Schemes of heating systems with two or more boilers. Two boilers in a boiler room - how to connect - pros and cons How to combine two heating boilers into one

A home heating system based on two boilers is a fairly common solution that allows you to save a lot of money. Usually one of the boilers - the main one - is a gas boiler, easy to operate, but running on expensive fuel. The second is a solid fuel boiler, less convenient, requires constant monitoring and periodic fuel supply, but more economical ( solid fuel- coal, wood - much cheaper than gas). When using two boilers, it is rational to combine them into one system and, if necessary, turn on or off the additional boiler. But the operation of these heaters has a number of differences that must be taken into account when planning their connection scheme.

Adjustment of excess pressure in the heating system

The operation of a solid fuel boiler is associated with such a phenomenon as a significant increase in pressure in the system due to an increase in temperature, which is quite difficult to control. To protect the system in such cases, an open expansion tank is used, connected to the atmosphere, which allows the coolant (water) to expand without increasing the pressure in the pipes. At a temperature exceeding the norm, the excess of heated water simply flows through the hole in the tank into the sewer.

An open expansion tank is the main difference between a solid fuel boiler and a gas boiler. The latter is equipped with automation that controls the temperature and pressure in the system, preventing the coolant from overheating. The advantage of such a closed self-regulating system is that a minimum of oxygen from outside enters it, reducing the risk of corrosion. metal parts. But such a system also has a certain excess pressure, which is regulated by a safety valve and an expansion tank, only they are mounted in the boiler body itself, and not separately, like in solid fuel boilers.

How to make heating with two boilers

So, there are two boilers that differ side by side design features. How can you combine them in one system? The most effective is the option of dividing the system into two independent circuits using a heat exchanger. One of the circuits is open, equipped with a solid fuel boiler; the second - a gas boiler and radiators. Both circuits are loaded on one heat exchanger.

When planning such a system, it is necessary to take into account the position of all the main and connecting elements, so that during operation, maintenance or repair they can be easily found, inspected, and replaced if necessary. Therefore, before starting the installation, it is better to draw a diagram, put equipment on it, outline the laying of pipes, and mark the places for installing additional elements.

Requirements for premises with a solid fuel boiler

For the premises in which boilers are installed, a number of requirements are put forward by regulatory documents, depending on the type of boilers. Solid fuel boilers with a power of 30 kW or more can only be installed in rooms specially equipped for them. The boiler room should be centrally located relative to the rooms that are heated, on the same level with them or in the basement, which will allow the generated heat to be used with maximum efficiency, and a minimum of energy will be spent on maintaining circulation. Fuel cannot be stored directly in the boiler room, it is usually stored in an adjacent room. An exception is when boilers of small power up to 30 kW are used, then the fuel supply can also be kept in the boiler room itself in boxes at a distance of at least 1 m from the boiler. Since solid fuel, unlike gas, has to be harvested independently, it is advisable to do this once for the entire heating season, and for this it is necessary to have a sufficient area for its storage, which must be taken into account when choosing a room.

The boiler must not be installed on the floor, but on a foundation or foundation made of non-combustible materials. The surface of the base or foundation must be strictly horizontal and extend beyond the boiler by 0.1 m on the sides and rear and by 0.3 m in front. For boilers with a power of up to 30 kW, the floor can be made of combustible materials, such as wood, but then a steel sheet 0.7 mm thick must be attached around them, which extends beyond the boilers by 0.6 m on all sides. Under the boilers, the floor, foundation or base must be non-combustible.

The walls, partitions and ceilings of the boiler room must have a fire resistance of at least 0.75 hours. When the boiler room is located above the living quarters, its floor, the places where pipes pass through the holes in the floor, door sills, as well as walls at a height of 10 cm must be protected waterproofing material. A prerequisite when choosing a room for a boiler room, it is necessary to have sufficient natural lighting (at least 0.03 m2 per 1 m3). The height of the boiler room should not be less than 2.5 m. The area of the boiler room should provide access to all elements of the system for the purpose of their inspection or repair. Minimum distances between the boiler and walls (partitions) should be 1 m from the front side and 0.6 m from all the others. The minimum volume of the boiler room depends on the power of the boiler used: for a boiler with a power of up to 30 kW - 7.5 m3, a power of 30 to 60 kW - 13.5 m3, a power of 60 to 200 kW - 15 m3.

Ventilation of the boiler room

For normal operation boiler room, the boiler room must have a ventilation system, not only exhaust, but also supply. An opening with an area of 200 mm2 or more is used as an inlet channel, and a ventilation channel with a section of 14x14 cm is used as an exhaust duct, the entrance of which is located under the ceiling (for boilers with a power of up to 30 kW). The area of the inlet of the hood should be the same as the section of the ventilation duct. The hole itself is usually closed with a grate. Both the supply and exhaust ducts should not have any dampers - they should always be open and preferably clean. When using more powerful boilers (from 30 kW and above) ventilation holes must have a cross section of at least 20x20 cm and not less than half the cross section of the chimney.

The opening of the supply channel is best made behind the boiler, its height above the floor level should not be less than 1 m. An air duct of the same cross section can also be used as a supply channel. When using an air duct, it is allowed to have a damper that regulates air flow, but it should not overlap the channel by more than 80%.

All ventilation ducts are made of non-combustible materials. You can not install a forced system exhaust ventilation if the chimney is with natural draft.

Sewerage

To drain excess water when it overheats, the boiler room must be equipped with a sewerage system connected to the sewerage of the house by a floor drain. If for some reason this cannot be done, a well is equipped in the boiler room with hand pump. When overheated, water will accumulate in it, and pumped out with the help of a pump. To supply water to the boiler, the system is equipped with an intake valve, in front of which a check valve is also usually mounted. The boiler is connected to the cold water system with a flexible hose.

Requirements for rooms with gas boilers

Now consider the requirements that are put forward for rooms with gas boilers. Gas boilers, the power of which does not exceed 30 kW, can be installed on any of the floors in almost all rooms, except for those in which people are constantly present (bedrooms, living rooms, children's rooms, as well as garages and landings if the boilers are equipped open cam combustion). When using liquefied gases, there are more restrictions, for example, they cannot be installed in basements or basements. Boilers with a power exceeding 30 kW are installed in separate rooms with a ceiling height of at least 2.5 m. The volume of the room for gas boilers with a power of up to 30 kW must be at least 7.5 m and a gas stove for 4 burners, the minimum volume of such a kitchen is 15 m3.

Ventilation of a room with a gas boiler

To ensure air supply to the room with a gas boiler, an inlet with a cross section of at least 200 cm2 is used, located at a height of no more than 30 cm from the floor. Air can come from outside or from adjacent rooms.

In boiler rooms where liquefied gas boilers are installed, the exhaust opening must be at the bottom at floor level, and the exhaust duct must slope outwards. This is due to the fact that liquefied gas heavier than air, and if it leaks, it will sink down. The air inlet should also be at floor level and have a cross section of 200 cm2.

Structural materials and heating systems

The floor under the gas boiler must be made of non-combustible materials or covered with steel sheet or other non-combustible material, extending 0.5 m beyond the boiler. The same applies to walls if the boiler is attached to them.

Gas pipelines are made of steel seamless pipes or straight-seam electric-welded pipes. It is also possible to use copper pipes with a wall thickness of at least 1 mm indoors.

In a heating system for heat carriers, copper or plastic pipes. When using plastic pipes in places where the temperature is high enough, for example, near the boiler, their sections should be replaced with pipes made of copper or steel. Copper pipes are sensitive to mechanical damage, therefore, when using them, it is necessary to install filters that do not allow small particles to enter the system. Inside copper pipes, their walls are covered with a protective layer of copper oxide, and solid particles can damage it.

When installing copper pipes, their edges must be carefully sanded so that there are no sharp edges, and wrapped inward. Rough edges can cause system flow turbulence, noise, bacteria build-up and damage to the pipe lining. Copper pipes must be correctly selected in diameter - too thin pipes with high water pressure can quickly fail due to a protective layer damaged by strong pressure. In addition, thin pipes increase the load on the pump and impair the operation of the boiler burner. And one more nuance concerning copper pipes. When using pipes with a diameter of less than 28 mm, it is undesirable to connect them by soldering, since high temperature affects their structure, significantly reducing strength and resistance to oxygen.

Installation of two boilers in pairs. Video

The creation of a heating circuit in which two boilers in a heating system work either alone or together is associated with the desire to provide redundancy or reduce heating costs. The joint operation of boilers in an integrated system has a number of connection features that should be considered.

Possible options - two boilers in one heating system:

gas and electricity;
solid fuel and electricity;
solid fuel and gas.

Combining a gas boiler with an electric boiler in one circuit, as a result of which a heating system with two boilers is created, can be implemented quite simply. Both serial and parallel connection is possible. In this case, a parallel connection is preferable, because. you can leave one boiler running and the other completely shut down, switched off or replaced. Such a system can be completely closed, and ethylene glycol can be used as a coolant for heating systems or.

Joint operation of a gas and solid fuel boiler

This is the most difficult option for technical implementation. In a solid fuel boiler, it is extremely difficult to control the heating of the coolant. Typically, these boilers operate in open systems, and the excess pressure in the circuit during superheating is compensated in the expansion tank. Therefore, it is impossible to directly connect a solid fuel boiler to a closed circuit.

For the joint operation of a gas and solid fuel boiler, a multi-circuit heating system has been developed, which consists of two independent circuits.

The gas boiler circuit operates on radiators and on a common heat exchanger with a solid fuel boiler and with an open expansion tank. For a room in which both boilers are installed, it is necessary to fulfill the requirements for both gas and solid fuel boilers

Joint operation of solid fuel and electric boilers

For such a heating system, the principle of operation depends on the type. If it is intended for open heating systems, then it can easily be connected to an existing open circuit. If the electric boiler is intended only for closed systems, then the best option will be - joint work on a common heat exchanger.

Dual fuel heating boilers

To increase the reliability of heating and to avoid interruptions in the operation of the heating system, dual-fuel heating boilers operating on different types fuel. Combination boilers are made only in the floor version due to the rather large weight of the unit. The universal unit can have one or two combustion chambers and one heat exchanger (boiler).

The most popular scheme is the use of gas and firewood to heat the coolant. It should be taken into account that solid fuel boilers can only work in open heating systems. To realize the benefits closed system an additional circuit for the heating system is sometimes installed in the universal boiler tank.

There are several types of dual-fuel combined boilers:

gas + liquid fuel;
gas + solid fuel;
solid fuel + electricity.

Solid fuel boiler and electricity

One of the popular combined boilers is a solid fuel boiler with an electric heater installed. This unit allows you to stabilize the temperature in the room. Thanks to the use of heating elements, such a combined boiler has acquired a lot of positive qualities. Consider how the heating system works in such a combination.

When igniting fuel in the boiler and when connecting the boiler to electrical network heating elements that heat the water immediately begin to work. As soon as solid fuel flares up, the coolant quickly heats up and reaches the temperature of the thermostat, which turns off the electric heaters.

The combi boiler runs on solid fuel only. After the fuel burns out, the water begins to cool in the heating circuit. As soon as its temperature reaches the thermostat threshold, it will turn on the heating elements again to heat the water. Such a cyclical process will maintain a uniform temperature in the rooms.

To optimize the heating circuits, heat accumulators in heating systems were invented, which are a large volume tank from 1.5 to 2.0 m3. During the operation of the boiler, a large volume of water is heated from the pipes of the circuit passing through the accumulator tank, and after the boiler stops working, the heated water slowly gives off thermal energy into the heating system.

Heat accumulators allow you to maintain a comfortable temperature for quite a long time.

In order to avoid critical situations in winter, reduce heating costs and ensure its reliability, many owners prefer either installing a system with two boilers using different fuels, or installing. These heating options have certain advantages and disadvantages, but they fully provide their main task - stable and comfortable heating.

We assemble the boiler room from A to Z...

Any boiler room is the heart of the system and. In this article I will tell you how to assemble a boiler room so that it at least has a well-functioning heating and water supply system. Using these algorithms, you can maximize the effect of the system.

Video:

I will teach you how to calculate and assemble such a heating system.

In this article you will learn:

Anyone who plans to supply natural gas to a boiler room should familiarize himself with the requirements for boiler rooms with gas boilers.

Any heating project where a house is planned to be heated begins with a calculation of the heat loss of a given house. About how to calculate houses, SNiPs, GOSTs and various literature have been developed for calculating heat losses. One of the SNiPs is SNiP II-3-79 "Construction Heat Engineering".

I want to talk a little about thermal calculations. In fact, the calculation of heat is not carried out by some devices, as some might assume. Any engineers at the design stage use pure or theoretical science, which allows, using only known materials from which the house is made, to calculate the heat lost. Many engineers use special programs to speed up, one of which I personally use.

The program is called: "Valtec Complex"

This program is absolutely free and can be downloaded from the Internet. To find this program, simply use the search in Yandex and enter the search line: "Valtec Complex Program". If you do not find this program on the Internet, then contact me and I will tell you the direct address. Just write in the comments on this page and I will answer there.

Solution.

For the solution, a universal formula is used:

W - energy, (W)

C - heat capacity of water, C \u003d 1163 W / (m 3 ° C)

Q - consumption, (m 3)

t1 - Cold water temperature

t2 - Hot water temperature

Just paste in our values, don't forget to take the units into account.

Answer: For each person, 322 W / h is needed.

Such a filter filters large crumbs in order to eliminate blockage in the boiler. The boiler with such a filter will last much longer than without it.

Also installed on the return line. But often they put it on the supply line.

The first reason why we put a check valve on the return line of the heating system.

The non-return valve serves to prevent the reverse movement of the coolant in cases where two boilers are installed in parallel. But this does not mean that it does not need to be put on the return line when one boiler is installed.

For the second reason a non-return valve is placed on the supply line, in order to exclude the reverse movement of the coolant in order to prevent debris from entering the heating system through the supply line.

How to connect two boilers

Maximum level of connection of two boilers with valves

Advantages of working two boilers in pairs

If one boiler fails, the heating system will continue to work.

You do not need to buy one powerful boiler, you can buy two weak boilers.

Two weak boilers working together give out much more heated coolant, since some powerful boilers have a small passage diameter. Due to the small passage diameter, the coolant flow through the boiler, to put it mildly, remains insufficient for big house. Although there are schemes that allow you to increase consumption. We'll talk about this below.

Disadvantages of two working boilers in pairs

The cost of two weak boilers is much higher than one powerful boiler.

Two pumps will not be justified. Although two pumps can work quite well in economy mode than one tuned for high speeds.

Regarding the selection of pipe diameter

As far as I know, there are three ways to determine:

Philistine way- this is the selection of the diameter by determining the speed of movement of water in the pipeline. That is, the diameter is selected so that the speed of water movement does not exceed 1 meter per second for heating. And for water supply it is possible and more. In short, they saw and copied somewhere, repeated the diameter. Also find all sorts of recommendations from experts. Some are taken into account average. In short, the philistine method is the most non-economic one, and the most malicious mistakes and violations are made in it.

Practice-acquired- this is a method in which schemes are already known and special tables have been developed in which all diameters are already available and additional parameters are indicated for the flow rate and speed of water movement. This method is usually suitable for dummies who do not understand calculations.

The scientific way is the most perfect calculation

This method is universal and makes it possible to determine the diameter for any task.

I watched a lot of tutorial videos, and tried to find calculations for determining the diameters of the pipeline. But I couldn't find a good explanation on the internet. Therefore, for more than 1 year on the Internet there has been my article on determining the diameter of the pipeline:

And someone generally uses special programs, according to the calculations of hydraulics. Moreover, I even found incorrect and unskilled hydraulic calculations. Which are still walking on the Internet and many continue to use an unreasonable method. In particular, the hydraulics of heating systems are not correctly considered.

To accurately determine the diameter, you need to understand the following:

And now attention!

The pump pushes the liquid through the pipe, and the pipe with all the turns gives resistance to movement.

The force of the pump and the force of resistance is measured by only one unit of measurement - these are meters. (meters of water column).

In order to push the liquid through the pipe, the pump must cope with the resistance force.

I developed an article that describes in detail:

Any pump has two parameters: head and flow. Therefore, all pumps have pressure-flow graphs, which show how the flow changes depending on the resistance of the liquid in the pipe.

To select a pump, it is necessary to know the resistance created in the pipe at a certain flow rate. You must first know how much liquid will need to be pumped per unit of time (flow rate). At the specified flow rate, find the resistance in the pipeline. Further, the pressure-flow characteristic of the pump will show whether such a pump is suitable for you or not.

In order to find resistance in the pipeline, the following articles have been developed:

At the design stage, you can find the consumption of the entire system, it is enough to know the heat loss of a particular building. This article describes the algorithm for calculating the coolant flow rate for certain heat losses:

Consider a simple problem

There is one boiler and a two-pipe dead end. See image.

Pay attention to the tees, they are indicated by numbers ... When explaining, I will indicate this: Tee1, tee2, tee3, etc. Also note that the costs and resistances in each branch are indicated.

Given:

Find:

Diameters of pipelines of each branch
Select the pressure and flow of the pump.

Solution.

Find the total flow of the heating system.

We assume that the temperature of the supply line is 60 degrees, and the return line is 50 degrees.

then, according to the formula

1.163 - heat capacity of water, W / (liter ° C)

W - power, W.

where T 3 \u003d T 1 -T 2 is the temperature difference between the supply and return pipelines.

The temperature difference is set from 5 to 20 degrees. The smaller the difference, the greater the flow rate and, accordingly, the diameter increases for this. If the temperature difference is greater, then the flow rate decreases and the pipe diameter may be smaller. That is, if you set the temperature difference to 20 degrees, then the flow rate will be less.

Find the diameter of the pipeline.

For clarity, it is necessary to bring the diagram into a block form.

Since the resistance in the tees is very small, it should not be taken into account when calculating the resistance in the system. Since the resistance of the length of the pipe will many times exceed the resistance in the tees. Well, if you are a pedant and want to calculate the resistance in a tee, then I recommend that in cases where the flow is more for a 90-degree turn, then use the angle. If less, then you can close your eyes to it. If the movement of the coolant is in a straight line, then the resistance is very small.

Resistance1 = branch 1 from tee2 to tee7
Resistance2 = radiator branch2 from tee3 to tee8
Resistance3 = radiator branch3 from tee3 to tee8
Resistance4 = branch 4 from tee4 to tee9
Resistance5 = radiator branch5 from tee5 to tee10
Resistance6 = radiator branch6 from tee5 to tee10
Resistance7 = path from tee1 to tee2
Resistance8 = path of pipe from tee6 to tee7
Resistance9 = path of pipe from tee1 to tee4
Resistance10 = path from tee6 to tee9
Resistance11 = pipe path from tee2 to tee3
Resistance12= pipe path from tee8 to tee7
Resistance13 = path from tee4 to tee5
Resistance14= pipe path from tee10 to tee9
Main branch resistance = from tee1 to tee6 along the boiler line

For each resistance, you need to choose a diameter. Each section of resistance has its own flow. For each resistance, it is necessary to set the declared flow rate depending on the heat loss.

Find the costs for each resistance.

To find the flow in resistance1, you need to find the flow in radiator1.

The calculation of the diameter selection is carried out cyclically:

Further calculations for this problem are laid out in another article:

Answer: The optimal minimum flow rate is: 20l/m. At a flow rate of 20 l / m, the resistance of the heating system is: 1m.

Of course, it is also necessary to take into account the resistance of the boiler, which can be taken as approximately 0.5 m. Depending on the diameter of the passage of the boiler itself. In general, to be more precise, it is necessary to calculate through the tubes in the boiler itself. How to do this is described here:

How to tie a water heating system for a very large house

There is a universal scheme for water heating systems, which allows you to make the system more perfect, functional and very productive.

Above, I already explained why these elements are needed:

Hydrogun- it's actually a hydraulic separator, detailed explanation and the calculation of hydraulic guns is explained here:

But I will repeat myself a little and explain some more details. Consider a diagram with a hydraulic separator and a manifold together.

V1 and V2 should not exceed the speed of 1 m / s with an increase in speed, unjustified resistance occurs at the inlet and outlet of the nozzles.

V3 should not exceed the speed of 0.5m/s, as the speed increases, resistance from one circuit to another comes into play.

F - The distance between the nozzles is not regulated and is taken as the minimum possible in order to comfortably connect various elements (100-500mm)

R- The vertical distance is also not regulated and is taken as a minimum of 100mm. Maximum up to 3 meters. But the distance (R) of the diameters of the four nozzles (D2) will be more correct.

The main purpose of the hydraulic arrow is to obtain an independent flow rate that will not affect the boiler flow rate.

The main purpose of the collector is to divide one stream into many streams so that the streams do not affect each other. That is, so that a change in one of the collector streams does not affect other streams. That is, a very slow movement of the coolant occurs in the collector. slow speed in the collector has less effect on the flows leaving it.

We disassemble the inlet diameter from the boiler D1

One of the calculations of the diameter is the following formula:

It is necessary to strive for the minimum speed of movement of the coolant. The faster the coolant moves, the higher the resistance to movement. The greater the resistance, the slower the coolant moves and the weaker the system heats up.

A task.

And let's try to increase the diameter to 32mm.

Then the schedule will look like this.

Maximum consumption 29 l/m. The difference from the original to 4l / m.

It's up to you to decide whether the game is worth the candle ... Further increase will lead to a waste of money on a large diameter.

Further, I take into account that there will be a flow rate of 29 l / m from each boiler. the consumption from two boilers will be equal to 58 l / m. Now I want to calculate what diameter to choose for the pipe connecting two boilers and entering the hydraulic arrow.

Finding the diameter after the tee

Given:

At a flow rate of 58 l / m, the resistance was: 0.85 m, basically the resistance creates about 0.7 m. To reduce the resistance of the sump filter, it is enough to increase its diameter or thread on it. The greater the permeability of the sump filter, the less resistance in it.

Therefore, we make a decision: Do not increase the diameter, but increase the sump filter, with a thread of up to 1.5 inches.

With this effect, we will significantly increase the total heat flow from the boiler to the hydraulic gun.

Also, by this effect of increasing the flow through the boiler, we increase the efficiency of boilers.

Also, if we want to reduce the resistance of the check valve, then the thread on it should be increased. Therefore, we accept with a thread of 1.25 inches.

Ball valves should be selected in such a way that the internal passage does not narrow or increase, but exactly repeats the passage itself. Choose a passage in the direction of increasing diameter.

More about hydroguns:

According to the task:

Consumption of warm floors: 3439 l/h at a temperature difference of 10 degrees.

400m 2 x 100W / m 2 \u003d 40000 W

As for radiator heating, the principle of operation of various schemes. I have not yet prepared articles on this topic, since most people know how to do this, at least approximately. But there are plans to touch on this topic, and to prescribe strict laws and calculations for the development of schemes in space.

As for warm water floors

The diagram shows that warm water floors are connected through. The circuit through the three-way valve forms.

mixing unit is a special piping chain that forms the mixing of two different streams. In this case, for there is a mixing of two streams: the heated coolant from the collector and the cooled coolant returned from the warm floors. Such a mixture, firstly, gives a lower temperature, and secondly, it adds consumption to warm floors. Additional flow accelerates the flow of coolant through the pipes.

Engineering calculation of diameters for the required flow

For these calculations, I developed a section:

How to get rid of air in the heating system in a constant mode?

The most ideal way to get rid of air in automatic mode serves as an element: Automatic air vent. But for its effective use, it must be installed on the highest supply pipeline of heating systems. In addition, you need to create an area of \u200b\u200bspace in which air will be separated.

See diagram:

That is, the outgoing coolant from the boiler must first of all rush upward to the air separation system. The air separation system consists of a tank with a thickness larger diameter 6-10 times the branch pipe included in it. The air separator tank itself must be at the highest point. The top of the tank should be .

The inlet pipe should be at the top, and the outlet from it at the bottom.

When the coolant has a low pressure, then the gases in it begin to be released. Also, the hottest coolant has a more intense outgassing.

That is, by driving the coolant to the very top, we reduce its pressure and thereby the air begins to be released more intensively. Since the coolant immediately going to the air separator tank has the highest temperature and, accordingly, gas evolution will be intense.

Therefore, for ideal air release in the heating system, two conditions must be met: These are high temperature and low pressure. The lowest pressure is at the highest point.

For example, you can try to install a pump after the air separator tank, thereby reducing the pressure in the tank.

And why is this method of air release not used everywhere?

This method of air release has long been known!!! In addition, it removes the hassle of air release by an order of magnitude.

How to connect a solid fuel boiler

As you know, solid fuel boilers are at risk of overheating due to the failure of air shut-off mechanisms. For the safe use of solid fuel boilers for heating systems from high temperatures, two main elements are used.

How a capacitive low loss header works is described here:

Why are high temperatures dangerous for heating systems?

If you have plastic pipes such as polypropylene, metal-plastic and, then direct connections of such pipes to a solid fuel boiler are contraindicated.

The solid fuel boiler is connected only with steel and copper pipes capable of withstanding temperatures over 100 degrees.

Pipes that can withstand high temperatures are assembled with a temperature limit.

Three-way valves are mainly used with large bores and servomotors. with mechanical movement of valves have a very narrow bore, so check the flow charts of these three-way valves.

A three-way valve in the boiler circuit serves to prevent low temperature With . Such a three-way must let the coolant into the boiler at least 50 degrees.

That is, if the heating system is below 30 degrees, then it begins to open the boiler circuit inside the boiler itself. That is, the outgoing coolant from the boiler immediately enters the boiler on the return line. If the boiler temperature is above 50 degrees, it starts to start the cold coolant from (from the tank). This is necessary in order not to cause a strong overload in temperature in the boiler circuit, since a large temperature difference causes condensate on the walls of the heat exchanger, and also reduces the favorable annealing of firewood. In this mode, the boiler will last longer. Also, the ignition of the boiler will be faster and more efficient than if the boiler was constantly supplied with ice coolant.

The temperature of the solid fuel boiler must be at least 50 degrees. Otherwise, it is necessary to reduce the temperature of the three-way valve not to 50, but below degrees to 30.

With a low temperature heating of 50 degrees, a decrease in the temperature of the three-way valves must be taken into account. If you set 50 degrees on the boiler, then set 20-30 degrees on the three-way valve of the boiler circuit, and 50 degrees at the outlet. Also note that the higher the temperature difference in the boiler, the higher the efficiency of the boiler. That is, a cooler coolant should flow into the boiler. Also, the greater the flow through the boiler, the higher the efficiency of the boiler. Thermal engineering testifies to it.

The flow through the boiler must be as high as possible for efficient heat exchange (efficiency is higher.).

A three-way valve at the outlet to the heat consumer is needed in order to stabilize the temperature of the consumer and prevent high temperatures from entering.

For example, from a real object:

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Modernization of the heating system in a private house may require the installation of two boilers at once, connecting them to a common network. What sequence should be followed in this case? How to connect two boilers into one system, which must be taken into account if there is a need to share gas with a solid fuel, electric boiler or liquid fuel heating equipment.

How to connect two boilers together?

I would like to clarify right away that simply connecting two boilers using different types of fuel to one system is one of the possible solutions lack of power problems installed equipment. It is also possible to connect more than two models to one network.

For what purposes may it be necessary to connect two boilers to one system? There are several compelling reasons to justify this.

Lack of power. Incorrect calculation of equipment or additionally attached living space can lead to the fact that the power of the boiler may simply not be enough to maintain the normal temperature of the coolant.
Increase functionality. It may be necessary to connect two boilers to one system in order, for example, to increase the time battery life equipment. For example, if the main source of heat is a solid fuel boiler, then for its operation it is necessary to constantly add firewood, which is not always convenient, and even more so practical.
By installing an electric boiler or a gas heater after it, this situation can be solved as follows. As soon as the firewood or coal burns out and the coolant begins to cool down, additional heating equipment is turned on in the process and continues to heat the room until the owner brings in a new batch of firewood in the morning.

As you can see, it is practical to connect two heating boilers using different types of fuel, in addition, it may be due to an urgent need associated with a lack of equipment performance.

How to connect two gas boilers in parallel

There are two schemes for connecting gas and any other water heating equipment. You can connect two boilers to one heating system:

Sequentially - in this case, one unit will be installed after another. In this case, the load will be distributed unevenly, since the main boiler will constantly work in full power, which can lead to its rapid failure.
Parallel. In this case, the heated area will be conditionally divided into two parts. Heating will be carried out immediately by two installed boilers. Parallel connection two gas-fired boilers are commonly used in cottage houses and buildings with a large heated area.

For parallel connection, it is mandatory to install a controller and also develop a cascade control scheme. Only a competent specialist in each case can answer the question of how to connect two gas boilers.

How to connect two boilers - gas and solid fuel?

Combining gas and solid fuel boilers into one system is a simpler task, for which it is necessary to take into account the main features that distinguish the operation of these two types of equipment.

Models of gas and solid fuel equipment can be installed sequentially in one network. In this case, TT boilers will play the role of the main source of heat supply.

The principle of their work will be that gas equipment will be turned on for heating only if the operation of the main unit for some reason becomes impossible. Also, usually the task of heating water is assigned to a gas boiler, of course, if such a function is provided. When designing such a system, these features must be taken into account.

It will also be necessary to coordinate the selected scheme in gas industry and get all the necessary permissions there, including specifications and connection project.

How to combine gas and liquid fuel boilers

For security reasons, for such a connection, it is necessary to create conditions under which it is possible safe work two types of equipment. To do this, do the following:

To carry out the installation of a general control system for the operation of water-heating equipment. Sharing a liquid-fuel and gas boiler involves the installation of general automation. It, in turn, is connected to control sensors, which give a signal to turn on in the event of a shutdown of the main heat source.
Install control valves. Shut-off valves operating in automatic mode can also be used.

The connection is made in series or in parallel, depending on the needs of the customer. Plan and circuit diagram are compiled in the design department, after which it is coordinated in the gas facilities service.

Advantages of installing several boilers in one network

Connect two boilers at the same time: floor and wall-mounted boilers may be needed if the area of the room as a result of construction works, increased sharply. Even if the equipment was originally purchased with a power reserve, it may not be enough for heating additional premises larger area. In this case, an additional boiler is installed, connected to the general heating system. The advantage of this solution is:

Ability to simultaneously control the operation of all equipment.
Savings due to the choice of the main type of fuel.
Possibility more long-term operation equipment.

Practice shows that it is possible to simultaneously install two or more boilers in one network. With each additional element, the overall performance and efficiency drops significantly. Therefore, the expediency of simultaneous installation of four or more units water heating technology completely missing.

The installation of a heating system in a private house begins with the installation of a boiler. In many suburban settlements there is no gas pipeline with natural gas. Instructions on how to properly connect a solid fuel boiler will alleviate this problem.

Necessary conditions for the correct connection of a solid fuel boiler to the heating system

The room for the boiler room is selected separately. An area of about 7m 2. Boiler room in a separate building perfect option. Loading fuel into the boiler room can be facilitated. Sufficient in the receiving hopper area with outer side where it will be unloaded, for example, coal, to mount the so-called estrus. Having unloaded the fuel into the receiving bunker, the coal is poured down the slope into the boiler house independently.
Position the heating boiler preferably below the 0 mark of the floor. This option installation of the boiler ensures ideal circulation of the coolant in the heating system without the use of a circulation pump.
The base for the boiler must be made of a concrete pad with an even top layer. Thickness concrete screed 10 cm. The base area under the boiler must be 20 cm larger than the dimensions of the connected boiler. From the side of the furnace 40-50 cm.
According to the norms of SNiP and fire requirements of the NPB, the distance between the boiler and the wall is 50 cm. From the side of the furnace hole, furnace, to the opposite wall, the distance is at least 1.3 m.
The installed heating boiler must not have gaps between the base and the body.
It is necessary to connect the boiler to the heating system with a steel pipe at least 1 meter long at the inlet and outlet of the pipeline. Connect the boiler to the heating system with copper and polymer pipes not properly.

The scheme is applied below correct connection solid fuel boiler.

There are many connection methods. Consider one of the simple and reliable ways to connect.

A safety group is installed from the boiler on a direct pipeline. After the safety group, a tee for the bypass is installed. Further, the supply is connected to the wiring of the heating system. Having given up its heat in the heating system, the coolant returns to the boiler through the return pipe. To avoid the main disease in the operation of solid fuel boilers, condensate, which adversely affects the integrity of the boiler, a thermostatic three-way valve is installed, connected to the return line on the bypass, set to a temperature of 50-60 ° C. When heated, the coolant circulates through a small circuit through a three-way valve. A temperature of 55°C prevents the formation of condensate on the inner walls of the boiler. After the three-way thermostatic valve is mounted circulation pump. As soon as the return temperature reaches 55 ° C, the three-way valve opens, and the heated coolant rushes into the heating circuit to the radiators.

Connecting a solid fuel boiler paired with a gas boiler, diagrams and features

The scheme for connecting a solid fuel boiler in parallel with a gas boiler differs from the installation of two solid fuel boilers. The requirements for the boiler room also differ, where the main condition is air exchange:

The area of a boiler room with a gas boiler, according to the recommendations of the fire authorities and the gas service, is calculated as follows: 1 kW of power - 0.2 m 3 with a ceiling height of 2.5 m, but not less than 15 m 3.
A boiler room with a gas boiler must be equipped with a window with a window, the size of which is 0.03 m 2 per 1 m 3 of the volume of the room.
The entrance door of the boiler room must go only to the street. Door width at least 80cm.

Gas boilers are available in two versions. Floor and wall. The requirements for installing a floor gas boiler are the same as for a solid fuel boiler. The length of the pipe connecting the chimney and the boiler is not more than 25 cm. If the boiler is coaxial, the pipe for the removal of combustion products is installed at an angle of -3 °. Otherwise, a separate pipe made of ceramic or lined with stainless steel with a hatch for removing combustion products is required for a gas boiler, and a tee with a tap for removing condensate is installed in the lower part of the pipe.

Gas and solid fuel boilers are connected in parallel to the heating system in several ways. The schemes are different, it is not necessary to know all of them, it is enough to understand the features that must be considered when using such a combination of boilers in relation to your room:

Efficient use of the heat exchanger. It will separate the open heating circuit and the closed one. Connect the boiler to one of the circuits, and connect the second boiler to the second circuit. A solid fuel boiler, capable of raising the temperature of the coolant to 115 ° C, heats the secondary closed circuit to which the gas boiler is connected. The gas boiler is adjusted to a temperature of about 50-60 ° C. The solid fuel boiler will take on the main load. As the fuel burns out, the gas boiler will automatically turn on, which heats the secondary circuit of the heat exchanger. The secondary circuit is equipped with a diaphragm expander. Closed expansion tank provides protection of radiators from excessive pressure. With such a scheme of a connected solid fuel boiler, it is possible to install an open expansion tank directly in the boiler room under the ceiling.
The use of a hydraulic switch for parallel connection of boilers is mainly used in houses with large area. The principle of operation of this system is as follows. The heating solid fuel boiler is installed first with a circulation pump, for example, 25/60 installed on the return pipe. On the pipe between the boiler and the pump is mounted solenoid valve MD regulating the operation of the boiler circulation. Mandatory installation of an adjusted safety valve in the supply line. Shut-off valves are not installed at the supply. The gas boiler is installed second. Through the tee, the boiler is connected through the supply pipe to the pipe from the solid fuel boiler and then connected to the hydraulic arrow. Shut-off valves are not installed on the arrow. On the second boiler, a pre-set safety valve. A closed expansion tank is installed from the hydraulic arrow on the return pipe to the tee. Then, through a tee on the pipe, it is connected first to the gas boiler with the installation of a circulation pump of less power than that of the first boiler. After the pump, a valve without a servomotor is installed. Further, a solid fuel boiler is connected from the tee on the return pipeline. The use of a collector after the hydraulic switch allows you to collect several heating circuits with pump groups on each of them. Collectors create the opportunity to configure each circuit individually according to the loads on the heating devices.
Another method of parallel connection of boilers, when a solid fuel heating unit is installed first, a gas one is installed second, and between them a flap valve is installed on the supply pipe, operating in the direction from the first heating unit. Before the non-return valve, a bypass is installed, connected to a three-way thermostatic valve set to a temperature of 55 ° C. Between the thermostatic valve and the boiler, a circulation pump of greater power than in a gas one is installed on the return pipeline. The gas boiler is connected through a tee on the supply pipeline to the solid fuel boiler and then the supply pipeline goes to the radiators. The return pipeline from the radiators through a tee is first connected to the gas boiler. After the tee, it is necessary to install a spring check valve at the boiler. If both boilers are working at the same time, you need to set temperature regime on boilers. The gas boiler is set to 45°C. The solid fuel boiler is adjusted to a temperature of 75-80°C. Priority will be given to solid fuel. In the process of fuel combustion and temperature decrease in the first boiler, the gas boiler will turn on automatically and will maintain the set temperature in the house.
The use of a buffer tank. The heat accumulator is a large steel insulated container, the task of which is to keep the heated coolant from the boiler. The maximum load occurs during the combustion of fuel in a solid fuel boiler. For effective work heating systems, the heat accumulator performs one of the main tasks. But there are big downsides to this scheme. To heat up the radiators desired temperature takes 2 to 4 hours. This is where the gas boiler plays its main role. Let's take a look at the installation diagram. The solid fuel boiler is tied in the traditional way. A safety group is installed in front of the bypass on the supply pipe. Then a bypass is installed through the tee. Further, the supply pipeline is connected to the storage tank. The bypass is connected to the return pipe through a thermostatic three-way valve set to 55°C. Then, a circulation pump is installed, working towards the boiler, and then the pipeline is connected to the boiler. A working circuit is created, and the coolant in the heat accumulator begins to gradually heat up. From the storage tank, the supply pipeline goes to heating appliances. A three-way valve is installed on it, going to the bypass. From the other outlet of the three-way valve, a circulation pump is mounted on the supply pipe.

After the pump, a flap valve is installed, working towards the radiators. Further, through the tee, the supply from the gas boiler is connected with the supply from the battery. After completing these works, the direct pipeline is connected to the distribution of the heating system. From the heating system, the return pipeline is connected through a tee to the gas boiler with the obligatory installation of a spring check valve operating towards the gas boiler. A closed expansion tank cuts in front of the tee, providing protection for the heating system. After the tee, through which the gas boiler is connected on the return, the return pipeline goes to the heat accumulator and is connected to the bypass from the supply pipeline also through the tee. After connecting to the bypass line, the return pipe is connected to the storage tank. This scheme allows you to quickly heat the heating system. Further operation of the system is designed for the priority of the operation of a solid fuel boiler.

Joint operation of a solid fuel boiler paired with an electric

The connection diagram of a solid fuel boiler in parallel with an electric boiler is described in detail and questions in the video:

Coordinated operation of solid fuel, gas and electric heating boilers

If desired, using a fairly simple connection scheme, you can combine the work of 3 or more various kinds heating boilers in addition to solid fuel, which still remains the most acceptable and economical in terms of the consumption of kindling resources.