This manual is intended for owners of small private houses who seek to independently organize heating of their homes in order to save money. The most rational solution for such buildings is a closed heating system (abbreviated as - ЗСО), functioning with excess pressure of the coolant. Consider its working principle, varieties of wiring diagrams and a do-it-yourself device.
The principle of operation of closed CO
A closed (otherwise - closed) heating system is a network of pipelines and heating devices in which the coolant is completely isolated from the atmosphere and moves forcibly - from the circulation pump. Any ZSO necessarily includes such elements:
- heating unit - gas, solid fuel or electric boiler;
- safety group consisting of pressure gauge, safety and air valve;
- heating devices - radiators or contours of underfloor heating;
- connecting pipelines;
- a pump pumping water or non-freezing fluid through pipes and batteries;
- coarse mesh filter (sump);
- closed expansion tank equipped with a membrane (rubber "bulb");
- shut-off valves, balancing valves.
Note. Depending on the scheme, the composition of the ZOZ additionally includes modern devices for regulating the temperature and flow rate of the coolant - radiator thermal heads, check and three-way valves, thermostats and the like.
The algorithm of the closed-type system with forced circulation is as follows:
- After assembly and pressure testing, the pipeline network is filled with water until the pressure gauge shows a minimum pressure of 1 Bar.
- An automatic air vent of the safety group releases air from the system during the filling process. He is also engaged in the removal of gases that accumulate in the pipes during operation.
- The next step is to turn on the pump, start the boiler and warm up the coolant.
- As a result of heating, the pressure inside the SCZ increases to 1.5–2 bar.
- The increase in volume of hot water is compensated by a membrane expansion tank.
- If the pressure rises above a critical point (usually 3 Bar), the safety valve will release excess fluid.
- Once every 1-2 years, the system must undergo a process of emptying and flushing.
The principle of operation of the ZSO of an apartment building is absolutely identical - the movement of the coolant through pipes and radiators is provided by network pumps located in an industrial boiler room. Expansion tanks are also located there, the mixing or elevator unit is engaged in temperature control.
Positive qualities and weaknesses
The main differences between closed heat supply networks and outdated open systems with natural circulation are the lack of contact with the atmosphere and the use of transfer pumps. This gives rise to a number of advantages:
- the required pipe diameters are reduced by 2-3 times;
- slopes of highways are made minimal, since they serve to drain water for washing or repair;
- the coolant is not lost by evaporation from an open tank, respectively, you can safely fill pipelines and batteries with antifreeze;
- ZSO is more economical in terms of heating efficiency and cost of materials;
- Indoor heating is better regulated and automated, can act in conjunction with solar collectors;
- forced flow of the coolant allows you to organize floor heating pipes, monolithic inside the screed or in the grooves of the walls.
The gravitational (gravity-flowing) open system outperforms the SOA in terms of energy independence - the latter is unable to operate normally without a circulation pump. The second moment: in a closed network contains much less water and in case of overheating, for example, a TT-boiler, there is a high probability of boiling and the formation of a steam plug.
Reference. The boiler is saved from boiling by a safety relief valve plus a buffer tank that absorbs excess heat.
Types of closed systems
Before you buy heating equipment, pipe fittings and materials, you need to choose the preferred option for a closed water system. The master plumbers practice the installation of four basic schemes:
- Monotube with vertical and horizontal wiring (Leningradka).
- Collector, otherwise - radiation.
- Two-pipe dead end with shoulders of the same or different length.
- Tichelman loop - ring wiring with the associated movement of water.
Additional Information. Closed heating systems also include underfloor heating. The calculation and arrangement of floor circuits is much more complicated than the assembly of radiator heating, it is not recommended for beginners to undertake such installation.
We propose to consider each scheme separately, analyzing the pros and cons. As an example, take the project of a one-story private house of 100 m² with an attached boiler room, whose layout is shown in the drawing. The amount of heat load for heating has already been calculated according to the instructions, the required amount of heat is indicated for each room.
Installation of wiring elements and connection to a heat source is approximately the same. The installation of the circulation pump is usually provided in the return, in front of it is mounted a dirt collector, a feed pipe with a tap and an expansion tank (if you look downstream). A typical piping of a solid fuel and gas boiler is presented in the diagrams.
Read more about the installation and connection methods of heating units using various energy sources in separate manuals:
- TT boiler;
- gas heater;
- electric heat generator.
Single pipe wiring
The popular horizontal scheme "Leningradka" is one ring highway of increased diameter, to which all heating devices are connected. Passing through the pipe, the flow of heated coolant is divided on each tee and flows into the battery, as shown in the sketch below.
After transferring heat to the room, the cooled water returns back to the main, mixes with the main stream and moves to the next radiator. Accordingly, the second heating device receives water cooled by 1-3 degrees, and again takes the right amount of heat from it.
Result: colder water comes into each subsequent radiator. This imposes certain restrictions on a closed one-pipe system:
- The heat transfer of the third, fourth and subsequent batteries must be calculated with a margin of 10-30%, adding additional sections.
- The minimum trunk diameter is DN20 (internal). The outer size of the PPR pipes will be 32 mm, metal and cross-linked polyethylene - 26 mm.
- The cross-section of the inlet pipes to the heaters is DN10, the outer diameter is 20 and 16 mm for PPR and PEX, respectively.
- The maximum number of heaters in one ring of the Leningrad is 6 pcs. If you take more, there will be problems with increasing the number of sections of the last radiators and increasing the diameter of the distributing pipe.
- The cross section of the annular pipeline does not decrease throughout.
Reference. Single-pipe wiring is vertical - with the lower or upper distribution of the coolant to the risers. Similar systems are used to organize gravity flow in two-story private cottages or work under pressure in old-built apartment buildings.
A one-pipe closed-type heating system will cost inexpensively if it is soldered from polypropylene.In other cases, it decently hits the pocket due to the price of the main pipe and large fittings (tees). What “Leningradka” looks like in our one-story house is shown in the drawing.
Since the total number of heating devices exceeds 6 pcs., The system is divided into 2 rings with a common reverse manifold. The inconvenience of installing a single pipe wiring is noticeable - you have to cross the doorways. Reducing the flow in one radiator causes a change in water flow in the remaining batteries, so balancing the "Leningrad" is to coordinate the operation of all heaters.
Benefits of the beam scheme
Why the collector system was so named is clearly seen in the presented diagram. From the comb installed in the center of the building, individual coolant supply lines to each heating device diverge. Eyeliners are laid in the form of rays along the shortest path - under the floors.
The collector of the closed radiation system is directly fed from the boiler, the circulation in all circuits is provided by a single pump located in the furnace. In order to protect the branches from airing during the filling process, automatic valves - air vents are installed on the comb.
Strengths of the collector system:
- the scheme is energy efficient, since it allows you to clearly dose the amount of coolant sent to each radiator;
- the heating network is easy to fit into any interior - the supply pipes can be hidden in the floor, walls or behind a suspended (suspended) ceiling;
- hydraulic balancing of the branches is carried out using manual valves and flow meters (rotameters) mounted on the manifold;
- all batteries are supplied with water of the same temperature;
- the operation of the circuit is easy to automate - the control valves of the collector are equipped with servos that close the duct by the signal of thermostats;
- ZSO of this type is suitable for cottages of any size and number of storeys - at each level of the building there is a separate collector that distributes heat to groups of batteries.
In terms of financial investment, a closed beam system is not too expensive. A lot of pipes are consumed, but their minimum diameter is 16 x 2 mm (DN10). Instead of a factory comb, it is quite possible to use a home-made, soldered from polypropylene tees or twisted from steel fittings. True, without rotameters, the adjustment of the heating network will have to be done with the help of radiator balancing valves.
There are few disadvantages of beam wiring, but they are worth attention:
- Flush mounting and testing of pipelines is carried out only at the stage of new construction or overhaul. It is unrealistic to lay radiator hoses in the floors of an inhabited house or apartment.
- The collector is highly desirable to be located in the center of the building, as shown in the drawing of a one-story house. The goal is to make connections to batteries of approximately the same length.
- In the event of a leak of a pipe monolithic in the screed, it is quite difficult to find the place of a defect without a thermal imager. Do not make connections in the screed, otherwise you run the risk of encountering the problem shown in the photo.
Two-pipe options
When installing autonomous heating of apartments and country houses, 2 varieties of such schemes are used:
- Dead end (another name - shoulder). Heated water is distributed to heating devices through one line, and is collected and flows back into the boiler along the second line.
- The Tichelman loop (associated wiring) is an annular two-pipe network where the heated and cooled coolant moves in one direction. The principle of operation is similar - the batteries receive hot water from one line, and the cooled one is dumped into the second pipeline - the return line.
Note. In a closed associated system, the return line starts from the first radiator, and the feed ends at the last. The scheme presented below will help to understand.
What is good deadlock closed heating system of a private house:
- the number of "shoulders" - dead ends - is limited only by the capacity of the boiler installation, so a two-pipe wiring is suitable for any building;
- pipes are laid open or closed inside building structures - at the request of the homeowner;
- as in the radiation scheme, equally hot water comes to all batteries;
- ZOZ perfectly gives in to regulation, automation and balancing;
- correctly spread “shoulders” do not cross doorways;
- at the cost of materials and installation, a dead-end wiring will cost less than a single-pipe if assembly is carried out with metal-plastic or polyethylene pipes.
Designing a closed shoulder system of a country house or apartment building with an area of up to 200 squares is not particularly difficult. Even if branches of different lengths are made, the scheme can be balanced by deep balancing. An example of wiring in a one-story building of 100 m² with two “shoulders” is shown above in the drawing.
Tip. When choosing the length of the branches, the heating load should be taken into account. The optimal number of batteries on each “shoulder” is from 4 to 6 pcs.
The Tichelman loop is an alternative to a closed two-pipe network, which involves combining a large number of heating devices (over 6 pcs.) Into a single ring. Take a look at the associated cabling diagram and pay attention: no matter what radiator the coolant flows through, the total length of the route will not change.
From here arises an almost perfect hydraulic equilibrium of the system - the resistance of all sections of the network is the same. This significant advantage of the Tichelman hinge over other closed wiring entails and the main drawback is that 2 highways will inevitably cross the doorway. Bypass options - under the floors and above the door jamb with the installation of automatic air vents.
The choice of the heating scheme of a country house
According to our expert Vladimir Sukhorukov, the rating of closed systems is as follows:
- Dead end two-pipe.
- Collector.
- Two-pipe passing.
- Single tube.
Hence the advice: you won’t be mistaken if for the house with an area of up to 200 m² you choose the first option - a dead-end scheme, it is suitable in any case. Radial wiring is inferior to it in two respects - price and the ability to install in rooms with finished decoration.
Regarding the selection of pipe diameters and installation, we will give several recommendations:
- If the area of the home does not exceed 200 m², it is not necessary to carry out calculations - use the expert advice on the video or take the cross-section of the pipelines according to the schemes above.
- When you need to “hang” more than six radiators on the branch wiring branch, increase the pipe diameter by 1 standard size - instead of DN15 (20 x 2 mm), take DN20 (25 x 2.5 mm) and lay down to the fifth battery. Then drive the lines with the smaller cross-section indicated initially (DN15).
- In a building under construction, it is better to do beam wiring and select radiators with a lower connection. Be sure to insulate the underground highways and protect them with plastic corrugation at the intersection of the walls.
- If you do not know how to solder polypropylene correctly, then it is better not to mess with PPR pipes. Install cross-linked polyethylene or metal-plastic heating on compression or press fittings.
- Do not lay pipe joints in walls or screed in order not to have problems with leaks in the future.
For reference. Latin letters DN according to European standards indicate the internal diameter of the nominal bore of the pipe.
Useful links for beginners
We understand that it is impossible to consider all the nuances of designing and installing closed systems with one's own hands within the framework of one publication. The newcomer will have to take many steps on the path to working heating, our other articles will help protect you from mistakes as much as possible:
- selection of a solid fuel boiler;
- which gas heat generators are better;
- how to choose and connect heating appliances;
- installation of a security group;
- installation of air vents;
- how to fill the pipeline network and remove air;
- what should be the pressure in the heat supply network.
When collecting information about installing a closed heating system, try to draw it from reliable sources. Do not listen to Uncle Vasya the plumber whose work you have never seen. As an example, we suggest that you familiarize yourself with the video material clearly indicating where to place the expansion tank and why: