Thermal arrow working principle. A water gun for heating: we understand why it is needed and how it works

Water heating system Is a unit that constantly and efficiently heats rooms both in a small apartment and in a residential neighborhood of the city.

For this unit to work properly with maximum efficiency, it is necessary to maintain in different parts of this system the pressure, temperature and flow rate of the coolant within optimal limits.

The larger and more complex this system, the more difficult it is to maintain a balance of parameters in it. A simple detail helps to solve the problem of water heating control - hydro arrow.

The water gun is called vertical metal vessel installed between the boiler and the rest of the heating system.

This part has many synonyms: bottle, hydraulic separator, hydraulic valve, hydraulic manifold, etc.

As a rule, a hydraulic separator is connected to the system four branch pipes... On the one hand, the direct and return pipes of the boiler are connected to them, and on the other, the supply and return pipes of the heating system.

In large houses with a large number of radiators, instead of the supply and return pipes, they attach to the hydraulic switch supply and return manifold, with the help of which there is a distribution and collection of coolant flows.

Several parallel boilers are sometimes connected to the heating unit through a hydraulic valve. In this case, the number of nozzles increases.

Some manufacturers of heating equipment necessarily include in the set of parts for installation hydraulic valve... This part is included not only in standard kits for units of a certain power, but can also be calculated for a heating system on a special order.

The principle of operation of the hydraulic arrow

At start-up, reaching the set mode and turning off the heating in the hot water heating system, various emergency situations.

One of them is called heatstroke... After starting the boiler, the coolant heats up and enters the batteries.

However, the batteries are filled with cold coolant, which is displaced from them and enters the already heated boiler. Abrupt and uneven cooling of the boiler heat exchanger pipes leads to their deformation.

Cast iron heat exchangers are very fragile and especially sensitive to rapid uneven heating. When starting heating without a hydraulic separator, they often crack and fail.

Probability of failure heating equipment increases significantly if:

the system is quickly started at the beginning of the season at low temperatures or after a shutdown and urgent repairs;
for any reason, the pumps are turned off;
some of the contours are covered.

A multi-circuit heating unit suffers from one significant disadvantage: in the event of overlap of part of the circuits, the pressure and flow rate in the operating circuits increase, which can lead to overheating and damage.

Important: a hydraulic arrow in a multi-circuit heating system excludes sharp fluctuations in pressure and flow rate, and, consequently, negative mutual influence of the circuits.

In addition to the main function of regulating pressure and flow rate, a hydraulic separator collects air bubbles and mechanical impurities migrating through the pipes. Air is removed from the system through a valve at the top, and sludge is removed through a valve at the bottom of the hydraulic switch.

Thanks to this cleansing function metal oxidation slows down at the points of contact with the coolant, which increases the service life and reduces the likelihood of breakage of such parts:

batteries;
shut-off and control valves (taps, gate valves, bypass valves, etc.);
pumps;
heat exchangers.

Heating at the beginning of the season starts at a temperature from +5 to + 15 ° С... After the installation or repair is completed and the system is filled with coolant, the boiler is started and the circulation pump is turned on.

Heated about up to + 60 ° С the liquid enters the batteries, and instead of it, water with a temperature of about + 10 ° C is supplied to the boiler. There is a risk of heat shock and destruction of boiler parts.

If a hydraulic arrow is mounted between the boiler and the collectors, part of the hot coolant flow is not sent to the radiators, but is mixed with the cold one and returns to heating. Thus, the temperature difference of the coolant between the supply and return pipelines decreases and danger of destruction of the boiler liquidated.

After heating the liquid in the entire system, most of it enters the radiators. Further, the hydraulic valve acts as a water purifier from air and sludge. However, the role of the hydraulic arrow is not limited to these functions.

The unit operates in different modes depending on the outside air temperature. During a thaw, the heating demand decreases. Thermal radiator heads reduce the clearance or shut off the coolant flow completely.

Hydraulic resistance the system grows, therefore the main flow of the coolant is directed not to the batteries, but through the hydraulic arrow to the boiler. The boiler automation turns off the heating, and the water circulates through the hydraulic valve.

When the temperature in the rooms falls below normal, the thermal heads open the valves, allowing the flow to the batteries, and the automation turns on the heating again.

Important: gidrostrelka constantly takes part in the redistribution of flows and smooths out the temperature difference in the heating system.

Calculation methods

For a heating system of a certain power, you can pick up in the store a suitable set of parts. The hydraulic valve is included in such a set, and it is not necessary to calculate its parameters.

But with self-installation you need calculate the size of the hydraulic arrow before manufacturing so that the heating unit operates at maximum efficiency.

Exists two ways of calculating:

method of three diameters;

method of alternating pipes.

The first way implemented by the formula:

where D is the inner diameter of the hydraulic arrow, mm;

d is the inner diameter of the branch pipes, mm;

P is the boiler power in kW;

с - heat capacity of water (4183 J / kg · deg);

W is the speed of movement of the coolant through the diameter of the hydraulic arrow (0.2 m / s is recommended);

ΔT is the temperature difference between supply and return.

As you can see, the diameter of the hydraulic separator is equal to the threefold diameter of any of the branch pipes. There is also relationship between the pump flow and the diameter of the delivery pipe:

where D is the diameter of the supply pipe in mm;

Q is the pump flow rate in m³ / s;

A hot water heating system for a 200 m² house and more necessary you need to turn on the hydraulic arrow. Units of lower power, designed for a smaller area, can be equipped with this device at will. In any case, the performance of the heating system is improved.

The hydraulic valve can be purchased as a set. For complex and powerful systems, you have to do individual calculation this appliance. The calculation is done according to a special program.

How the low loss header works, see the video below:

The scheme of operation of the heating system with a hydraulic arrow, why is it needed and what they are, learn from the video:

A hydraulic arrow (low loss header, hydraulic arrow) is a heating system element that allows different heating circuits to be connected to each other. The separator maintains a minimum pressure drop between the circuits, which allows one or more circuits to be shut off without changing the pressure in the other circuits. In other words, the water gun for heating excludes 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 low loss header is used in branched heating systems where there are several circuits.

Why use a hydraulic arrow?

Section of the heating system with a hydraulic arrow.

In heating systems where there are two or more heating circuits (radiators, underfloor heating, hot water supply), as a rule, the circuits are interconnected by a common collector. At the same time, the presence of a common collector can lead to the following problems:

The circulating pumps of each of the circuits influence each other (especially if the pumps differ in power). To overcome the impact of a more powerful pump, a low-power pump must operate at its maximum capacity, consuming more electricity than is required under "normal" conditions. At the same time, working at the limit of their capabilities, the pumps fail earlier. In addition, in such conditions, the pump cannot always provide the required performance;

A water gun for heating why is it needed?

Even if the circulation pump of one of the circuits was turned off, its radiators will still heat up (under the influence of other pumps, the circulation of the coolant in the disconnected circuit will be maintained);
Difficulties in calculating the pump power for both the boiler and heating circuits. The power of the boiler pump must be selected taking into account the total power of the heat consumers' 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 at the entrance to the separator, the flow diameter increases several times (as a rule, 3 times). This eliminates pressure drops in the system.

Design, purpose and principle of operation of the hydraulic switch

The water gun for heating consists of a bronze or steel body with two nozzles for connecting to the boiler circuit (supply pipe + return pipe), as well as several nozzles (usually 2) for connecting heat consumer circuits. In the upper part of the low loss header through a ball valve or mounted, in the lower part a drain (drain) valve. A special mesh is often installed inside the body of factory hydraulic shooters, which allows you to direct small air bubbles into the air vent.

The hydraulic arrow for heating has the following functions:

Maintaining the hydraulic balance of the system. Enabling / disabling 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 allows you to protect cast-iron heat exchangers from sudden temperature changes (for example, during repair work, when the circulation pump is turned off, or when the boiler is turned on for the first time). As you know, a sharp change in the temperature of the coolant has a negative effect on cast-iron heat exchangers;
Air vent. The water gun for heating performs the function of removing air from the heating system. For this, in the upper part of the device there is a branch pipe for mounting an automatic air vent;
Filling or draining the heating medium. Most of both factory and self-made hydraulic switches are equipped with drain taps, through which it is possible to fill or drain the coolant from the system;
Cleaning the system from mechanical impurities. The low flow rate of the coolant in the hydraulic separator makes it an ideal device for collecting various mechanical impurities (scale, scale, rust, sand, etc. sludge). The solids circulating through the heating system gradually accumulate at the bottom of the device, after which they can be removed through the drain cock. Some models of hydraulic arms 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:

We turn off the boiler and circulation pumps;
After the coolant has cooled down, we shut off the section of the pipeline where the drain valve is located;
We put on a hose of a suitable diameter on the drain valve, or, if space permits, we substitute a bucket or any other container;
We open the tap, drain the coolant until clean water comes out without contamination;
We close the drain valve, after which we 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 required to achieve maximum coordination, balancing the work of all its elements. It is not so easy to achieve such "harmony", especially if the system is complex, branched, including several circuits that differ both in the principle of operation and in the temperature regime. In addition, heating circuits, individual heat exchange devices can have their own devices for automatic regulation and operation, which, by their intervention, should not affect the functionality of the "neighbors".

There are several approaches to achieving such a "unison", but one of the simplest and most 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 is this element, what is the principle of its operation, how to calculate and mount it correctly - in this publication.

What is a low loss header in a heating system for?

To understand the purpose of the hydraulic arrow, let's remember how it works in general.

In the simplest version, a system with forced circulation can be represented as follows.

The diagram is shown with great simplification. So, it does not show the expansion tank and elements of the safety group, simply for reasons of "lightening" the picture.

K - boiler, provides heating of the coolant.

N1 is a circulation pump, thanks to which the coolant moves through the supply pipes (red lines) and "return" (blue lines). 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 (RO) are embedded on the closed circuit of the pipes, providing heat exchange - the thermal energy of the coolant is transferred to the premises of the house.

With the correct selection of the circulation pump in terms of performance and the created pressure in the simplest single-circuit heating system, it can be quite enough in a single copy, and there seems to be no special need to install additional devices. There will be a comment on this - a little later.

Circulation pump - 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 of our portal.

For a small house, such a simple scheme may be sufficient. But in a larger building, it is often necessary to use several heating circuits. Let's complicate the scheme.

Can one pump handle multiple circuits? Far from being a fact ...

This figure shows that the pump provides 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 (PO).

- (VTP), for which the temperature of the coolant should already be significantly lower, which means that special thermostatic devices will be involved. The sensory length of the underfloor heating contours is also usually several times larger than the usual radiator wiring.

- The system for providing the house with hot water with the installation of an indirect heating boiler (BKN). Here, there are very special requirements for the circulation of the coolant, since usually the temperature of hot water heating is regulated by changing the flow rate of the coolant flowing through the boiler.

Will our only pump cope with such a load, with such a flow rate of the coolant? Probably not. Of course, there are models of high productivity and power, with large indicators of the created pressure, but the possibilities of the boiler itself are not unlimited. Its heat exchanger and internal nozzles are designed for a certain capacity and generated pressure, 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 works constantly at the peak of its capabilities, providing all the circuits of the branched system with a coolant, is unlikely to last long. This is not to mention even the increased noise of powerful equipment and considerable energy consumption.

What is the way out - to install on each circuit its own circulation pump, calculated according to the parameters of its "subsystem", which it serves.

So, each of the circuits has its own pump. Has the problem been resolved? Alas, this is far from the case - it just passed into "another plane" and even worsened!

As a result, this often leads to unacceptable overheating of warm floors, to uneven heating of various rooms, to "locking" of the circuits and to other negative phenomena that negate the efforts of the owners to create a highly efficient system.

And the worst thing in this case is the pump installed near the boiler - all the instability of the system parameters is primarily reflected in its operation, and ultimately - in the "torn apart", not amenable to precise adjustments of the boiler functioning. But often in large houses two or more boilers are installed in cascade - managing such a system becomes generally an extremely difficult, almost impossible task. All this causes rapid wear of expensive equipment.

And the way out, it turns out, is quite simple - it is necessary to divide the entire hydraulic system not only into end-use circuits, through the collector, but also to separate a separate boiler circuit.

It is this function that the hydraulic arrow (HS) performs. This simple device is installed between the boiler and the collector.

The correct full name of the hydraulic arrow is a hydraulic separator. It was called the arrow, most likely, because it is able to redirect the hydraulic flows of the coolant, ensuring the balance of the entire system as a whole.

The construction of a conventional hydraulic arrow is extremely simple

Structurally, this element is a hollow pipe of round or rectangular cross-section, plugged at both ends, with two pairs of branch pipes - outlet for supply, and inlet - for the "return" pipe.

In fact, two interconnected, but, in fact, independent of each circuit are formed: a small boiler contour and a large one, which includes a collector with all the branches to the other circuits. Each of these two circuits has its own flow rate and speed of movement of the coolant, which do not have any significant effect on each other. Usually the Q1 indicator is a stable value, since the boiler pump works constantly at the same speed, Q2 is changing in the course of the current operation of the heating system.

In fact, 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 that a section of low hydraulic resistance is created, which makes it possible to equalize the pressure in a small circuit, to supply it regardless of the work or downtime of the working circuits. In general, this leads to a balanced operation of each of the sections of the heating system, to a smooth, not subject to pressure and temperature surges, the functioning of the boiler equipment and the entire system as a whole.

How does a low loss header work

In principle, three modes of operation of the low loss header are possible.

Illustration	Description of the operating mode of the hydraulic arrow
	This is an almost ideal, equilibrium state of the system. The head created by the small boiler circuit pump is equal to the total head of all heating circuits (Q1 = Q2). The temperature at the inlet and outlet of the supply are equal (t1 = t3). A similar situation is with the "return" pipes (t2 = t4). The vertical movement of the coolant is minimal or even completely absent. In practice, if such a situation occurs, it is extremely rare, episodically, since the operating parameters of the heating circuits tend to change periodically.
	Situation two. The total flow rate of the heating agent in the heating circuits exceeds the same indicator of the boiler pump (Q1. In essence, it can be characterized in such a way that the “demand” for water exceeds what the boiler can “offer”. The situation is quite common when most of the circuits are simultaneously involved. 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 is mixed with the hot coolant coming from the boiler. Temperature range: t1> t3, t2 = t4.
	The situation is diametrically opposite - the flow rate in a small circuit (without changing nominally) has become higher than in total in the heating circuits (Q1> Q2). The “supply” exceeded the “demand” for the heat carrier. Typical reasons for this situation: - actuation of thermostatic equipment on heating circuits or on an indirect heating boiler, which temporarily turns off the supply of the heat carrier. - temporary complete shutdown of one or more circuits due to the lack of demand for heating certain premises. - temporary decommissioning of circuits for repair or maintenance work. - start-up of boiler equipment for heating, with a gradual stepwise connection of working circuits. Nothing critical happens - the boiler circuit works for the most part "for itself", pumping the main volume of the coolant in a small circle. In the hydraulic arrow itself, a vertical downward flow is formed, from the supply to the "return". Temperature range: t1 = t3, t2> t4. With this operating mode, the temperature in the "return" rather quickly reaches the threshold for the automatic shutdown of the boiler equipment, which achieves rational use of fuel.

The low loss header can perform a number of other useful functions.

First of all - the promised remark about the heating system is not the most branched type. A hydraulic arrow can become a useful, and sometimes even an indispensable 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 disadvantage - mechanical and thermal fragility. A sharp temperature drop with a large amplitude can lead to the appearance of a crack 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. Heating up the coolant in a large loop 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 heating medium will be heated much faster, and the probability of deformation of the boiler heat exchanger will be minimal.

Prices for a low loss header STOUT

Low loss header STOUT

By the way, some manufacturers of boiler equipment directly indicate the need to install a hydraulic arrow - violation of these requirements entails the termination of warranty obligations.

The sharp expansion of the volume in the pipe of the hydraulic arrow and the resulting drop in the speed of movement of the liquid can be additionally “put to service”.

Possible additional functions of the hydraulic arrow - air separation and cleaning the coolant from solid suspensions

It is almost impossible to completely eliminate gas formation in the coolant, therefore Mayevsky's drain valves or automatic air vents are installed in the heating system - in the security group, on heating radiators, etc. Due to its large volume, the hydraulic separator can also become a very effective air separator. To do this, an automatic air vent (pos. 1) is cut into it from above. In addition, on factory-made models, a special fine-mesh mesh is often installed inside the cylinder, which contributes to the active separation of dissolved air from the liquid, followed by its release through a drain.
A sharp deceleration of the flow rate contributes to the gravitational settling of solid suspensions, the appearance of which is quite likely in the coolant. If you install a tap (pos. 2) from below, it will be possible to regularly clean the system from accumulated sludge.

Video: Animated demonstration of the operation of the low loss header

Specific design of the low loss header

As can be seen from the above, the design of the hydraulic separator is rather straightforward. However, she must obey certain rules.

On sale in specialized stores you can find many offers, of different sizes and configurations, that is, it is possible to choose a model that is most suitable in terms of its parameters for the existing or planned heating system. Often there are original models that structurally combine both the hydraulic separator itself and the manifold for connecting the circuits. Sometimes you can see water arrows and, in general, an unusual star-shaped configuration.

However, if you look at the cost of these products, you will surely have an idea of the possibility of self-production. Indeed, for the owner of the house, who is familiar with plumbing and welding, it should not be difficult to mount a hydraulic separator. The main thing is to comply with the recommended dimensional parameters that will ensure optimal functionality of the device.

The classic low loss header design is based on the “three diameters” rule. How it looks is shown in the diagram.

"Classic" scheme according to the principle of "three diameters"

The diameters, of course, show the internal, nominal bore, regardless of wall thickness.

Another similar scheme is with nozzles alternating in height. Its proportions are shown in the second diagram.

It is believed that a "step down" for the feed will facilitate better gas separation, and a "step up" on the return line will more effectively separate suspended solids.

How to calculate the diameter of the hydraulic arrow D - will be described in the next section of the publication. In the meantime, it is worth noting that such a 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, contributes to better air separation.
At a low speed, the highest quality natural convection of hot, from the supply, and cooled, from the "return" heat carrier is provided. 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 head - separately for high-temperature (radiators or boiler) and low-temperature ("warm floors") circuits. This approach allows to reduce the load on thermostatic equipment, to increase the overall efficiency of each of the circuits and the entire system as a whole.

It should be said that the vertical arrangement of the hydraulic arrow, although it is considered "classic", is by no means a dogma. If we do not take into account the function 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 also be adopted. Moreover, even the location of the supply and return pipes of the boiler and heating circuits can also change. Several examples are shown in the diagram below.

With such an arrangement of the hydraulic separator, the requirement to minimize the flow rate in it goes into the background - no sediment separation is required, and mixing occurs due to the opposite direction of flows from the primary boiler circuit and the heating circuit. This allows you to use in the manufacture of pipes of a smaller diameter. But at the same time, it is necessary to create conditions to ensure high-quality mixing. For this, the supply and return nozzles of each of their circuits must be spaced at a distance of at least four diameters d, and at the same time, for any diameter of the nozzle, this distance cannot be less than 200 mm.

The water gun is not necessarily always a welded steel structure. You can find many examples when craftsmen make them from copper pipes or even from - such a device will generally cost quite inexpensively. True, when using plastic, the temperature regime in the separation system should not exceed the maximum 70 ° C.

You can also come across completely unexpected solutions. So, for example, a low-loss header is made of pipes of small diameter, giving it the appearance of a lattice. With this approach, it is quite possible to restrict ourselves to polypropylene or even metal-plastic pipes Ø 32 mm.

Following the same principle, some craftsmen install several sections of an old unnecessary heating radiator instead of such a grill. Such a device will fully cope with the function of a low loss separator. True, it is necessary to take into account the fact that large heat losses are inevitable. We'll have to think about high-quality thermal insulation of such an impromptu hydraulic arrow.

Calculation of a standard low loss header

The ready-made low loss header offered for sale is designed for a specific heating system power. But if a decision is made to independently make this, in principle, simple structure, then it is important to calculate the basic parameters - the minimum diameter of the hydraulic arrow itself and the diameters of the supply pipes. After that, guided by the diagrams presented above, it will be easy to draw up your own drawing.

Below will be presented two options for calculating the hydraulic separator "classic" vertical type.

Calculation based on the power of the heating system

There is a universal formula describing the dependence of the flow rate of the coolant on the total demand for heat power, 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 heat carrier (for water - 4.19 kJ / kg × ° С or 1.164 W × h / kg × ° С or 1.16 kW / m³ × ° С)

Δt- temperature difference between supply and return, ° С.

At the same time, the flow rate when the fluid moves through the pipe is equal.

So, what is called a water gun in the heating system of a private house? The temperature and hydraulic buffer, which provides the processes of correlation of return and supply temperatures, an ordered maximum flow of the coolant, is called a hydraulic arrow. What is a hydraulic arrow for?

It is very simple to explain why a hydraulic arrow is needed in the heating system? The owners of private houses are well aware of what an imbalance in heat supply is. Modern boilers have a smaller circuit. At the same time, the consumption of the consumer during circulation is less. With the help of a hydraulic arrow, you can separate its operation from the heat generator of the secondary circuit, increase the reliability and quality of the system.

Hydraulic separator in the heating system

To understand why a hydraulic arrow is needed in a heating system, it is necessary to name a number of advantages of heating systems with a hydraulic thermal separator. First of all, the separator is a prerequisite for equipment manufacturers to guarantee maintenance for a boiler with a capacity of up to 50 kilowatts and more. With the help of an auxiliary unit, the maximum flow with a laminar flow of the coolant is ensured. The temperature and hydraulic balance in the heating system is constantly maintained. The water gun and the heating circuit are connected in parallel. This creates minimal losses in pressure, performance and heat. The supply and return pipes are located according to the knee principle. This provides a temperature gradient for the secondary circuits. If you choose the optimal hydraulic arrow for heating, then you can protect the boiler from the difference in flow and return temperatures.

The equipment is protected from thermal shock. The hydraulic arrow increases the efficiency of the boiler. In addition, a secondary circulation of a part of the coolant in the boiler circuit is ensured. Fuel and electricity are saved. The boiler water volume is kept constant. If necessary, it is possible to compensate for the flow deficit in the secondary circuit using a separator. If the pumps are of high power, their influence can be reduced by means of a hollow divider. The load is applied to the secondary circuit and the boiler.

Hydrodynamic processes in the system are stabilized by the principle of operation of a hydraulic arrow. In order to extend the life of the pump, it is necessary to promptly remove mechanical impurities from the coolant. In addition, the service life of sensors, meters, valves is extended. When dividing flows (independent consumer circuit and heat generator circuit), the hydraulic arrow ensures maximum use of the fuel combustion heat.

Video: What is a hydraulic arrow (hydraulic arrow)

Hydraulic arrow for heating systems, diagram and how it works

The low loss header is a vertical hollow vessel that consists of large diameter (square profile) pipes with elliptical end caps. The dimensions of the separator are determined by the power of the boiler and depend on the number and volume of the circuit.

The hydraulic arrow has a massive metal body. It is installed on supports so that there is no line voltage on the pipeline. Compact units are mounted to the wall with a bracket. The heating pipeline and the branch pipe of the hydraulic arrow are connected using flanges or threads.

Low loss header device

An automatic air vent valve is installed at the top of the body. The sediment can be removed through a special valve or valve. It is cut from below. As a rule, the hydraulic pointer is made of mild steel or stainless steel, copper, and polypropylene. The body will be treated with an anti-corrosion compound and covered with insulation.

Important! Polymer hydraulic arrows are used in systems that are powered by a 13-35 kilowatt boiler. For heat generators that run on solid fuels, polypropylene hydraulic arrows are NOT used.

Additional parameters of the heating system equipment

Modern models, as a rule, are combined with the function of a separator, temperature controller and separator. The thermostat valve provides a temperature gradient on the secondary circuit. The release of dissolved oxygen from the coolant reduces the risk of erosion of the internal surfaces of the equipment. Removing suspended particles from the flow will help to extend the life of the wheel and bearings of circulation pumps.

Perforated horizontal partitions divide the internal volume in half. The flow return flows are connected in the zero point zone, slide in different directions, while no additional resistance is created.

Hydraulic separator connection and operating principle

The high-temperature zone contains porous vertical deaeration plates. The sludge collector and magnetic trap are located in the lower part of the housing.

Gidrostrelka has some design features. So, it has a temperature sensor, a pressure gauge, a thermostat and a valve, as well as a line for powering the system when it is turned on. Complex equipment requires adjustment, frequent inspections, maintenance.
The operation of the hydraulic arrow in the heating system

In the coolant, the flow passes at a speed of 0.2 meters per second. The boiler pump accelerates boiling water to 0.9 meters per second. From the recommended speed limit, you can understand what the hydraulic switch is intended for.

By changing the direction of flow, the speed of water flows is extinguished with minimal heat loss in the system. Laminar flow results in almost no hydraulic resistance in the housing. The buffer zone divides the boiler into a consumer circuit. Autonomous operation of the pump on each heating circuit is ensured. The hydraulic balance is not disturbed.

The design parameters of the system correspond to the neutral operating mode of the hydraulic separator, at which such parameters as pressure, temperature and flow rate correspond. The pumping equipment has sufficient total capacity. Suspended particles are deposited in a hydraulic gun by means of laminar flow movement.

Low loss header: operating principle in heating a private house

The principle of operation of the hydraulic arrow is reflected. At the same time, the boiler does not have enough power to provide the flow in the secondary circuit. Thermal sensors are triggered when there is a difference in flow-return temperatures. When there is a shortage of flow, cold water (heat carrier) is mixed in. Automatic equipment brings the heat generator to the maximum combustion mode. But the consumer is not getting enough heat. If the heating system is out of balance, there is a threat of heatstroke.

Hydraulic arrow for heating systems, operation diagram

On the primary circuit, the volumetric flow is greater than the flow rate of the heating medium of the dependent circuit. If the boiler is operating in optimal mode, then when the unit is fired up or when the pumps of the secondary circuits are switched off in parallel, the coolant circulates through the hydraulic arrow along the primary circuit. The return temperature entering the boiler is leveled by adding coolant from the supply. The consumer receives a sufficient amount of heat carrier.

It is considered mandatory that the manufacturer, who has a circulation pump in the primary circuit, is 10 percent more than the total head of the pumps in the secondary circuit.

How to calculate the parameters of a hydraulic arrow in a home heating system

Remarkable! Formulas for calculating a water arrow for heating are obtained empirically. The diameter of the inlet pipe to the hydraulic separator corresponds to the diameter of the boiler outlet.

For example, if you determine the parameters of the hydraulic arrow by a practical method, then the approximate size for small dividers should be selected according to the diameter of the outlet nozzles. The distance between the inserts is at least 10 choke diameters. The height of the body will be much larger than the diameter of the pipes.

The cranked circuit of the hydraulic arrow for heating is used in the selection of a large-sized installation. According to the 3D rule, the diameter of the body will be three diameters of the nozzle. The 3D distance is determined by the proportions of the structure.

If the system does not have a manifold, then the number of tie-ins into the separator will be greater. The piping that connects the primary circuit with the hydraulic switch is distributed in height. This method makes it possible to regulate the temperature gradient over time. The condition must be met for a high-quality selection of the coolant by the secondary circuits. A boiler is needed to heat small houses. A pump is built into it. The secondary circuits are connected to the boiler by means of a hydraulic switch. Independent circuits in residential buildings with a large area are connected via a comb. In this case, the low loss header will be large. The distribution manifold is installed after the hydraulic switch. The device consists of two independent parts. They are connected by jumpers. According to the number of secondary circuits, the pipes located in pairs are cut in.

Appearance of the hydraulic separator

Due to the distributor comb, the operation and repair of equipment is facilitated. The control and shut-off valves of the heat supply system of the house are located in one place. The increased diameter of the manifold creates an even flow between the different circuits.
The coplanar manifold and splitter form a hydraulic module in a complex. The compact unit is convenient for boiler rooms that do not have a large area.
Mounting studs are created to be strapped with an asterisk. The low pressure floor heating circuit is connected from below. The high-pressure radiator circuit is connected to the system from the top.
The heat exchanger is installed on the side, on the opposite side from the hydraulic switch.

With the help of control valves, the maximum flow is ensured, as well as the pressure on the circuits farthest from the hydraulic switch. By balancing, the processes of incorrectly throttled flow are reduced. This makes it possible to obtain the calculated supply of the coolant.

Important! An autonomous heating system is a circuit that operates with a high temperature of the medium under pressure.

In order to make a hydraulic arrow in the heating system of a private house, you need to have special skills. In addition, you need to have certain knowledge in heating technology. Today there are many sites that provide step-by-step instructions on how to create a hydraulic arrow for a heating system with your own hands.

A hydraulic arrow or a low loss header for a heating system are devices for equalizing temperatures and pressures in the system. Installed before and after the boiler to ensure smooth and soft balancing of the heating system. Usually, this device is bought ready-made, but a hydro-arrow can be made for heating with your own hands. The Santechnik Portal website provides a working scheme for the manufacture of a thermohydraulic distributor.

Hydraulic arrow - it is also a hydraulic divider, a thermohydraulic valve, a hydraulic separator, a bottle, a hydraulic valve, a hydraulic arrow. All these are the names of the same boiler piping device.

Before studying the circuit and making a hydraulic arrow, you need to find out why it is needed, what tasks it performs.

When designing an independent heating system, one of the main difficulties is constantly accurate balancing of its functioning. It is necessary to ensure that all equipment and areas are working correctly. Each element fully coped with its tasks, but at the same time did not have a negative impact on other nodes.

It is very difficult to do this, especially with a complex, branched system with several circuits, since usually each circuit has its own thermostatic control circuit, its own temperature gradient, its own flow capacity and the required level of coolant pressure.

To connect all the elements into a single system, a hydraulic arrow is used for heating systems. This device balances the performance of all components.

As a rule, a thermohydraulic valve works with a forced circulation system, where each circuit has its own circulation pump. In order for all circuits to work correctly, it is necessary to ensure the most accurate coordination of all circulation pumps. The hydraulic separator perfectly copes with this task.

In addition, the thermo-hydraulic valve is capable of performing several other useful functions:

at the bottom of the hydraulic arrow there is a valve for periodically draining accumulated suspensions and sediments from the system;
ensuring the maximum flow of the coolant, maintaining the hydraulic and temperature balances;
provides minimal loss of pressure, productivity and heat energy;
protection of the boiler from the difference in flow-return temperatures and thermal shock;
equalization of the circulating volume of fluid in the primary and secondary circuits;
increasing the boiler efficiency;
the possibility of secondary circulation of part of the coolant in the boiler circuit;
saving electricity and fuel;
preservation of a constant volume of boiler water, thanks to the admixture;
compensation of flow deficit in the secondary circuit;
reducing the effect of pumps with different kW power on the secondary circuits and the boiler;
creating conditions for the separation of dissolved gases and sludge.

Another important function is performed by a hydraulic arrow in systems with a boiler from a cast-iron heat exchanger. Cast iron does not tolerate mechanical and thermal shocks well. As a result of the sudden temperature drop, the heat exchanger may crack. To minimize temperature differences, a low loss header is used.

Thermohydraulic distributor device

The structure of a standard hydraulic valve is very simple. It is a medium-sized round or rectangular tank, plugged from the ends, into which pairs of nozzles are embedded - for connection to the boiler and separately - to the boiler or collector. As a rule, there are four working branch pipes.

In fact, two completely independent contours are formed. They are interconnected in terms of heat transfer, however, the circulation of the coolant in each of them uses its own. In other words, both the flow rate (Q) of the coolant and the created head (N) in each circuit are different. Basically, the performance parameters in the circuit are stable (Qc) - the circulation pump operates in a predetermined suitable mode.

The cross-section of the distributor itself guarantees a minimum hydraulic resistance in the "small" circuit, which makes the circulation in it absolutely independent of the processes currently taking place in the rest of the heating system. A similar principle of boiler operation, without pressure drops, without multiple frequent start-up and shutdown cycles, is the key to its long-term trouble-free operation.

There are also special hydraulic dividers for combining two or more boilers, however, the principle of operation is the same for all devices.

The principle of operation of the hydraulic valve

Without taking into account the various intermediate options, the principle of operation of the hydraulic arrow can be described by three main modes of its operation:

Mode one... The system functions almost in equilibrium. The flow rate of the "small" circuit is almost the same as the total flow rate of all circuits (Qк = Qо). The distilled liquid does not stay in the hydraulic arrow, but passes through it horizontally, almost without forming a vertical movement.

The water temperature at the supply pipes (T1 and T2) is the same. The same situation is with the branch pipes that are connected to the "return" (T3 and T4). In this mode, the hydraulic valve, by and large, does not affect the operation of the system in any way. However, in this mode, the circuits operate extremely rarely, since the parameters of the system always undergo changes during operation.

Second mode. The principle of operation is as follows: at the moment it happened that the total flow rate on the circuits exceeds the flow rate in the boiler circuit (Qк< Qо). Данная ситуация на практике случается очень часто, когда всем контурам в один момент времени требуется максимальный расход жидкости.

In other words, the immediate need for a coolant is greater than what the boiler circuit can supply. In this case, in the presence of a hydraulic arrow, the system will not get up and not unbalanced. The hydraulic distributor simply creates a vertical ascending flow from the manifold "return" pipe to the supply pipe.

At the same time, hot liquid circulating along the "small" circuit will be mixed with this flow in the upper area of the hydraulic arrow. Temperature balance: T1> T2, T3 = T4.

Third mode. The principle of operation of the hydraulic switch in this mode is, in fact, the main one. In a competently designed and installed heating system, it is he who will be superior. The coolant flow rate in the "small" circuit is greater than a similar total indicator on the collector, that is, the "demand" for the required volume has become lower than the "supply". (Qк> Qo).

There can be any number of reasons for this - from changing the parameters of the thermostatic control equipment to turning off some radiators. None of these factors will adversely affect the overall operation of the heating system.

The excess volume of liquid by a vertical descending flow will simply go to the "return" of the small circuit. In essence, the boiler will provide excess volume, and each of the circuits will take as much as is needed at the moment. Temperature balance for this operating mode: T1 = T2, T3> T4.

How to choose a water gun?

As a rule, a thermohydraulic valve is calculated and selected individually for each heating system. The most important characteristic is the horizontal speed of movement of the coolant inside the HW. Individual manufacturing companies average these parameters and mass-produce a line of hydraulic separators.

Among the manufacturers there are the developers of hydraulic separators who make the calculation and design of the hydraulic system exactly for specific needs. This contributes to the fact that the efficiency of the heating system is increased to maximum values. Basically, hydraulic switches are produced in pairs with a hydraulic manifold.

Appliances can be manufactured in such a way that two or three pipes enter from a heat source. Then the hydraulic arrows are called combined. This model of a hydraulic switch is a convenient alternative to the cascade connection of several boilers and is very convenient - several sources are simultaneously introduced into the hydraulic separator, which saves space in boiler rooms.

D is the diameter of the body of the hydraulic arrow, mm; d - nozzle diameter, mm; P is the maximum power of the boiler, kW; G - maximum flow through the hydraulic separator, m3 / hour; π = 3.14; ω - maximum vertical speed of the coolant through the separator (0.2), m / s; ΔT - temperature difference between supply and return, ° C; C is the heat capacity of water, W / (kg ° C); V is the speed of the coolant through the secondary circuits, m / s; Q is the maximum flow rate in the consumer circuit, m3 / h.

Attention! The approximate size for small devices is selected according to the diameter of the inlet pipes. The distance between the inserts must be at least 10 choke diameters. The height of the body must be substantially greater than its diameter.

Diagrams for self-production of a hydrostatic arrow

When assembling a hydraulic arrow with your own hands, the main thing is to make the calculations correctly and have the skills to work with a welded machine.

First of all, it is necessary to find the optimal dimensions of the hydraulic separator:

inner diameter: divide the sum of all heating boilers' capacities in kW by the temperature difference between the supply and return, extract the square root from the obtained parameter, and then multiply the last value by 49;
height: multiply the inner diameter by six.
spacing between nozzles: multiply the inner diameter by two.

Based on the obtained parameters, you need to draw up a drawing or use one of the schemes of the future hydraulic valve presented by the "Plumber Portal" resource. After that, you need to prepare a steel tube of round or square section, which corresponds to the calculated indicators, and weld the required number of branch pipes with threaded connections into it.

Despite the simplicity of the device, the characteristics of the hydraulic arrow must still correspond to specific conditions. Also, when assembling yourself, you need to understand what to start from.

Attention! All pipe diameters indicated below are not external diameters, but internal diameters, that is, nominal bore!

The classic assembly of a typical hydraulic arrow is based on the “rule of three diameters”. That is, the diameter of the branch pipes is three times less than the diameter of the main cylinder of the separator. The nozzles are diametrically opposite, and their height position is also tied to the main diameter.

Classic low loss header diagram:

Some change in the position of the branch pipes is also used - a kind of "ladder". This modification is focused mainly on more efficient removal of gas and insoluble suspended matter. When circulating through the supply pipe, a slight change in the direction of the liquid flow in a zigzag downward manner contributes to the best elimination of gas bubbles.

On the reverse flow, on the contrary, the step is up, and this simplifies the removal of solid sediment. In addition, this placement promotes optimal mixing of streams. The proportions are chosen in such a way as to create the conditions for the vertical flow velocity in the range from 0.1 to 0.2 meters per second.

Exceeding this limit is prohibited. The lower the vertical flow rate, the more efficient the separation of air and sludge will be. The slower the movement, the better the mixing of flows with different temperatures is. As a result, a temperature gradient is formed along the height of the device.

Diagram of a hydraulic arrow with a stepped arrangement of nozzles:

If the heating system contains circuits with different temperature regimes, then it is worth using a hydraulic valve that performs the functions of a collector, and different pairs of nozzles will have their own temperature pressure. This will significantly reduce the load on the thermostatic devices, make the entire system more manageable, efficient and economical.

The closer the pair of nozzles is to the middle, the lower the temperature head in the supply tube, and the smaller the temperature difference in the supply and return. For example, for batteries, the best mode is 75 degrees in supply with a difference of Δt = 20 ºС, and for a heated floor system, 40 ÷ 45 s Δt = 5 ºС is enough.

Diagram of a low loss header with three outputs to the heating circuits:

Horizontal placement. In such variations, of course, there is no longer any question of removing sediment and air. The location of the fittings differs significantly - for the effective movement of liquid, schemes are often used even in the opposite direction of the "small" and heating circuit flows.

Such a hydraulic arrow is made in order, for example, to more compactly place the equipment in the boiler room, since the opposite direction of flows allows the diameter of the pipes to be slightly reduced. However, in this case, the design must meet certain requirements:

a gap of at least 4d must be maintained between the branch pipes of one circuit;
if the inlet pipes have a diameter less than 50 mm, then the distance between them should not be less than 200 mm.

Variants of horizontal low loss header layouts:

There are also completely "outlandish" designs. For example, one craftsman was able to build a hydraulic arrow from two sections of a conventional cast-iron radiator. This device copes with hydraulic separation without problems. However, this method requires very reliable thermal insulation of the device, otherwise, due to it, absolutely unproductive heat losses will occur.

How to connect a hydraulic switch?

The thermohydraulic valve has its own wiring diagram, which is as simple as its design. The main part of the rules is not so much about the connection as about the calculation of bandwidth and pinout. And yet, understanding the detailed information will make it possible to carry out the installation correctly, as well as to make sure that the selected hydraulic arrow is suitable for installation in a specific heating system.

The most important thing that needs to be clearly understood is that the hydraulic separator will function exclusively in forced circulation heating systems. In this case, the system must have at least two pumps: one in the circuit of the generating part and one more in the consumer. Under other circumstances, the directional valve will act as a zero resistance shunt and therefore short-circuit the entire system.

The hydraulic switch is connected to the direct and return pipes of a boiler or several boilers. Of course, when connecting a device, there should be no hint of a narrowing of the conditional pass. This condition makes it necessary to use pipes with a very significant nominal bore in the piping of the boiler and when connecting the collector, which somewhat complicates the optimization of the arrangement of equipment and increases the amount of materials for piping.

Conclusion: the benefits of using a water arrow

We emphasize once again the advantages of using a hydraulic arrow in a heating system with several circuits:

The functioning of the equipment is smoothed out. The coolant flow through its heat exchanger is always stable, without pressure and temperature surges. The wear resistance of the boiler only increases from this.
A heating system with versatile circuits becomes easily controllable - it is easy to set separate parameters for each circuit, and this will not affect the activity of other elements in any way.
If the boiler is equipped with a cast-iron heat exchanger, then the installation of a hydraulic arrow will protect it from sudden "thermal shocks", which will ultimately increase the service life of expensive equipment.
No problem with pump selection. Each circuit is selected on its own, based on the existing needs. In addition, there is no need to purchase a circulation pump of increased power for installation in the boiler circuit.
Additional capabilities for removing accumulated gases and cleaning the coolant from insoluble contaminants can also become significant.

The need to install a hydraulic arrow in the heating system is considered individually and depends on a number of conditions - the power of the pumps, their interaction, the total power of the system, the presence of additional boilers used in conjunction.

Experts recommend installing this device only when the number of boilers is more than one and the number of pumps is more than three. Otherwise, there is no need for it. It will not damage it, but there will be no benefit from complicating the entire structure.

Thus, a water gun for heating is suitable only for a large branched system, for example, in apartment buildings or large private houses with a large number of outbuildings. Despite the complex principle of operation and a large number of tasks, this mechanism is quite simple in constructive terms, so it is really possible to do it yourself. However, if there are only one or two pumps, this is just a waste of money and a waste of money.