Two-pipe heating system of a multi-storey building and its scheme: how it works - Setafi

A two-pipe heating system involves the use of 2 different pipes for supplying and discharging water. Thanks to this, each radiator heats up quickly, there are no temperature and pressure drops. It is this scheme that is almost always implemented in apartment buildings. How it is arranged, and what types of structures are, is described in the presented material.

Scheme of a two-pipe system

The name of the system reflects its essence. It consists of 2 pipes, one of which brings water to the radiators, and the other takes the coolant away from them. The diagram of a two-pipe heating system clearly shows how it differs from a 1-pipe one. In the latter case, the role of the inlet and outlet circuit is played by the same pipe.

The scheme of two-pipe heating is fundamentally different. The system works like this:

1. The liquid is heated in the boiler and enters the supply pipe, marked in red.
2. From it, it moves into each radiator.
3. The cooled water, marked in blue, enters the return pipe, which is also called the return pipe.
4. Then it moves again to the boiler, after which it heats up.
5. Then it enters the radiators again, and the cycle is repeated many times.

The scheme of a two-pipe heating system of a multi-storey building is quite simple. It consists of several elements, indicated by numbers:

1. A boiler that heats water. In private houses, it is usually placed in the basement or in a separate room. In apartment buildings, it is located in the nearest boiler room.
2. Air vent - a device that bleeds excess air from the circuit. It works in automatic mode, for this it is equipped with a sensor.
3. A thermostatic valve is installed at the inlet to each battery. It allows you to control the temperature at approximately the same level.
4. Actually the radiator is a heating battery.
5. A device that allows you to balance the flow rate and evenly distribute pressure throughout the system.
6. Expansion tank.
7. Valve.
8. Filter for water purification.
9. The scheme of a two-pipe heating system of a multi-storey building necessarily provides for the presence of a circulation pump. It provides a forced flow of water, so that it freely reaches the upper floors.
10.  A sensor that controls the temperature.
11.  Safety valve for prevention of emergencies.

Advantages and disadvantages of the system

The two-pipe heating system in an apartment building has been increasingly used in recent decades. Compared to single-pipe, it has quite a few undeniable advantages:

1. Heat losses are minimal - hot water is suitable for each radiator, the temperature of which practically corresponds to the degree of heating of the boiler.
2. The room heats up much faster, both small and large areas.
3. There is no heat loss from one radiator to another (in the case of a single-circuit system, they are).
4. A two-pipe heating system with an upper wiring, as well as a lower one, allows you to individually adjust the temperature in each particular radiator.
5. In the event of an accident, repair or during maintenance work, it is not necessary to shut down the entire system. To find and fix a malfunction, it is enough to inspect a specific radiator or part of the network - the rest of the sections will work without interruption.
6. The two-pipe heating system of a multi-storey building is more resistant to complete defrosting of the system, so the risks of an accident are much lower.

There are not so many disadvantages of such a scheme, but nevertheless they also exist:

1. More materials are required (2 pipes instead of one) - accordingly, the installation price will be higher.
2. Installation work is more difficult to carry out compared to a 1-pipe circuit.
3. Since 2 pipes are used at once, it will be more difficult to embed them into the wall, the niche will be more difficult - more space will be required. In this regard, the single-pipe circuit looks more aesthetically pleasing.

Types of two-pipe system

There are 2 main classifications of such a system, they differ in design features. These parameters are of great importance in the design of buildings, as well as in terms of saving space and materials.

Top and bottom wiring

Depending on how the riser with the supply pipe is located, two types are distinguished:

1. Two-pipe system with top wiring - in this case, the supply pipe is always vertical, and each radiator is connected in parallel to it. Heated water first enters the attic, and then sequentially enters each apartment from the top floor to the next, reaching the first and then going down to the basement.
2. Bottom wiring a two-pipe heating system involves the movement of water not from top to bottom, but vice versa - from bottom to top. Moreover, the supply pipe, as can be seen in the diagram, is installed together with the return pipe (parallel to each other).

Horizontal and vertical layout

Depending on the location of the riser, 2 schemes are distinguished:

1. vertical (the riser is installed vertically, usually in the corner of a room or other room).
2. Horizontal (the riser is horizontally parallel to the floor).

In many houses, pipes are mounted vertically, since in this case you can save on materials and simplify installation. But in aesthetic terms, the horizontal scheme wins, since the pipes go down and are almost invisible. In new buildings, they are often installed directly into the floor, which allows you to achieve the perfect result.

Passing and dead end scheme

Single-pipe and two-pipe heating systems, their schemes differ in design features. But even within the 2-loop scheme, there are several varieties. Another classification is related to the direction of movement of water or other heat carrier. According to this indicator, 2 types are distinguished:

1. With passing traffic.
2. With dead-end circulation.

In the first case, the water in the supply line and in the return line move parallel to each other. In the second, their directions are opposite. In the latter case, the name "Tichelmann's loop" is often used. This is due to the fact that an additional pipe is placed between the first and last radiators - a “loop”, which performs the function of a return.

This ensures even distribution of heat in each battery. Such a scheme of a two-pipe forced circulation heating system is implemented in all modern multi-storey buildings.

As for the dead-end type with the opposite movement of water, it is used only in private or low-rise buildings. The fact is that very hot water enters the first radiator, and cooler water enters each subsequent battery. But if the circuit is not very long, heat loss is practically not noticeable.

A two-pipe heating system in a multi-storey building is usually designed so that temperature and pressure are evenly distributed. Thanks to this, all rooms warm up at the same rate, and the risks of water hammer and an emergency are minimized. This is how a two-pipe heating system works.