Designing your own heating system is far from easy. Even if the installers “plan” it, you need to be aware of many nuances. Firstly, to monitor their work, and secondly, to assess the need and feasibility of their proposals. For example, in last years The hydraulic arrow for heating is being intensively promoted. This is a small addition, the installation of which costs a considerable amount. In some cases it is very useful, in others you can easily do without it.
What is a hydraulic arrow and where is it installed?
The correct name for this device is a hydraulic arrow or hydraulic separator. It is a piece of round or square pipe with welded pipes. As a rule, there is nothing inside. In some cases there may be two grids. One (above) for better “discharge” of air bubbles, the second (bottom) for screening out contaminants.
In the heating system, the hydraulic arrow is placed between the boiler and consumers - heating circuits. It can be positioned both horizontally and vertically. Most often they are placed vertically. With this arrangement, an automatic air vent is installed at the top, and a shut-off valve at the bottom. Some of the water with accumulated dirt is periodically drained through the tap.
That is, it turns out that a vertically installed hydraulic separator, at the same time as its main functions, removes air and makes it possible to remove sludge.
Purpose and principle of operation
A hydraulic arrow is needed for branched systems in which several pumps are installed. It provides the required coolant flow for all pumps, regardless of their performance. That is, in other words, it serves for hydraulic decoupling of the heating system pumps. That’s why this device is also called a hydraulic separator or hydraulic separator.
A hydraulic arrow is installed if the system has several pumps: one on the boiler circuit, the rest on the heating circuits (radiators, water floor heating, indirect heating boiler). For correct operation, their performance is selected so that the boiler pump can pump a little more coolant (10-20%) than is required for the rest of the system.
Why do you need a hydraulic arrow for heating? Let's look at an example. In a heating system with several pumps, they often have different capacities. It often turns out that one pump is many times more powerful. All pumps have to be installed nearby - in the manifold unit, where they are hydraulically connected. When the powerful pump turns on full power, all other circuits remain without coolant. This happens all the time. To avoid such situations, they install a hydraulic arrow in the heating system. The second way is to spread the pumps over a long distance.
Operating modes
Theoretically, three modes of operation of a heating system with a hydraulic arrow are possible. They are shown in the figure below. The first is when the boiler pump pumps exactly the same amount of coolant as required by the entire heating system. This is an ideal situation in real life very rare. Let's explain why. Modern heating adjusts operation according to the temperature of the coolant or the temperature in the room. Let's imagine that everything was calculated perfectly, the valves were tightened, and after adjustment, equality was achieved. But after some time, the operating parameters of the boiler or one of the heating circuits will change. The equipment will adapt to the situation, and the equality of productivity will be violated. So this mode can last only a few minutes (or even less).
The second mode of operation of the hydraulic switch is when the flow rate of the heating circuits is greater than the power of the boiler pump (middle picture). This situation is dangerous for the system and should not be allowed to happen. This is possible if the pumps are selected incorrectly. Or rather, the boiler pump has too low a capacity. In this case, to ensure the required flow rate, coolant from the return line will be supplied to the circuits along with the heated coolant from the boiler. That is, at the boiler outlet, for example, 80°C, into the circuit after adding cold water is coming, for example 65°C (actual temperature depends on the flow deficit). Walking through heating devices, the coolant temperature drops by 20-25°C. That is, the temperature of the coolant supplied to the boiler will be, at best, 45°C. If we compare it with the output temperature - 80°C, then the temperature delta is too high for a conventional boiler (not a condensing boiler). This mode of operation is not normal and the boiler will quickly fail.
The third operating mode is when the boiler pump supplies more heated coolant than the heating circuits require (right figure). In this case, part of the heated coolant is returned back to the boiler. As a result, the temperature of the incoming coolant rises, and it operates in a gentle mode. This is the normal operating mode of a heating system with a hydraulic arrow.
When is a hydraulic arrow needed?
A hydraulic arrow for heating is 100% needed if the system will have several boilers operating in a cascade. Moreover, they must work simultaneously (at least most of the time). Here, for correct operation, a hydraulic separator is the best solution.
If there are two simultaneously operating boilers (in cascade), a hydraulic arrow is the best option
Another hydraulic arrow for heating can be useful for boilers with a cast iron heat exchanger. In the hydraulic separator tank, warm and cold water. This reduces the temperature delta at the boiler outlet and inlet. This is a blessing for a cast iron heat exchanger. But a bypass with a three-way adjustable valve will cope with the same task and will cost much less. So even for cast iron boilers located in small heating systems, with approximately the same flow rate, it is quite possible to do without connecting a hydraulic arrow.
When can I deliver
If the heating system has only one pump - on the boiler, a hydraulic arrow is not needed at all. You can get by if one or two pumps are installed per circuit. Such a system can be balanced using control valves. When is the installation of a hydraulic arrow justified? When the following conditions exist:
- There are three or more circuits, all of very different power (different circuit volumes, required different temperatures). In this case, even with perfectly accurate selection of pumps and calculation of parameters, there is a possibility of unstable operation of the system. For example, a situation often occurs when when turning on the pump heated floors, the radiators are getting cold. In this case, hydraulic isolation of the pumps is needed and therefore a hydraulic arrow is installed.
- In addition to radiators, there is a water-heated floor that heats large areas. Yes, it can be connected through the manifold and mixing unit, but it can force the boiler pump to work in extreme mode. If your heating pumps often burn, you most likely need to install a hydraulic arrow.
- In a medium or large volume system (with two or more pumps), you are going to install automatic control equipment - based on coolant temperature or air temperature. At the same time, you don’t want/can’t adjust the system manually (with taps).
In the first case, a hydraulic decoupling is most likely needed, in the second, it is worth thinking about installing it. Why just think? Because these are significant expenses. And it’s not just the cost of the hydraulic gun. It costs about $300. I'll have to put more optional equipment. At a minimum, you need manifolds at the inlet and outlet, pumps for each circuit (with a small system, you can do without them), as well as a pump speed control unit, since they can no longer be controlled through the boiler. Combined with the installation fee for the equipment, this “add-on” amounts to approximately two thousand dollars. Quite a lot indeed.
Why then install this equipment? Because with a hydraulic arrow, heating works more stable and does not require constant adjustment of the coolant flow in the circuits. If you ask the owners of cottages whose heating is made without a hydraulic separator, they will tell you that they often have to reconfigure the system - turn the valves, adjusting the flow of coolant in the circuits. This is typical if different heating elements are used. For example, there is a heated floor on the ground floor, radiators on two floors, heated utility rooms in which it is necessary to maintain minimum temperature(garage, for example). If you expect to have approximately the same system, but the prospect of “adjustment” does not suit you, you can install a hydraulic arrow for heating. If it is available, each circuit receives as much coolant as it requires at the moment and does not in any way depend on the operating parameters of nearby pumps in other circuits.
How to select parameters
The hydraulic separator is selected taking into account the maximum possible speed coolant flow. The fact is that at high speeds of liquid movement through the pipes, it begins to make noise. To avoid this effect, the maximum speed is assumed to be 0.2 m/s.
Parameters required for the hydraulic separator
By maximum coolant flow
To calculate the diameter of the hydraulic arrow using this method, the only thing you need to know is the maximum coolant flow that is possible in the system and the diameter of the pipes. With pipes everything is simple - you know which pipe you will use for wiring. We know the maximum flow that the boiler can provide (available in technical specifications), and the flow rate through the circuits depends on their size/volume and is determined when selecting circuit pumps. The flow rate for all circuits is added up and compared with the power of the boiler pump. A large value is substituted into the formula to calculate the volume of the hydraulic needle.
Let's give an example. Let the maximum flow rate in the system be 7.6 cubic meters/hour. The permissible maximum speed is taken as standard - 0.2 m/s, the diameter of the pipes is 6.3 cm (2.5 inch pipes). In this case we get: 18.9 * √ 7.6/0.2 = 18.9 * √38 = 18.9 * 6.16 = 116.424 mm. If we round, we find that the diameter of the hydraulic needle should be 116 mm.
According to the maximum boiler power
The second method is to select a hydraulic needle according to the boiler power. The estimate will be approximate, but can be trusted. The boiler power and the difference in coolant temperatures in the supply and return pipelines will be needed.
The calculation is also simple. Let the maximum boiler power be 50 kW, the temperature delta be 10°C, the diameters of the pipes be the same - 6.3 cm. Substituting the numbers, we get - 18.9 * √ 50 / 0.2 * 10 = 18.9 * √ 25 = 18.9*5 = 94.5 mm. Rounding, we get the diameter of the hydraulic needle 95 mm.
How to find the length of the hydraulic arrow
We have decided on the diameter of the hydraulic separator for heating, but we also need to know the length. It is selected depending on the diameter of the connected pipes. There are two types of hydraulic arrows for heating - with taps located one opposite the other and with alternating pipes (located offset from one another).
Determining the length of the hydraulic arrow from a round pipe
It is easy to calculate the length in this case - in the first case it is 12d, in the second - 13d. For medium-sized systems, you can select the diameter depending on the pipes - 3*d. As you can see, nothing complicated. You can calculate it yourself.
Buy or make your own?
As they said, a ready-made hydraulic arrow for heating costs a lot - $200-300 depending on the manufacturer. To reduce costs, there is a natural desire to do it yourself. If you know how to cook, no problem - we bought the materials and did it. But the following points must be taken into account:
- The threads on the bends must be well cut and symmetrical.
- The walls of the outlets are of the same thickness.
The quality of a homemade product may be “not very good”
It seems like obvious things. But you will be surprised how difficult it is to find four normal fittings with normally made threads. Further, all welds must be of high quality - the system will work under pressure. The bends are welded strictly perpendicular to the surface, at the required distance. In general, this is not such an easy task.
If you don’t know how to do it yourself, you’ll have to look for a performer. It’s not at all easy to find: either they charge a lot for the services, or the quality of the work is, to put it mildly, “not very good.” In general, many people decide to buy a hydraulic gun, despite the considerable cost. Moreover, recently, domestic manufacturers are making no worse, but much cheaper.
With several circuits, for all its multitasking, there is one serious drawback: it is not able to stably distribute heat across the circuits and quickly adapt to changes in the parameters of their work. As a result, the system very often becomes unbalanced. Only one device can solve the problem - a heating water gun. Why is it so useful and why is it needed? In order to clarify all the important points, let’s take a closer look at the device: what it is, how it works, what its types are, in what situations its use is recommended. And after that, thanks to the mini-instructions and video, we will learn how to make a hydraulic arrow with our own hands.
What is a hydraulic arrow
The hydraulic arrow is a simple hydraulic buffer in the form of a tube with several pipes. The advantage is made of heat-resistant steel. The hydraulic separator includes the following mandatory structural components:
- side pipes for supply;
- side return pipes;
- air vent - at the top end;
- drain - at the bottom end.
Through the supply pipes, the hydraulic needle is connected to the supply pipes of the system, and through the return pipes - to the return pipeline. Using an air vent, excess air is eliminated, which regularly accumulates in the upper zone of the hydraulic separator during operation. heating system. The air vent can be either automatic or mechanical - in the form of a Mayevsky tap. A drain is necessary to systematically remove dirt deposits that accumulate at the bottom of the device. There are no heating elements or coils inside the device - the pipe is hollow.
Hydraulic gun operation diagram
How does a hydraulic arrow work?
The main essence of the work of the hydraulic arrow is to separate the flows along different circuits of the heating system. The device can operate in three schemes.
- Scheme No. 1: The coolant is directly moved from the heating boiler into the heating system, then the pumps accelerate it along the circuits, and it flows back into the boiler through the hydraulic valve. In this case, the same coolant flow rates through the boiler and through the heating system are observed.
- Scheme No. 2: The coolant moves through the hydraulic arrow from the return line to the supply line. This scheme occurs if a low-power boiler with small-diameter ducts is used. It assumes that the flow through the heating system will be greater than through the heating boiler.
Important! In the second scheme, the boiler operates at the limit of its capabilities, which negatively affects both its service life and the quality of coolant circulation, so this option for operating the system is absolutely not allowed.
- Scheme No. 3: The coolant in a small volume moves through the hydraulic arrow from the supply line to the return line. The return flow enters the boiler heated, which increases its efficiency. This diagram assumes that the heat flow through the boiler is higher than through the heating system.
The most correct and effective option The operation of the hydraulic arrow is considered to be scheme No. 3.
Why do you need a hydraulic arrow?
The main task of this device is to stabilize the operation of a heating system with several circuits at once. If the house has more than one floor and each has radiators and, and the water is heated from a boiler, we can speak with complete confidence about increased coolant consumption. In such a powerful system, high dynamic pressure and problems with coolant pumping cannot be avoided, and this can lead to equipment imbalance. In order to avoid problems, it is important to separate the heating system and the heating boiler itself, as well as neutralize the dynamic influence of the circuits on each other - this is where a special hydraulic arrow will come to your aid.
Stainless steel hydraulic arrow
So, you cannot do without a hydraulic separator in the following situations:
- One wall-mounted boiler serves an extensive system with increased performance coolant flow.
- Two wall-mounted boilers serve the same extensive combined system.
- The powerful system is served by two boilers at once: wall-mounted and floor-mounted.
Among other things, one cannot fail to mention the advantages of the hydraulic gun:
- eliminating mutual influence of multifunctional heating system circuits;
- alignment of the hydrodynamic balance of the system;
- the ability to connect additional heating components to the system without negative consequences;
How to choose a hydraulic gun
In order to correctly select a hydraulic arrow, you should understand its types and the main functional parameters of the heating system for which it is purchased.
Hydraulic separators are classified according to several indicators:
- by type of section - round and square;
- by the number of supply and return pipes - devices with four, six or eight inputs/outputs;
- by volume;
- by methods of supply and removal of coolant;
- according to the location of the nozzles - placed along one axis or alternating.
Before you go to the store, you should calculate two the most important parameters operation of your heating system:
- power – the sum of the thermal power of absolutely all circuits;
- the volume of coolant pumped through the system.
Having this data in hand, compare them with the operating parameters of the hydraulic arrows being evaluated - all technical information about separating devices can be found in the attached data sheets.
Do-it-yourself hydraulic arrow
How to make a hydraulic arrow
If you don’t want to spend money on a hydraulic arrow, you can try to make it yourself. The main thing here is to correctly perform a number of calculations and have gas or electric welding skills.
First define optimal sizes hydraulic separator pipes:
- internal diameter: divide the sum of all heating boiler powers in kW by the temperature difference between the supply and return, extract from the resulting parameter Square root, and then multiply the last value by 49;
- Height: Multiply the inside diameter by six.
- spacing between pipes: multiply the internal diameter by two.
Based on the calculated parameters, draw up a drawing of the future hydraulic arrow. Then prepare a round or square steel tube corresponding to the calculated values and weld into it required amount pipes with threaded connections.
As we can see, if in the house a complex system heating, servicing large areas, you can’t do without a hydraulic gun. Fortunately, even despite complex principle work and a lot of tasks, this device is quite simple in design, so it’s realistic to do it yourself. So you always have a choice: either buy a hydraulic gun or trust your own skills.
When is it necessary to use a hydraulic arrow: video
Hydrostrelka: photo
A hydraulic arrow (hydraulic separator, hydraulic arrow) is an element of the heating system that allows different heating circuits to be connected to each other. The separator maintains a minimum pressure difference between circuits, which allows one or more circuits to be shut off without changing the pressure in the remaining circuits. In other words, the hydraulic arrow for heating eliminates the influence of the circulation pumps of the heat source on the pumps of the heat consumers and vice versa.
Note! As a rule, a hydraulic separator is used in branched heating systems where there are several circuits.
Why should you use a hydraulic boom?
Section of the heating system with a hydraulic arrow.
In heating systems where there are two or more heating circuits (radiators, heated floors, hot water), as a rule, the circuits are connected to each other by a common manifold. At the same time, the presence of a common collector can lead to the following problems:
- The circulation pumps of each circuit influence each other (especially if the pumps differ in power). To overcome the effects of a more powerful pump, the low-power pump must operate at its limit, consuming more electricity than required under “normal” conditions. At the same time, working at the limit of their capabilities, pumps fail earlier. In addition, under such conditions the pump cannot always provide the required performance;
Why is it needed for heating?
- Even if the circulation pump of one of the boilers was turned off, its radiators will still heat up (under the influence of the other pumps, coolant circulation in the turned off circuit will continue);
- Difficulties in calculating pump power for both the boiler and heating circuits. The boiler pump power should be selected taking into account the total power of the heat consumer pumps.
All of the above problems can be solved by a hydraulic arrow.
Side view of the arrow.
Note! In a hydraulic separator, the speed of movement of the coolant decreases sharply (by about 9 times), this is due to the fact that upon entering the separator, the diameter of the flow increases several times (usually 3 times). Thanks to this, pressure drops in the system are eliminated.
Design, purpose and principle of operation of the hydraulic arrow
The hydraulic arrow for heating consists of a bronze or steel body with two pipes for connecting to the boiler circuit (supply pipe + return pipe), as well as several pipes (usually 2) for connecting the heat consumer circuits. A drain valve is installed in the upper part of the hydraulic separator through a ball valve or mounted in the lower part. A special mesh is often installed inside the housing of factory hydraulic arrows, which allows small air bubbles to be directed into the air vent.
The hydraulic arrow for heating performs the following functions:
- Maintaining the hydraulic balance of the system. Turning on/off one of the circuits does not affect the hydraulic characteristics of the remaining circuits;
- Ensuring the safety of cast iron boiler heat exchangers. The use of a hydraulic arrow makes it possible to protect cast iron heat exchangers from sudden temperature changes (for example, when carrying out repair work when the circulation pump is turned off, or when the boiler is turned on for the first time). As is known, a sharp change in coolant temperature negatively affects cast iron heat exchangers;
- Air vent. The hydraulic arrow for heating performs the functions of removing air from the heating system. To do this, in the upper part of the device there is a pipe for installing an automatic air vent;
- Filling or draining coolant. Most of both factory-made and self-made hydraulic switches are equipped with drain valves, through which it is possible to fill or drain coolant from the system;
- Cleaning the system from mechanical contaminants. The low flow rate of the coolant in the hydraulic separator makes it an ideal device for collecting various mechanical contaminants (scale, scale, rust, sand and other sludge). Solid particles circulating through the heating system gradually accumulate in the lower part of the device, after which they can be removed through the drain valve. Some models of hydraulic arrows can be additionally equipped with magnetic catchers that attract metal particles.
Hydraulic arrow for heating Gidruss.
The process of removing mechanical particles through the drain valve:
- Turn off the boiler and circulation pumps;
- After the coolant has cooled, shut off the section of the pipeline where the drain valve is located;
- We put a hose of a suitable diameter on the drain tap, or, if space allows, we substitute a bucket or any other container;
- Open the tap and drain the coolant until it comes out pure water free of contaminants;
- Close the drain valve, and then open the blocked section of the pipeline;
- We subscribe the system and launch the equipment.
Video
- this is a rather complex “organism” for the effective functioning of which it is necessary to achieve maximum coordination and balancing of the work of all its elements. Achieving such “harmony” is not so easy, especially if the system is complex, branched, including several circuits that differ in operating principles and temperature conditions. In addition, heating circuits and individual heat exchange devices may have their own automatic adjustment and operation devices, which, through their intervention, should not affect functionality"neighbors".
There are several approaches to achieving such “unison”, but one of the simplest and effective ways is a very simple but very effective device - a hydraulic separator, or, as it is more often called, a hydraulic arrow for heating. What kind of element is this, what is the principle of its operation, how to correctly calculate and install it - in this publication.
Why is a hydraulic separator needed in a heating system?
To understand the purpose of the hydraulic arrow, let's remember how it works in general
- In its simplest form, a system with forced circulation you can imagine it like this.
The diagram is given with great simplification. Yes, it doesn’t show expansion tank and elements of the security group, simply for reasons of “lightening” the drawing.
K – boiler, provides heating of the coolant.
N1 is a circulation pump, thanks to which the coolant moves through the supply (red lines) and return (blue lines) pipes. The pump can be installed on a pipe or be part of the boiler structure - this is especially true for wall-mounted models.
Heating radiators (HR) are embedded in a closed loop of pipes, providing heat exchange - the thermal energy of the coolant is transferred to the premises of the house.
At correct selection circulation pump in terms of performance and the pressure created in the simplest single-circuit heating system, it may be quite sufficient in a single copy, and there seems to be no special need for installing additional devices. There will be a remark about this a little later.
Circulation pump is the most important element of the heating system
Although there are schemes with natural circulation of the coolant, you should still install a circulation pump - this will dramatically increase the efficiency of the heating system. How to choose, how to calculate the optimal parameters of the device - in a special publication on our portal.
- For small house such a simple scheme may be quite sufficient. But in a larger building it is often necessary to use several heating circuits. Let's complicate the scheme.
Can one pump cope with several circuits? Far from a fact... This figure shows that the pump ensures the movement of the coolant through the collector (Cl), from where it is disassembled into several different circuits. It can be:
— One or more high-temperature circuits with conventional radiators or convectors (RO).
- (HTP), for which the coolant temperature should already be significantly lower, which means special thermostatic devices will be used. The sensor length of underfloor heating circuits is also usually several times longer than conventional radiator wiring.
— Home security system hot water with the installation of an indirect heating boiler (IHB). Here there are very special requirements for the circulation of the coolant, since usually by changing the flow rate of the coolant flowing through the boiler, the heating temperature of the hot water is also regulated.
Will our only pump cope with such a load, with such a coolant flow rate? Probably not. Of course, there are models of high productivity and power, with high levels of generated pressure, but the capabilities of the boiler itself are not unlimited. Its heat exchanger and internal pipes are designed for a certain performance and pressure created, and these values should not be overestimated, as this may well lead to the failure of an expensive boiler installation.
And the pump itself, if it constantly works at the peak of its capabilities, providing coolant to all circuits of the branched system, is unlikely to last long. This is not even to mention the increased noise of powerful equipment and considerable energy consumption.
- What is the solution - to install on each circuit its own circulation pump, calculated according to the parameters of its “subsystem” that it serves.
So, each circuit has its own pump. Is the problem solved? Alas, this is far from true - it simply moved to a “different plane” and even worsened!
As a result, this often leads to unacceptable overheating of heated floors, uneven heating of various rooms, “locking” of circuits and other negative phenomena that nullify the efforts of the owners to create a highly efficient system.
And the worst thing in this case is for the pump installed near the boiler - all the instability of the system parameters is primarily reflected in its operation, and ultimately in the “torn-up” functioning of the boiler that cannot be precisely adjusted. But often in large houses two or more boilers are installed in cascade - managing such a system generally becomes an extremely difficult, almost impossible task. All this causes rapid wear and tear of expensive equipment.
- And the solution, it turns out, is quite simple - you need to divide all hydraulic system not only to the final consumption circuits, through the collector, but also to allocate a separate boiler circuit.
This is precisely the function that the hydraulic needle (HS) performs. This simple device is installed between the boiler and the collector.
The correct full name of the hydraulic arrow is hydraulic separator. It was called the arrow, apparently, because it is capable of redirecting the hydraulic flows of the coolant, ensuring the balance of the entire system as a whole.
The design of a conventional hydraulic arrow is extremely simple Structurally, this element is a hollow pipe of round or rectangular section, plugged at both ends, with two pairs of pipes - outlet, for supply, and inlet - for the return pipe.
In essence, two interconnected, but essentially independent of each other circuits are formed: a small boiler circuit and a large one, including a collector with all branches to the remaining circuits. Each of these two circuits has its own flow rate and speed of coolant, which do not have any significant effect on each other. Typically, the indicator Q1 is a stable value, since the boiler pump constantly operates at the same speed, Q2 is a value that changes during the current operation of the heating system.
Essentially, the system is divided into a small boiler circuit and a large one with heat exchange devices. The diameter of the pipe is selected in such a way as to create an area of reduced hydraulic resistance, which allows you to equalize the pressure in the small circuit and supply it regardless of the operation or downtime of the working circuits. In general, this leads to balanced operation of each section of the heating system, to smooth operation of the boiler equipment and the entire system as a whole, not subject to pressure and temperature surges.
How does a hydraulic separator work?
In principle, three modes of operation of the hydraulic separator are possible.
| Illustration | Description of the operating mode of the hydraulic gun |
|---|---|
 | This is an almost ideal, equilibrium state of the system. The pressure created by the boiler small circuit pump is equal to the total pressure of all heating circuits (Q1 = Q2). Temperatures at the inlet and outlet of the feed are equal (t1 = t3). A similar situation occurs on the return pipes. (t2 = t4). The vertical movement of the coolant is minimal or even absent. In practice, if such a situation occurs, it is extremely rare, sporadically, since the operating parameters of heating circuits tend to change periodically. |
 | Situation two. The total coolant flow in the heating circuits exceeds that of the boiler pump (Q1. Essentially, it can be described as the “demand” for water exceeds what the boiler can “offer.” The situation is quite common when most circuits are involved at the same time. In this case, a vertical upward flow is formed from the return pipe of the large circuit to the supply pipe. Moving upward, the vertical flow mixes with the hot coolant coming from the boiler. Temperature: t1 > t3, t2 = t4. |
 | The situation is diametrically opposite - the flow rate in the small circuit (without changing nominally) has become higher than the total in the heating circuits (Q1 > Q2). “Supply” exceeded “demand” for coolant. Typical reasons for this situation: – activation of thermostatic equipment on heating circuits or on an indirect heating boiler, temporarily turning off the coolant supply. – temporary complete shutdown of one or more circuits due to lack of demand for heating of certain premises. – temporary decommissioning of circuits for repair or maintenance work. – startup of boiler equipment for warming up, with gradual step-by-step connection of working circuits. Nothing critical happens - the boiler circuit works mostly on its own, pumping the main volume of coolant in a small circle. In the hydraulic arrow itself, a vertical downward flow is formed, from the supply to the “return”. Temperature: t1 = t3, t2 > t4. In this mode of operation, the temperature in the “return” quickly enough reaches the threshold for automatic shutdown of the boiler equipment, thereby achieving rational use of fuel. |
The hydraulic separator can perform a number of other useful functions.
- First of all, the promised remark about the heating system is not the most ramified type. A hydraulic gun can be useful, and sometimes even mandatory element if the boiler heat exchanger is made of cast iron.
Cast iron heat exchangers do not like sudden temperature changes - they can crack For all its advantages, this metal still has a significant drawback - mechanical and thermal fragility. Sudden temperature change from large amplitude may cause a crack to appear in the cast iron part. Thus, when igniting the heating system in the cold season, a very significant temperature difference can occur - in the firebox and in the return pipe. Warming up the coolant in a large circuit will take a lot of time, and this period is very critical for a cast iron heat exchanger. But if the circuit is “shortened”, that is, run through a hydraulic separator, the coolant will be heated much faster, and the likelihood of deformation of the boiler heat exchanger will be minimal.
Prices for hydraulic separator STOUT
Hydraulic separator STOUT
By the way, some manufacturers of boiler equipment directly indicate the need to install a water gun - violation of these requirements entails termination of the warranty.
- The sharp expansion of volume in the hydraulic needle pipe and the resulting drop in the speed of fluid movement can be additionally “put into service.”
Possible additional functions of the water gun - air separation and purification of coolant from solid suspensions - It is almost impossible to completely eliminate gas formation in the coolant, so Mayevsky drain valves or automatic air vents are installed in the heating system - in the safety group, on heating radiators, etc. Due to its large volume, a hydraulic separator can also become a very effective air separator. To do this, an automatic air vent is installed on top of it (item 1). In addition, on factory-produced models, a special fine-mesh mesh is often installed inside the cylinder, which promotes the active separation of dissolved air from the liquid and its subsequent release through the diverter.
- A sharp slowdown in flow speed promotes gravitational settling of solid suspensions, the appearance of which is quite likely in the coolant. If you install a tap at the bottom (item 2), you will be able to regularly clean the system of accumulated sludge.
Video: Animated demonstration of the functioning of the hydraulic separator
Specifics of the hydraulic separator design
As can be seen from the above, the design of the hydraulic separator is quite simple. However, it must obey certain rules.
You can find many offers on sale in specialized stores, different sizes and configurations, that is, it is possible to select a model that best suits its parameters for the existing or planned heating system. Often found original models, which structurally combine both the hydraulic separator itself and the manifold for connecting the circuits. Sometimes you can see hydraulic arrows and generally unusual star-shaped configurations.
However, if you look at the cost of these products, you will probably think about the possibility self-made. Indeed, for the owner of the house, familiar with plumbing and welding work installing a hydraulic separator should not be difficult. The main thing is to follow the recommended dimensional parameters, which will ensure optimal functionality of the device.
Classic scheme hydraulic separator is based on the “three diameters” rule. What it looks like is shown in the diagram.
“Classical” scheme based on the principle of “three diameters” The diameters, of course, show the internal, conditional passage, regardless of the wall thickness.
Another similar scheme is with pipes alternating in height. Its proportions are shown in the second diagram.
It is believed that the “downward step” for the supply will contribute to better separation of gases, and the “upward step” for the return will more effectively separate suspended solids.
How to calculate the diameter of the hydraulic needle D will be discussed in the next section of the publication. In the meantime, it’s worth noting that this ratio of diameters was not chosen by chance. One of the main goals is to ensure the speed of vertical flows in the range of 0.1 ÷ 0.2 m/s, no more. What is it for:
- The minimum speed ensures maximum cleaning of the coolant from sludge and promotes better air separation.
- At a low speed, the highest quality natural convection of hot, from the supply, and cooled, from the “return” coolant is ensured. This creates a certain temperature gradation in height - a similar property is often used when using a hydraulic arrow as a collector with different temperature pressure - separately for high-temperature (radiators or boiler) and low-temperature (warm floors) circuits. This approach makes it possible to reduce the load on temperature control equipment and increase the overall efficiency of each circuit and the entire system as a whole.
It should be said that the vertical arrangement of the hydraulic needle, although considered “classical,” is by no means a dogma. If we do not take into account the functions of separating air from the coolant and collecting solid suspensions, then, depending on the specific conditions of the location of pipes in the heating system, a horizontal option can be adopted. Moreover, even the location of the supply and return pipes of the boiler and heating circuits can also change. Several examples are presented in the diagram below.
With this arrangement of the hydraulic separator, the requirement to minimize the flow rate in it fades into the background - separation of sediments is not required, and mixing occurs due to the counter-direction of flows from the primary boiler circuit and the heating circuit. This allows the use of smaller diameter pipes in the manufacture. But at the same time, it is necessary to create conditions to ensure high-quality mixing. To do this, the supply and return pipes of each circuit must be separated by a distance of at least four diameters d, and at the same time, for any pipe diameter, this distance cannot be less than 200 mm.
The hydraulic arrow is not always necessarily welded steel structure. You can find many examples where craftsmen make them from copper pipes or even from - such a device will generally cost very little. True, when using plastic temperature regime in the separation system should not exceed a maximum of 70 °C.
You can also come across completely unexpected solutions. For example, a hydraulic separator is made of small diameter pipes, giving it the appearance of a lattice. With this approach, it is quite possible to limit ourselves to polypropylene or even metal-plastic pipesØ 32 mm.
Following the same principle, some craftsmen install several sections of an old unnecessary heating radiator instead of such a grille. Such a device can fully cope with the function of a hydraulic separator. True, it is necessary to take into account that large heat losses. You will have to think about high-quality thermal insulation for such an improvised hydraulic arrow.
Calculation of a standard hydraulic separator
The ready-made hydraulic separators offered for sale are designed for a certain heating system power. But if you decide to independently manufacture this, in principle, simple design, then it is important to calculate the basic parameters - the minimum diameter of the hydraulic needle itself and the diameters of the supply pipes. After this, guided by the diagrams presented above, it will not be difficult to draw up your own drawing.
Below we will present two options for calculating a hydraulic separator of the “classic” vertical type.
Calculation based on the power of the heating system
Exists universal formula describing the dependence of coolant flow on the total need for thermal power, the heat capacity of the coolant and the temperature difference in the supply and return pipes
Q = W / (s × Δt)
Q– consumption, l/hour;
W– heating system power, kW
With– heat capacity of the coolant (for water – 4.19 kJ/kg×°C or 1.164 Wh/kg×°C or 1.16 kW/m³×°C)
Δt– temperature difference between supply and return, °C.
At the same time, the flow rate when the liquid moves through the pipe is equal.
Separators are classified according to a number of parameters:
- Form- round, square.
- Number of circuits- four, six or eight inputs/outputs.
- Tube placement— along one axis/alternating.
- Installation- vertical or horizontal. The first option removes sludge and excess air from the coolant. The second scheme is used when additional filters are available.
Purpose
Hydraulic separator - additional unit that maintains the integrity of the heat exchanger from water hammer. The procedures for initial start-up, technical inspection, and boiler maintenance are accompanied by turning off the circulation pump, contributing to the formation of air pockets.
Arrangement of hydraulic separator — mandatory requirement when installing cast iron heat exchangers, since the temperature difference between the fluid at the outlet and inlet destroys the metal. The hydraulic arrow equalizes the pressure when the flow rate in the main circuit and total indicators consumer pipes.
Cleaning the coolant from rust and scale, extends the service life of moving and rubbing elements highways. For example, pumping equipment, shut-off valves, counter, temperature sensor. Prevents damage to the heating main during automatic blocking of the hot water supply system and the “warm floor” system.
Principle of operation
When the system is first started, cold liquid, driven by the pump, circulates in the pipes and enters the hydraulic valve.
The hot coolant rises up, the cold coolant falls down to the boiler for further heating. Hydroarrow mixes cold and hot liquid flow naturally, collecting excess air and harmful deposits.
How to do it yourself: preparing tools and materials
Self-installation hydraulic arrows require the use of:
- welding machine;
- hammer;
- Bulgarians;
- collector(a profile pipe is enough 80x80 with wall 3 mm);
- two square washers at the ends;
- two threaded elements for air release and drain valve;
- two boiler pipes with thread diameter 25 mm;
- 6 threaded parts 20 mm each for consumers ( 2 for heating, 2 for underfloor heating, 2 for indirect heating);
- pressure gauge;
- cranes;
- bimetallic crowns 25 and 29 diameter, drills 8.5 mm;
- welding electrodes (3 mm);
- primers, hammer paints.
Attention! Necessarily check the quality of the connecting parts. By installing crooked threads, taps and pumps will be damaged.
Preliminary calculations
To create drawings of hydraulic guns it is necessary to correctly determine the diameter of the pipe.
Photo 1. Metal hydraulic arrow installed in the heating system. Before installation, it is necessary to calculate the diameter of the pipes.
Calculations are carried out according to the formula: D=49*√W: Δt, Where:
W— power of boiler equipment.
Δt- temperature difference.
The length of the collector must correspond to six diameters, and the distance between the tubes is equal to 2-3 Ø. Using the data obtained, diagrams of the device assembly are drawn.
Manufacturing sequence, diagram
In a pre-prepared collector, holes are burned with an electrode, according to the markings. For 3 consumers use profile pipe length 900 mm. A chamfer is made on the end surface of the bends approximately 1 mm. Mark the location of the collector pipes: on one side 3 feeds, 3 returns. Retreat along 50 mm from the edge of the “cold” and “hot” sides, move away 150 mm each for 3 pipe inlets.
On the opposite wall of the pipe, a hole is drilled for the supply circuit (opposite the middle outlet for consumers). From this hole measure 250 mm, drill an additional gap for the return line. The resulting design provides for placement 6 pipe entries consumers on the one hand, 2 holes for boiler contours from the opposite.
To create the initial holes, use a step drill. Achieve the required diameter for the thread entry ¾ a crown will help 20 mm. Additional nozzle (diameter 29 mm) create inch holes for the boiler circuit.
Photo 2. Diagram of a hydraulic switch for the heating system. The pipes into which the hot water circuit is connected are indicated in red, and the cold ones in blue.
Square washers serve as plugs. Steel couplings are welded to the plates. The ends are cleaned, a bevel is made on the edges, and they are secured to the separator with a welding machine. The first seam is formed, cleaned, and additional lining is carried out by welding.
Threads for the boiler circuit and consumer pipes are welded onto the cleaned hydraulic needle. Having screwed on the cast iron plugs, prepare the device for testing. Pumping equipment that pumps up water is connected. Control the working pressure ( 2 atmospheres) through the drain valve fitting. All that remains is to prepare the hydraulic arrow for painting, having previously protected the threads from finishing material.
Install the device vertically, horizontally, at an angle. The air valve is placed at the top, the drain valve is at the bottom. Complex structures are equipped with horizontal partitions. A sludge collector and a magnetic catcher are placed at the bottom of the housing. Aeration occurs at the top.
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Boiler connection
The hydraulic distributor is connected to the boiler through supply and return pipes.
Hot water rises through the upper tube and is divided between consumer circuits. The cooled fluid flows back to the lower hydraulic distributor tube.
Using a combless system, the number of tie-ins into the hydraulic arrow will increase. The pipe connecting the first boiler circuit to the separator is distributed in height.
Fulfilling the condition helps improve the quality of liquid selection by secondary outlets.
Collector functions
The collector is installed in a network using more than 3 radiators. Tubes for draining water to consumers are connected to the comb. Falling ones are at the top, return ones are at the bottom. Hot water from the boiler moves through the upper pipe, cold water through the lower circuit. The heat exchanger is located on the side, on the reverse side of the hydraulic arrow. The scheme provides presence of balancing valves between the supply/return manifold. Control valves increase the flow rate and pressure on circuits farthest from the separator.
Installation of shut-off valves
Receiving a fast flow of coolant, the hydraulic arrow slows down the movement of water. The air released in the liquid accumulates at the top where it is installed air vent.
The shut-off valve of the device allows you to replace the automation in emergency situation, maintaining the operating condition of the heating network.
An alternative to automatic air vents will be Mayevsky crane, requiring periodic unscrewing to remove mechanical deposits.
Do-it-yourself installation of a polypropylene hydraulic arrow
Having decided to create a polypropylene separator yourself, all you need to do is prepare a hollow round pipe equipped with pipes for connecting the heating network. The supply circuits are usually located at the top, the return circuits at the bottom. The tees are connected to each other by pipe sections, and the ends are closed with plugs. The work is carried out using a welding machine with nozzles.
Connecting a wall-mounted boiler to maximum power 40 kW, it is preferable to use a ring collector for 2-4 circuits. The collector and hydraulic switch operate in one housing, devoid of internal partitions. The coolant constantly circulates through the boiler and collector. Heat is removed from the plastic comb by a pumping group. The simplified design of the PVC buffer will take up minimal space and costs.
Photo 3. Hydraulic arrow made of polypropylene. A hot coolant circuit is connected to the upper part of the structure. in the bottom - with cold.
Pros and cons of polypropylene products
Polypropylene separators will provide Main advantages systems:
- Smooth surface material will reduce the coolant resistance, reducing heat losses of the boiler.
- Polypropylene convenient to paint outside with heat-resistant paint.
- Price plastic construction costs cheaper analogs.
- Plastic products prevent the formation of corrosion.
- Work effectively with boilers with power up to 35 kW.
- Adjust pressure in system.
- Automatically distribute thermal flows in the required direction.
- Smoothes water hammer.
- Increases boiler efficiency, fuel economy.
Flaws polypropylene separators:
- Inability to install hydraulic guns in a system with solid fuel boiler . Polypropylene is subject to rapid wear when high blood pressure, temperature.
- Installation of the structure uses additional equipment (welding machine for polypropylene), couplings, bends, taps.
- Hydraulic needle diameter must correspond to the three circumferences of the pipes contours ( 60—90, 120 mm). Pipes of the required sizes are rare and expensive.
Important! Solid fuel boilers water is heated frequently up to 90-95 °C. Polypropylene can withstand temperature loads, but in case of an emergency (during a power outage), the supply coolant warms up up to 130 °C.
Useful video
Watch the video that explains the design and operating principles of the hydraulic gun.
Hydraulic separators are often equipped with pressure gauges and temperature sensors, necessary for complex heating systems. When planning heating with one or two radiators, many craftsmen neglect installing automation.