section is the one that has a constant coolant flow rate and the same cross section.
Example of hydraulic calculation of a heating system
In the calculated segment, the heat load is equal to the heat flux, which must be transferred to the supply pipe, and already circulated fluid that passed through this section at the return.
The coolant flow rate G i - j , kg / h is calculated by the following formula:
G i - j = 0.86 × Q i - j / (t 2 -t 0 ), where
G i - j is the amount of heat in the calculated segment ij;
t 2 -t 0 are the calculated temperatures of hot and cold liquids, respectively.
How to choose a pipe diameter
To reduce the cost of overcoming the resistance during the movement of the circulating fluid, the diameters of the pipelines should be within the minimum coolant speed, which is required to remove air bubbles that contribute to the appearance of air jams. To reduce them, the diameter of the pipelines is reduced to a minimum value that does not lead to hydraulic noise in the valves and pipes of the system.
All production pipelines are divided into polymer and metal. The former are more durable, the latter are mechanically more durable. 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, presets the control and balancing valves, thermostatic valves and automatic regulators in the heating system. The program can also independently evaluate how large heating appliances will be required.