A single-pipe heating system exists as an alternative to a two-pipe system. Having a comparable efficiency, distributing the coolant through a single pipe is a more economical option, since it becomes possible to save on pipes and fittings. For self-calculation and assembly of such heating, you should carefully study the principles of operation and methods of installation of its constituent elements.
Features of a single-pipe heating system
A single-pipe heating system is actually a closed ring of pipes through which the coolant circulates. In addition to the pipes themselves, there are two main elements in the heating main: a boiler and heating radiators. In addition, the system includes a manifold, shut-off and control valves, a safety group, an expansion tank, etc. auxiliary equipment.
The water heated by the boiler enters the main and is fed to the first heating radiator. After leaving it, the water is supplied through the main to the second heating radiator, etc. from the last radiator, the coolant returns to the boiler through the return pipe and the cycle repeats.
Since in each of the radiators, due to intensive heat exchange, the temperature of the coolant decreases, the heating of the last radiator will be minimal, while the first radiator may have the temperature at which the boiler is set.
This moment is the main feature of single-pipe systems. With an alternative two-pipe scheme, the coolant is distributed almost without loss of temperature through the supply pipe, from which water is taken through the branches to the radiators. Therefore, the temperature of each of the radiators will be almost the same. The appearance of some difference is possible only with a large length of the line.
There are three ways to solve the problem of insufficient heating of the last radiator in the ring of a single-pipe system:
- Raise the water temperature. This method is the easiest to implement, but in practice it is rarely used due to the increase in energy costs. In addition, there may be a problem of overheating of the first radiators in the system.
- Increasing the heat output of the terminal heaters. This is achieved by increasing the number of sections, which entails a significant increase in the cost of the entire structure.
- Inclusion in the circulation pump system. With an intensive circulation of the coolant, it does not have time to fully give off energy in the first radiators and is supplied hot even to the last heat exchangers. This method is the most common, because. small costs for the circulation pump are fully compensated by the ability not to increase the intensity of the boiler and do without powerful radiators in the last heat exchangers along the ring.
One-pipe heating scheme has the following advantages before alternative schemes:
- significant reduction in pipe consumption and components, which greatly reduces the cost of the entire assembly;
- Possibility to connect heaters both in series and in parallel;
- you can direct the coolant so that it first enters the rooms with the greatest heat loss.
At the same time, single-pipe options are also inherent some shortcomings:
- long warm-up the total volume of the coolant after a cold start;
- if the house has two or more floors, then the heating system will be quite difficult to balance. The upper floors will always warm up more efficiently than the lower ones.
- if it is necessary to repair one section, you will have to turn it off the whole system.
The main feature by which single-pipe heating options can differ is the coolant circulation scheme.
Its feature is the use of vertical risers and the possibility of installation in multi-storey buildings. In this case, the heating heat exchangers are connected in series, starting from the top floor. In addition, the presence of a vertical riser allows you to organize a gravity assembly that does not require the use of a circulation pump.
The coolant here will begin to move, flowing down under the influence of gravity along horizontal sections of pipes with a certain slope. In addition, the coolant will additionally move the force that occurs in the vertical risers due to the difference in the density of the coolant with different temperatures.
It is used only in one-story houses. It can be either gravity or forced circulation. All heating radiators in horizontal systems are connected in parallel. It is possible to create circuits with several loops connected through a collector.
In addition, there is a variant of single-pipe heating, in which the coolant passes not only through the radiator, but also in parallel through a small diameter pipe.
This allows you to create longer loops due to more efficient heat distribution along the entire length of the heating line. Such a scheme is called “Leningrad”.
Ways to connect radiators
Most models of radiator assemblies allow you to connect two of the structurally provided points: at the top and bottom on the sides of the radiator.
There are several basic connection types:
- diagonalwhen the supply pipe is included in the upper inlet on one side of the heater, and the outlet pipe is connected to the lower one on the opposite side. This is the most efficient way;
- sidein which the coolant is supplied and removed through a pair of holes located on one side of the heat exchanger;
- lowerwhen water enters and exits the radiator through the bottom pair of holes;
- single point connection. It is used only in extreme cases, when it is not possible to extend a second pipe to the radiator. For such a connection, special injector connection units, in which the pipes entering the radiator hole have different lengths.
The sequence of actions when assembling a one-pipe system is divided into several stages:
- boiler installation. Depending on its type and design, installation can be done either on the wall or on the floor. In any case, all fire safety rules must be observed;
- installation of a safety group consisting of a safety valve, an air vent and a pressure gauge. The safety valve ensures the discharge of the coolant when its pressure in the system rises above the established norm. The air vent automatically removes air from the heating line. The pressure gauge displays the actual pressure in the pipes. Install the safety group immediately after the boiler. It is strictly forbidden to install shut-off valves between the boiler and the safety group;
- pipeline assembly. For a gravity one-pipe scheme, after the boiler of the safety group, a vertical column of pipes of a larger diameter must follow than in the main line. The horizontal part of the highway should have a continuous slope of several degrees. Pipes can be either entirely metal, or metal-plastic, or reinforced polypropylene;
- radiators are mounted in the places determined by the project. Most often, mounting brackets mounted on the wall are used for this. With a diagonal connection, it makes sense to organize a slope of one or two degrees towards the drain. Unused openings are closed with plugs, a Mayevsky crane is installed in one of them to drive away air congestion;
- a return pipe is connected to the outlet of the latter in the ring, supplied to the boiler inlet;
- an expansion tank cuts into the return line through the tee. Its capacity is selected depending on the type of volume of the circulating coolant. For water, you should choose tank models with a capacity of about 10% of the volume poured into the pipes. For non-freezing, the tank must have a capacity of 20–25% of the volume used;
- if necessary, return circulation pump. The pump power is selected individually, based on the volume and features of the existing assembly. It is not recommended to use pumps with excess power, since this will not improve the operation of the heating, but will lead to its airing and noise;
- through a tee in the lowest part of the return pipe, a drain is connected with a tap to drain the coolant.
The characteristic features of single-pipe systems follow from their ring scheme and the sequential passage of the coolant through the radiators. First of all, it is an inevitable fact that the temperature of the last heater and return will always be much lower than in the first radiator.
Other features are most clearly manifested in gravity structures.
- The expansion tank must not be installed on the return, but at the highest point of the vertical column after the boiler. In this case, the tank can be of an open type.
- The boiler inlet should be as low as possible.. Ideally below floor level.
- The entire line after the vertical column must have a continuous slope. An elevated section of the pipeline can stop the system due to the accumulation of air and violation of the flow of water under the influence of gravity.
Therefore, at the planning stage, all these features should be taken into account.
On the network you can find a lot of reviews about the experience of operating single-pipe heating systems. Here are the most characteristic of them:
Hope, Nizhny Novgorod
We have been using this system for several years. Attracts the ability to independently regulate the temperature. Of the inconveniences, only that in severe frosts, water begins to evaporate from an open expansion tank. So it has to be topped up periodically.
The system does not cause any problems during operation. I use antifreeze as a coolant. So that in the event of a possible repair it would not be necessary to drain it entirely, I connected the radiators to the “American” and installed the taps.
Single pipe heating: video
This video shows the process of assembling single-pipe heating in a cottage
As follows from the reviews and the very essence of the single-pipe heating system, such a solution can be a good option for a small house.
The minimum material consumption, the possibility of refusing energy-dependent circulation pumps and, at the same time, good thermal efficiency, all this makes single-pipe heating very attractive for owners of suburban real estate.