There is no need to talk much about the importance of a heat point in the general heat supply system. Thermal circuits of thermal units are involved both in the network and in the internal consumption system.
The concept of a heat point
The efficiency of use and the level of heat supply to the consumer directly depends on the correct functioning of the equipment.
In fact, a heating point is a legal border, which in itself implies equipping it with a set of control and measuring equipment. Thanks to this internal filling, the definition of mutual responsibility of the parties becomes more accessible. But before dealing with this, it is necessary to understand how the thermal diagrams of thermal nodes function and why they should be read.
How to determine the scheme of a thermal unit
When determining the scheme and equipment of a heat point, they rely on the technical characteristics of the local heat consumption system, the external branch of the network, the mode of operation of the systems and their sources.
In this section, you will get acquainted with the heat carrier flow charts - the thermal scheme of the thermal unit.
Detailed consideration will allow you to understand howconnection to a common collector is made, the pressure inside the network and relative to the coolant, the indicators of which directly depend on the heat consumption.
Important! In the case of connecting a thermal unit not to a collector, but to a heat network, the flow rate of the coolant of one branch is inevitably reflected in the flow rate of the other.
Analysis of the thermal unit scheme in detail
The figure shows two types of connections: a - in the case of connecting consumers directly to the collector; b - when joining a branch of the heating network.
The drawing reflects graphical changes in coolant flow rates in the event of such circumstances:
A - when connecting heating and water supply systems (hot) to the heat source collectors separately.
B - when connecting the same systems to an external heating network. Interestingly, the connection in this case is characterized by high rates of pressure loss in the system.
Considering the first option, it should be noted that the indicators of the total flow rate of the heat carrier increase synchronously with the flow rate for hot water supply (in mode I, II, III), while in the second, although the increase in the flow rate of the heating unit takes place be, along with it, the heating consumption indicators are automatically reduced.
Based on the described features of the thermal scheme of the thermal unit, we can conclude that as a result of the total flow rate of the coolant considered in the first variant, when it is applied in practiceis about 80% of the consumption when using the second prototype scheme.
The place of the scheme in design
When designing a scheme for a thermal heating unit in a residential area, provided that the heat supply system is closed, pay special attention to the choice of a scheme for connecting hot water heaters to the network. The selected project will determine the estimated flow rates of heat carriers, functions and control modes, etc.
The choice of the scheme of the thermal heating unit is primarily determined by the established thermal regime of the network. If the network operates according to the heating schedule, then the selection of the drawing is made on the basis of a feasibility study. In this case, parallel and mixed circuits of thermal heating units are compared.
Features of substation equipment
In order for the heat supply network of the house to function properly, the heating points are additionally installed:
- valves and valves;
- special filters that trap dirt particles;
- control and statistical instruments: thermostats, pressure gauges, flow meters;
- auxiliary or standby pumps.
Scheme symbols and how to read them
The figure above shows a schematic diagram of a thermal unit with a detailed description of all the constituent elements.
| Item number | Symbol |
| 1 | Three-way valve |
| 2 | Valve |
| 3 | Plug tap |
| 4, 12 | Mud-mud |
| 5 | Return valve |
| 6 | Throttle washer |
| 7 | V-fitting for thermometer |
| 8 | Thermometer |
| 9 | Manometer |
| 10 | Elevator |
| 11 | Teplometer |
| 13 | Water meter |
| 14 | Water flow controller |
| 15 | Sub-steam regulator |
| 16 | Valves in the system |
| 17 | Stroke line |
The designations on the diagrams of thermal units help to understand the functioning of the unit by studying the scheme.
Engineers, focusing on the drawings, can guess where the breakdown occurs in the network with observed problems, and quickly fix it. Thermal node diagrams will also come in handy if you are designing a new house. Such calculations are necessarily included in the package of project documentation, because without them it is impossible to performsystem installation and wiring throughout the house.
Information about what a drawing of a thermal system is and how to put it into practice will be useful to anyone who has encountered heating or water heaters at least once in their life.
We hope that the material given in the article will help you understand the basic concepts, understand how to determine the main nodes and points of designation of fundamental elements on the diagram.
