Have you thought about installing water heating in your house? No wonder, because the one-pipe heating system of a private house can be traditional and absolutely energy independent or, on the contrary, very modern and fully automatic.
But you still have doubts about the reliability of this option - you do not know what scheme to choose and what \"pitfalls\" await you? We will help you clarify these issues - the article deals with the schemes of arrangement of one-pipe system, pros and cons awaiting the owner of the house with such a heating system. It is completed by a video showing the details and nuances of the one-pipe floor heating system.
- The principle of water heating
- The difference between one-pipe and two-pipe systems
- One-pipe heating variations
- Free and forced circulation systems
- Open or closed heating system?
- Effective single pipe system scheme
- How to connect the radiator to the mains
- Diagonal or cross connection
- Lateral or one-way connection
- Bottom connection of radiator to piping
- Benefits and disadvantages of the one-pipe system
- Conclusions and useful video on the topic
The working principle of water heating
The simple and reliable and economical single pipe system. The single pipe system remains the most popular way of organising individual heating. It functions by the continuous circulation of a liquid heat carrier.
Moving through the pipes from the heat source (boiler) to the heating elements and back, it releases its thermal energy and heats the building.
The heat carrier can be air, steam, water or antifreeze, which is used in houses of occasional residence. The most common are water heating schemes.
A considerable advantage of one-pipe heating systems is the minimal number of pipes, which condition the economic and aesthetic attractiveness of the scheme
Aesthetic qualities of one-pipe systems increase if metal-plastic and plastic pipes are used, because the pipe laying can be avoided.
In gravity heating systems, characterized by natural movement of the coolant, single-pipe circuits are exclusively built with top bore
In top bore circuits the supply pipe is located above the appliances, the coolant flows in series from one to the other and cools down on the way. To evenly distribute the coolant set bypass set before the radiators, which partially cuts off the supply of hot water
A similar principle is built by the vertical circuits of forced heating systems, in which the movement of hot water by the circulating pump
The direction of hot and cold water in the system, they are divided into downtrodden and dead-end. The dead-end hot and cold coolant moves in different directions, in the associated - to one side
One-pipe heating circuits with bottom bred connection supply and exhaust pipe is made from the bottom
The system with horizontal breding necessarily present circulating pump, without which the coolant movement will be too complicated. Mechanical or automatic air vents
Aesthetic advantages of the one-pipe heating system
Concealed installation of the one-pipe heating circuit
Single pipe heating gravity type
Improved one pipe circuit with a shorting the vertical plumbing heating schemes
The vertical plumbing heating schemes
The dead-end version of a one-pipe heating system
The lower plumbing version of a one pipe heating system
The horizontal plumbing systems
Traditional heating is based on phenomena and the laws of physics - thermal expansion of water convection and gravity. When heated by the boiler, the heating medium expands and creates pressure in the pipes.
It also becomes less dense and therefore lighter. The heavier and denser cold water, pushed from below, rushes upwards, so the pipe coming out of the boiler is always directed upwards as much as possible.
At the created pressure, convection and gravity the water goes to the radiators, heats them, cooling itself.
Thereby the heating medium gives off heat energy, heating the room. The water returns to the boiler already cold and the cycle starts all over again.
Modern equipment providing heat for the house can be very compact. It is not even necessary to allocate a special room for its installation
The heating system with natural circulation is also called gravity and gravity circulation. In order to ensure fluid movement, the angle of slope of horizontal branches of the pipeline must be observed, which should be 2 - 3 mm per running meter.
The volume of the coolant increases when heated, creating hydraulic pressure in the mains. However, since water is not compressible, even a small excess of it will lead to destruction of heating structures.
That is why any heating system is equipped with a compensating device - expansion tank.
The difference between one-pipe and two-pipe systems
Water heating systems are divided into two basic types - one-pipe and two-pipe. The difference between these schemes lies in the way the radiators are connected to the mains.
The one-pipe heating mains are a closed circular circuit. The pipeline is laid from the heating unit, the radiators are connected to it in series and lead back to the boiler.
Single-pipe heating is easy to install and does not have a large number of components, so it allows considerable savings on installation.
Single pipe heating circuits with natural movement of the coolant are arranged only with the upper distribution. A characteristic feature is that the schemes have risers for the supply line, but no risers for the return
The heating medium in two-pipe heating circuits moves through two lines. The first serves to deliver the hot coolant from the heating device to the heating circuits, the second - to withdraw the cooled water to the boiler.
The heating batteries are connected in parallel - the heated fluid enters each of them directly from the supply circuit, so it has almost the same temperature.
In the radiator the coolant gives energy and cooled leaves to the withdrawal circuit - \"return\". This scheme requires twice the number of fittings, pipes and fittings, but allows building complex branching structures and reducing heating costs due to the individual regulation of radiators.
Two-pipe system effectively heats large areas and multi-storey buildings. In low storey buildings (1-2 floors) with the area less than 150 square meters it is more reasonable to arrange one-pipe heating system both from aesthetic and economical point of view.
Two-pipe system of radiator connection is not very popular in individual heating systems in private houses as it is more difficult to mount and maintain. In addition, the doubled number of pipes looks unaesthetic
Single-pipe heating arrangement options
Elements of any heating system:
- heat source - boiler (solid fuel, electric, gas boiler;)
- heating devices - radiators, warm floor circuits;
- the device that ensures the circulation of heat - a special dispersed section of the main line, a water pump;
- device for compensating the overpressure of the heating medium in the main - open-type or closed-type expansion tank;
- pipes, fittings and corresponding plumbing fittings.
Depending on the type of devices used, the heating scheme will also depend.
Heating solid fuel boiler unit
Electric boiler in a stand-alone scheme
Gas floor standing boiler unit
Wall boiler for summer houses and flats
Free and forced circulation systems
The heating medium circulation in the heating system can be natural - by means of physical phenomena or by forced circulation - by means of a circulation pump.
In the first case, the heating movement through the system is spontaneous and is called natural, in the second - forced or artificial.
Focusing on design features, single-pipe heating schemes are divided into two types. The first is the obsolete but simple flow circuit, the second is an advanced circuit with bypasses
To allow fluid movement in a gravity system, an acceleration section is necessary. This is a vertical branch pipe departing from the boiler, along which the heated medium rises.
At the top point, the pipe is gently turned down, so the water rushes with acceleration along the mains.
For the upper heating scheme, and also for two-story houses, this section is the supply pipe, as it rises to a sufficient level.
For heating of a single-storey building with bottom horizontal distribution, a surge collector shall be provided whose height shall not be less than 1.5 m from the level of the first radiator.
The surge section is a device for circulating the heating medium in a gravity-flow heating system. The pipe diameter of this line section shall be larger than that of the main part.
For example, if the main pipe diameter is 25-32 mm, a pipe of 40 mm diameter is selected for the runaway collector.
The highest point of the runaway collector shall be arranged in a convenient location near the boiler. The collector pipe shall be lowered in such a way as to provide sufficient height difference between the lower outlet of the header and the lower point of the main to maintain a constant pipe slope
The main advantages of the gravity system are the complete energy independence (in combination with a solid fuel boiler), simplicity and absence of complicated appliances.
Disadvantages, however, are many:
- To minimize hydraulic resistance, pipe diameters must be large enough.
- Every built-in appliance and device creates obstacles to fluid movement, so the system has a minimum of shut-off valves. This makes it difficult to repair as it requires complete shutdown of the system and draining of the mains.
- For reliable operation the gravity system must be carefully calculated and balanced by selecting the optimum pipe diameters and number of radiator sections. The outermost radiators in the system must be larger than those to which the coolant enters after leaving the boiler.
Installation of a circulation pump in the system neutralizes almost all of its disadvantages. The device gives the coolant an additional impulse, allowing it to overcome the hydraulic resistance of the pipeline elements.
Systems of forced single-pipe heating are realized in private houses most often.
Thanks to the modernization of the flow system by installing bypasses, the coolant with a working temperature flows almost simultaneously to all appliances
The pump can be mounted anywhere in the main line. But it is worth bearing in mind that hot water reduces its service life by affecting the rubber parts (gaskets and seals).
It is therefore advisable to install the unit in the return pipe, where the coolant circulates. A coarse filter must be included in front of it in order to protect against possible impurities.
All appliances and devices in heating systems should preferably be connected via shut-off valves and bypasses.
This installation allows the repair and maintenance of individual elements without having to stop the whole system and completely drain the water.
Bypasses are unregulated and regulated. In the first case, it is a simple branch pipe connecting the supply and return pipes. In the second case it is equipped with a three-way shut-off valve
The advantages of the forced circulation heating system:
- You can implement more complex and branched schemes, increase the length of circuits;
- No need for increased pipe diameters - the pump creates pressure in the pipeline sufficient for movement and uniform distribution of the liquid;
- Circulation occurs at a given rate and does not depend on the degree of heating of the coolant and the presence of dispersing section;
- No need to observe the slope angles when laying the pipeline, as.
It is also possible to install regulating devices at each radiator and keep the heating mode optimally maintained, thus reducing energy costs and heating expenses.
Disadvantages of single-pipe forced heating are only three:
- dependence on electricity;
- noise-some hum produced by a working pump;
- costthe higher unit cost compared to a gravity scheme.
It is quite easy to counteract them. The energy dependence is solved by the installation of an autonomous power generator or the possibility to switch the system to a mode with natural circulation.
To make the pump almost inaudible, it is enough to install it in a non-residential room - bathroom, toilet, boiler room.
At the top points of the line, especially with forced heating with a closed expansion tank, the possibility to bleed air released from water must be provided. For radiators these are automatic air vent valves or Maevsky cocks, for pipes - air separator
Open or closed heating system?
In order to avoid excessive increase of hydraulic pressure in the system and its jumps an expansion tank is installed. It takes in excess water when it expands and then returns it to the mains when it cools down, restoring the equilibrium of the system.
There are two fundamentally different designs, which determine the appearance of the whole system.
The open expansion tank is a partially or completely open vessel that is connected to the main at its highest point, immediately after the boiler.
In order to avoid overflow of liquid over the edges at a certain level, a branch line is provided through which the excess water will be discharged to the sewer or to the street.
In single story houses, the compensating tank is often led to the attic - in this case it must be insulated.
To avoid constant monitoring of the coolant level, a water line is supplied to the expansion tank and a simple float valve is installed
The heating system with this compensating device is called an open one. It is used in an energy-independent or combined heating system.
It involves direct contact between the hot coolant and the air resulting in natural evaporation and oxygenation.
Hence the following disadvantages characterize the open circuit heating system:
- In gravity systems piping must be laid with slopes, in which case the air released in the system is vented to tank and the atmosphere.
- The volume of water in the tank must be regularly checked and timely replenished to prevent excessive evaporation.
- Antifreeze must not be used as a heat transfer medium as its evaporation releases toxic substances.
The oxygen in the circulating fluid causes corrosion damage in the steel parts of heating appliances, reducing their service life.
However, it has the following advantages:
- No need for constant pressure control in the system;
- Even with small leaks the system will heat the house properly as long as there is enough fluid in the system;
- Fill the system fluid even with a bucket - just pour the expansion vessel to the required level.
The closed expansion tank is a rugged sealed casing whose inner volume is divided into two parts by a membrane. One cavity is filled with air, the other is connected to the pipe.
When heated, the heating medium increases in volume and presses the membrane towards the air chamber, which acts as a damper. When the water cools, the hydraulic pressure is reduced and the compressed air brings the system to equilibrium, squeezing the excess water back into the piping.
All closed-type tanks are equipped with an air valve. In an emergency, when the pressure in the air chamber exceeds the allowable limit, it bleeds the gas and prevents the unit from destroying
A system with a membrane-type expansion tank is called closed. It is a completely air-free closed hydraulic line.
The compensating tank can be installed anywhere in the system, but most often it is installed on the return pipe near the boiler - to improve serviceability.
A closed heating system is characterized by a small excess pressure. Therefore a safety group becomes an obligatory part of the line.
Assembly consists of an air vent, a pressure gauge and a safety valve for the discharge of the heating medium in case of emergency. It is mounted with a shut-off valve in the supply pipe to enable disconnection in case of repair.
If there is a pipe elevation, it is located at the upper point of the pipe.
Safety Group components
Positioning of the components
Feasibility study single-pipe system
Many factors are taken into account when designing a heating system - the availability of a stable electricity supply and a separate room for the equipment (boiler room boiler room), the number of floors and the layout, the aesthetics of the future construction, etc. etc.
In each case the location of the equipment and the way it is connected will differ.
For a very small room - a holiday home - the most effective is a simple gravity scheme of successive inclusion of batteries directly in the main pipe.
The installation of two or three radiators does not require a large number of shut-off valves - in this case it is easier to drain the system if necessary.
In buildings with a larger area the heat supply system is complex, sometimes branched In this case the best option is forced heating according to the \"Leningradka\" scheme with diagonal connection of the radiators and adjustable by-passes.
This scheme ensures maximum heating of the radiator area and the possibility to adjust and set the operation mode. To disconnect any of the system elements, it is not necessary to drain the whole main
The ways of connecting the radiator to the main
The heat output of the radiators depends on the way they are connected to the main.
There are three main types of connection:
Let us look at each of these in detail.
Diagonal or cross connection
The diagonal or cross connection is the most effective. The radiator area is heated to its maximum and there is practically no heat loss.
In this arrangement, the supply pipe is connected to the top radiator socket and the return pipe to the bottom socket on the opposite side of the appliance. Only the diagonal connection is used for larger radiator sections.
Sideways or unidirectional connection
The lateral or unidirectional connection allows a uniform heating of all sections of the radiator.
Feed and return pipes are connected on one side. This connection is most often used for top-draught heating.
The heat output of a radiator with side connection and top-down flow is 97%. When the heating medium flows backwards - from bottom to top - this figure is 78%
Bottom radiator connection to piping
Bottom connection is not the most efficient heating scheme. However, it is quite common, especially when the main pipe is hidden under the floor.
The supply and return pipes are connected to the bottom connections on different sides of the radiator.
The heat output of the bottom connection radiators is 88%
Benefits and drawbacks of single pipe system
Single pipe heating has gained wide popularity in the private construction field.
The main reasons are the relatively low cost of construction and the possibility to install it by yourself without involving specialists.
But the single pipe heating system also has other advantages:
- Hydraulic stability - the heat output of other elements of the system does not change when individual circuits are disconnected, radiators are replaced or sections are increased;
- The mains arrangement is circumvented by a minimum number of pipes;
- It is characterized by low inertia and heating time due to a smaller amount of coolant in the mains than in a two-pipe;
- Looks very aesthetically and does not spoil the decoration of the room, especially if the main pipe is hidden;
- The latest generation shut-off devices such as automatic and manual thermostatic valves allow a fine tuning of the operation of the whole system as well as of the individual elements;
- Simple and reliable design;
- Easy installation, maintenance and operation.
When the control and monitoring devices are connected to the heating system, it can be set to fully automatic operation.
It is possible to integrate it into a \"Smart House\" system - in this case optimal heating programs can be set according to time of day, season and other crucial factors.
The single pipe heating manifold can be fully concealed by the finish finish. Such a device not only does not spoil the appearance of the room, but also becomes a part of it - a piece of furniture
The main disadvantage of single pipe heating is the unbalanced heating of the radiators along the main line. Because of this, radiators installed far away from the boiler heat up less than radiators installed close to it. Therefore it is recommended to install cast-iron radiators which cool down slowly.
Installation of a circulation pump enables the heating medium to heat the heating circuits more evenly, but if the pipe length is sufficient there is considerable cooling.
There are two ways to reduce the negative effect of this phenomenon:
- In radiators far from the boiler the number of sections is increased. This increases their heat conductive area and the amount of heat emitted, allowing the rooms to heat more evenly.
- Design with a rational arrangement of heat emitters by rooms - the most powerful are installed in children, bedrooms and \"cold\" (northern, corner) rooms. As the heat carrier cools down, the living room and the kitchen go on, ending with non-residential and outbuildings.
Such measures minimize the disadvantages of the single-pipe system, especially for one- and two-storey buildings with up to 150 m² of floor area. For these houses, single-pipe heating is the most advantageous.
Conclusions and useful video on the subject
Not only radiators but also underfloor heating circuits are connected to the single pipe heating mains. The video shows how to make such an installation.
Single-pipe heating is a simple and reliable system. However, for efficient heating, it is necessary to carefully choose its individual elements. For this it is advisable to consult an expert, who will help you make an estimate.
You do not agree with the schemes in our article? Or have practical experience in the arrangement of single-pipe heating in a private home? Your experience will be useful to our readers. Feel free to share your knowledge in the comments below.