Shotgun for heating

The heating system 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. To achieve such a "harmony" is not so simple, especially if the system is complex, branched, including several contours, differing in both the operating principle and the temperature regime. In addition, heating circuits individual heat exchange devices can have their own devices for automatic adjustment and operation, which by their interference should not affect the functionality of the "neighbors".

Hydrostrel for heating

There are several approaches to achieving such a "unison", but one of the simplest and most effective methods is a very simple, but very effective device - a hydraulic separator, or, as it is often called, a hydro-gun for heating. What is this element, what is the principle of its work, how to correctly calculate and assemble it - in this publication.

What is the hydraulic separator in the

To understand the purpose of the water gun, let's recall how an autonomous heating system works.

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

The simplest single-circuit heating system

The diagram is presented with great simplification. So, it does not show the expansion tank and elements of the security group, simply because of the "simplification" of the figure.

K - boiler, provides heating of the coolant.

N1 - circulation pump, due to the work of which the coolant moves along the supply pipes( red lines) and "reverse"( blue lines).The pump can be installed on a pipe or be part of the boiler design - especially for wall models.

On the closed circuit of pipes the heating radiators( RO) are embedded, providing heat exchange - the heat energy of the coolant is transferred to the premises of the house.

With the right selection of the circulation pump for productivity and the pressure created 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 circuits with natural circulation of the coolant, it is still necessary to install a circulating pump - this will sharply raise the efficiency of the heating system. How to choose circulation pump for heating , how to calculate the optimal parameters of the device - in a special publication of our portal.

• For a small house such a simple scheme can be quite enough. But in the building more often you have to use several heating circuits. We will complicate the scheme.

Is there a single pump with multiple circuits? Not a fact. ..

This figure shows that the pump provides movement of the coolant through the collector( Cl), where it is disassembled into several different circuits. It can be:

- One or more high-temperature circuits with conventional radiators or convectors( PO).

- Water warm floors( VTP), for which the temperature of the coolant should already be much lower, it means that special thermostatic devices will be used. The sensor length of the contours of warm floors also usually exceeds by several times the usual radiator wiring.

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

Will our single pump handle this load with such a coolant flow rate? Probably not. Of course, there are models of high capacity and capacity, with high rates of pressure, but not unlimited possibilities of the boiler itself. Its heat exchanger and internal connections are designed for a certain capacity and pressure, and these values ​​should not be overestimated, as this could well lead to the failure of an expensive boiler plant.

And the pump itself, if it works constantly at the peak of its capabilities, providing the coolant with all the outlines of the branched system, is unlikely to last long. This is not to mention even the increased noise of powerful equipment and a lot of electricity consumption.

• What is the solution - to install on each circuit its own circulation pump, calculated by the parameters of its "subsystem", which it serves.

Operation of several pumps requires mandatory approval, otherwise the system will be unbalanced

So, each circuit has its own pump. Is the problem solved? Alas, this is far from the case - it simply went into a "different plane" and even worsened!

In order for this system to work stably, a very accurate calculation of the pumping equipment is necessary. But even this, most likely, does not make such a complicated scheme of equilibrium. Pumps, as a rule, are connected with the thermostatic regulation systems of each of the circuits, that is, their current, at the moment, performance characteristics - the quantities are changing. One circuit temporarily suspends its work, the other, on the contrary, is turned on. The variants of simultaneous operation or, on the contrary, temporary downtime of all pumps are not excluded. Circulation in one circuit can create inertial, "parasitic" movement of the coolant in another, where it is not currently required - and so on, there can be many different options.

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

And worst of all in this case, the pump installed near the boiler - all the instability of the parameters of the system primarily affects its operation, and ultimately - on the "jerky", not amenable to precise regulation of the boiler. But it is not uncommon in large houses to install two or more boilers cascade - the management of such a system becomes generally extremely difficult, almost impossible task. All this causes a rapid wear of expensive equipment.

• And the output, it turns out, is quite simple - it is necessary to divide the entire hydraulic system not only into the outlets of the final consumption, through the collector, but also to allocate a separate circuit of the boiler.

The balancing problem is solved by installing the

hydraulic separator( hydro-gun) This is exactly the function that the hydraulic arrow( HS) performs. This simple device is installed between the boiler and the collector.

The correct full name of the water gun is a hydraulic separator. The arrow was named, apparently, because it is capable of redirecting the hydraulic flows of the coolant, ensuring the balance of the entire system as a whole.

The construction of a conventional water gun is extremely simple

Structurally this element is a hollow tube of circular or rectangular cross section, damped from both ends, with two pairs of branch pipes - output, for supply, and inlet - for the pipe "return".

As a matter of fact, two interconnected, but, in fact, independent of each other, are formed: a small boiler kennel and a large one, including a collector with all the branches to the other contours. Each of these two circuits has its own flow rate and velocity of the coolant, which do not have any significant influence on each other. Usually the indicator Q1 is a stable value, as the boiler pump runs constantly at one speed, Q2 - changing during 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 reduced hydraulic resistance is created, which allows to equalize the pressure in the small circuit, to put it regardless of the work or idle of the working circuits. In general, this leads to a balanced operation of each of the sections of the heating system, to the smooth functioning of the boiler equipment and the entire system, which is not subject to pressure and temperature jumps.

How the hydraulic separator

works In principle, three modes of hydraulic separator operation are possible.

Illustration	Description of the operation mode of the
	This is an almost ideal, equilibrium state of the system. The pressure created by the small boiler pump is equal to the total head of all heating circuits ( Q1 = Q2) . The inlet and outlet temperature are ( t1 = t3) . A similar situation exists on the "return" sockets ( t2 = t4) . Vertical movement of the coolant is minimal or even completely absent. In practice, if this situation occurs, it is extremely rare, occasionally, since the parameters of the heating circuits have a tendency to change periodically.
	The second situation. The total flow of heating medium in the heating circuits exceeds that of the pump of the ( Q1, ) In ​​fact, it can be characterized that the "demand" for water exceeds what the boiler can "offer." The situation is quite common, In this case, a vertical ascending flow is formed from the return pipe of the large circuit to the delivery branch, moving upwards, the vertical flow is mixed with the hot coolant coming infrom the boiler Temperature mode: t1 & gt; t3, t2 = t4
	The situation is diametrically opposite - the flow rate in the small circuit( not changing nominally) has become higher than the total in the heating circuits ( Q1 & gt; Q2) . Offer "exceeded the" demand "for the coolant Typical reasons for this situation: - the thermostatic equipment is activated on heating circuits or on an indirect heating boiler temporarily shutting down the coolant supply. - temporary complete shutdown of one or more circuits due to lack of demand for heating of certain rooms. - temporary decommissioning of contours for repair or maintenance work. - start of boiler equipment for warm-up, with gradual step connection of working circuits. Nothing critical is happening - the boiler circuit operates in a large part "on itself", pumping the main volume of coolant through a small circle. A vertical downward flow is formed in the hydro-gun itself, from the supply to the "return". Temperature mode: t1 = t3, t2 & gt;t4 . With this mode of operation, the temperature in the "return" quickly reaches the threshold for the automatic shutdown of the boiler equipment, which ensures rational use of fuel.

The hydraulic separator can perform a number of useful functions.

• First of all - the promised remark about the heating system is not the most branched type. Shooting can be useful, and sometimes even - and an obligatory element in the event that the heat exchanger of the boiler 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 brittleness. A sharp temperature drop with a large amplitude can lead to a crack in the cast iron part. Thus, when the heating system is ignited in the cold season, a very significant temperature difference can arise - in the furnace and in the pipe, return flows. Heating the coolant in a large circuit will take a long time, and this period is very critical for a cast-iron heat exchanger. But if the contour is "shortened", that is, run through a hydraulic separator, heating of the coolant will be much faster, and the probability of deformation of the boiler's heat exchanger will be minimal.

By the way, some manufacturers of boiler equipment with cast-iron heat exchangers directly point to the need for installation of a hydro-gun - violation of these requirements entails termination of warranty obligations.

• The sudden expansion of the volume in the pipe of the shunting and the resulting drop in the velocity of the fluid can be additionally "put into service".

Possible additional functions of the water gun - air separation and cleaning of the coolant from solid suspensions

1. Completely eliminate the formation of gas in the coolant - almost impossible, therefore in the heating system installed drain valves Maevsky or automatic air vent - in the safety group, radiators, etc. Very efficient, due to the large volume, the separator of air is able to become a hydraulic separator. To do this, an automatic air vent is placed on top of it( key 1).In addition, on the models of factory production, often a special fine mesh net is installed inside the cylinder, which facilitates the active separation of dissolved air from the liquid and its subsequent discharge through a separator.
2. A sharp slowing of the flow velocity promotes the gravitational settling of solid suspensions, the appearance of which is quite likely in the coolant. If a faucet is installed from below( item 2), it will be possible to regularly clean the system of accumulated sludge.

Video: Animated demonstration of hydraulic separator function

Specificity of hydraulic separator

design As can be seen from the above, the design of the hydraulic separator is quite straightforward. Nevertheless, it must obey certain rules.

For sale in specialized stores, you can find many offers, different sizes and configurations, that is, it is possible to choose a model that is the most suitable for the parameters under the existing or planned heating system. Quite often there are original models that constructively combine both the hydraulic separator and the manifold for connecting the circuits. Sometimes you can see the gunshots and generally an unusual stellar configuration.

Various options for hydraulic dividers factory-made

However, if you look at the cost of these products, then certainly there will be the idea of ​​the possibility of independent production. Indeed, for the owner of the house, familiar with metalwork and welding work to mount a hydraulic separator - should not be difficult. The main thing is to observe the recommended size parameters, which will ensure the optimal functionality of the device.

The classic layout of the hydraulic separator is based on the rule of "three diameters".How it looks is shown in the diagram.

"Classic" scheme on the principle of "three diameters"

Diameters, of course, show an internal, conditional pass, regardless of the thickness of the walls.

Another similar scheme - with nozzles, alternating in height. Its proportions are shown in the second scheme.

Scheme with alternating spigots for height

It is believed that the "step down" for the feed will promote better separation of gases, and "step up" on the return is more effectively separated by solid suspensions.

How to calculate the diameter of the D-Shooter - will be described in the next section of the publication. In the meantime, it's worth noting that this ratio of diameters is not chosen randomly. One of the main goals is to ensure the speed of vertical streams in the range of 0,1 ÷ 0,2 m / s, not more. What it is for:

• The minimum speed ensures maximum cleaning of the coolant from the slurry, contributes to better air separation.
• At a low speed, the highest quality natural convection of hot, from the supply, and cooled, from the "return" of the coolant is ensured. This creates a certain temperature gradation in height - a similar property is often used using a water gun 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 the thermoregulating equipment, to increase the overall efficiency of each of the circuits and the entire system as a whole.

Hydraulic separator, allowing to achieve a temperature gradient in height

It should be said that the vertical location of the gun, although considered "classical", is by no means a dogma. If you do not take into account the functions of separation from the air coolant and the collection of solid suspensions, then, depending on the specific conditions of the pipes in the heating system, you can take a horizontal option. Moreover, even the location of the feed and return ducts of the boiler and heating circuits can also vary. A few examples are presented in the diagram below.

Possible horizontal layout of hydraulic separator

With this arrangement of the hydraulic separator, the requirement to minimize the flow rate in it goes to the "second plan" - separation of precipitation is not 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 a smaller diameter pipe when manufacturing. But at the same time, it is necessary to create conditions to ensure qualitative mixing. To this end, the supply and return connections of each of their circuits must be spaced apart by at least four diameters d, and at the same time with any diameter of the branch pipe this distance can not be less than 200 mm.

Example of a mounted

Horizontal Shooter The firearm is not necessarily always a welded steel structure. You can meet a lot of examples, when the masters of them are made of copper pipes or even polypropylene - such a device will generally cost quite inexpensively. However, when using plastic, the temperature regime in the separation system should not exceed a maximum of 70 ° C.

Hydraulic separator is made of polypropylene pipes

You can also find absolutely unexpected solutions. For example, a hydraulic separator is made of pipes of small diameter, giving it the appearance of a lattice. With this approach, it is possible to confine ourselves to polypropylene or even metal-plastic pipes Ø 32 mm.

Lattice hydraulic separator of small diameter pipes

Following the same principle, some masters install instead of such a grate several sections of the old waste radiator. With the function of the hydraulic separator, such a device will cope fully. True, it is necessary to take into account the fact that large heat losses are inevitable. We will have to think over the quality thermal insulation of such an improvised water gun.

Calculation of the standard hydraulic separator

The commercially available hydraulic separators are designed for a certain power of the heating system. But if it is decided to produce this, in principle, a simple design, it is important to calculate the basic parameters - the minimum diameter of the shunting gun itself and the diameters of the supply pipes. After that, guided by the diagrams presented above, it will be easy to compose your own drawing.

Below you will find two options for calculating the hydraulic separator of the "classic" vertical type.

Calculation of the heating system power

There is a universal formula describing the dependence of the coolant flow rate on the total heat demand, the heat capacity of the coolant and the temperature difference in the supply pipes and the "return"

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 × ° C or 1.164 W × h / kg × ° C or 1.16 kW / m³ × ° C)

Δt - difference of temperatures on the feed and "return", ° С.

However, the flow rate for fluid flow through the pipe is:

Q = S × V

S - cross-sectional area of ​​the pipe, m²;

V - flow velocity, m / s.

S = Q / V = ​​W /( with × Δt × V)

It has been proven by experience that for optimal mixing in a hydraulic separator, for a quality separation of air and precipitation of sludge, the speed in it should not be higher than 0.1 -0.2 m / s. Once the unit of measure is chosen, then multiply by 3600 seconds. It turns out to be 360 ​​- 720 m / hour. If the calculation is for water, several initial values ​​can be entered immediately to simplify the

formula S = W /( 1.16 × Δt × 540) = W /( 626 × Δt)

Having determined the cross-section, it is not difficult to determine the required diameter by the formula of the area of ​​a circle.

D = √( 4 × S / π) = 2 × √( S / π)

Substituting the values:

D = 2 × √( W /( 626 × Δt × π)) = 2 × √( W /( 1966(W / Δt)

= 0.0451 × √( W / Δt)

Since the value will be received in meters, which is not very convenient, you can translate it directly into millimeters,multiplying by 1000.

As a result, the formula will take the following form:

• D = 45,1 √( W / Δ t ) - for the flow rate in the pipe of the water gun at 0.15 m / s.

It is easy to calculate both the values ​​for the upper and lower limit of the permissible flow rate:

• D = 55,2 √( W / Δ t ) - for speed in 0,1 m / s;
• D = 39.1 √( W / Δ t ) The is for a speed of 0.2 m / s.

Having determined the diameter of the hydro-gun, it is easy to calculate the diameters of the inlet and outlet nozzles.

The built-in calculator, located below, will help you to calculate quickly:

Calculator for calculating the recommended parameters for the power-generating and temperature difference

return temperature Calculation of the parameters of the water gun based on the performance of the

pumps There is another way to determine the required minimum dimensions of the hydraulic separator. In this case, the initial values ​​will be taken from the output of the pumps in the boiler circuit and all heating circuits and, if available, hot water supply.

As it was already clear from the description of the principle of operation of the water gun, its main purpose is not to overload the pumping equipment of the boiler plant, while ensuring the proper flow of the coolant in all heating circuits. So in practice, it turns out that the total capacity of all pumping units is always higher than the same pump that circulates directly through the boiler.

In the most "peak" version, when all pumps are simultaneously used in all circuits, the total throughput through the water gun is equal to the difference:

Q = ΣQot. - Qcot.

ΣQuote. - total capacity of all pumps on heating circuits and, if any, on an indirect heating boiler, m³ / h

Qcot. - capacity of the circulation pump in the small circuit of the heating boiler.m³ / hour.

Let's return again to the formulas that were discussed above.

S = W /( s × Δt × V)

The power, as already shown above, is:

W = Q × s × Δt

Therefore,

S =( Q × s × Δt) /( s × Δt ×V) = Q / V

From here, there is very little to determine the diameter:

D = √( 4 × S / π) = 2 × √( Q /( π × V)) = 2 × √( (ΣQot..) /( π × V))

It is not difficult to specify the passport characteristics of the installed or planned pumping equipment. The only thing, in the calculations do not forget to bring the value of productivity to the same values ​​- m³ / hour, and the flow rate through the hydro-gun - to m / hour. The result will remain reduced to millimeters, multiplying by 1000.

You can immediately simplify the formula by entering the constants and the recommended flow rate, as in the first calculation. As a result, the following expressions are obtained:

At a vertical flow rate equal to:

• 0.1 m / s: D = 59.5 × √( ΣQot - Qkot.)
• 0.15 m / s: D = 48,6 × √( ΣQot.-Qc.)
• 0,2 m / s: D = 42,1 × √( ΣQot - Qcot.)

These ratios are included in the calculator below:

Calculator for calculating the parameters of the gunfrom the performance of the

The calculated values ​​are the minimum. If the diameter is higher, then no harm from this will happen - the smooth operation of the heating system will only benefit. But zauzhenie below the calculated value - is unacceptable!

Naturally, with the purchase or self-manufacturing of the hydraulic separator are guided by the standard pipe diameters, but only those resulting from the results necessarily in the larger side.

Conclusion

Summing up the publication, will once again highlight the main advantages of a heating system equipped with a hydraulic separator:

• The cast-iron heat exchanger of the boiler receives a reliable protection against thermal shock. Which extends the life of the boiler equipment.
• Pump selection is much simplified. For each circuit, it is fashionable to purchase a device of the required capacity, and this does not require the installation of a powerful pump in the boiler circuit - the hydro-gun will completely eliminate this imbalance.
• The flow rate of the heating medium through the boiler is stable, that is, the equipment always operates in its regular optimum mode, without pressure and temperature jumps.
• The entire heating system is balanced, all circuits are independent and do not have a significant effect one on another.
• It is possible to remove sludge and gases.

And finally - another video story about the importance of the firearms in the heating system:

Video: How important is the hydro-gun in the branched heating system?