Add to favorites

Modernization of the heating system of the admin building. Reconstruction of the heating system of an apartment building. Balancing heating systems

Hello dear Reader!

I want to tell you about what heating systems I had to deal with.

Some he exploited, some he assembled himself, including heating systems for private houses.

I learned a lot about their pros and cons, although, probably, not everything. As a result, for my house I did:

first, own scheme;
secondly, it is quite reliable;
thirdly, allowing modernization.

I suggest not to delve into the detailed study various schemes heating.

Let's look at them from the point of view of application in a private house.

After all, a private house can be for permanent residence, and temporary, like a dacha, for example.

So to speak, let's narrow our topic and get closer to practice.

About ten years, maybe I was wrong. I started servicing the first heating system 33 years ago, when I was a student at the Ural Polytechnic Institute. I was lucky to get a job in the institute's boiler room as a mechanic on duty. True, at that time I didn’t even think about what kind of system it was? Worked and everything.

The work was sometimes difficult when there was an accident. And if everything is fine - beauty, sit yourself and learn notes. Night on duty, in the morning to study, "to school", as we then said. Back on duty two nights later. And most importantly, they paid 110 - 120 rubles! At that time, young professionals received the same amount. Yes, plus a scholarship of 40 rubles. Gorgeous life! But, let's get closer to the heat.

From the name itself it is clear that heating occurs with heated air. The air is heated by a heat generator, and then it enters the premises through ducts. The cooled air is returned through the return channels for heating. Pretty comfortable system.

The first heat generator in history was a furnace. She heated the air, which diverged through the channels in the order of natural circulation. Such an air heating system was used in the past centuries in advanced city houses.

Now they use a variety of heat generators-boilers: gas, solid fuel, diesel, electric. In addition to natural circulation, forced circulation is also used. It is, of course, more efficient:

Firstly, it warms up the premises much faster;
Secondly, it has more high efficiency, since heat is removed from the heat generator much more efficiently;
Thirdly, it can be combined with the air conditioning system.

You probably already understood that here it doesn’t “smell” like a private house. Yes, that's right, for a private house this heating scheme is too cumbersome and expensive. Some calculations are worth something, and if you make a mistake, then it will be, as they say, fatal.

But let's not get upset. If you still want to be heated by air, there is a way out. This is a fireplace.

Moreover, in my opinion, not an ordinary firewood-eater fireplace, but a cast-iron fireplace insert shown in the figure above. it perfect option home cozy wood-fired heat generator. It is designed specifically for heating air, and not bricks, like a traditional fireplace.

The air enters the space under the fireplace (where the firewood lies for the entourage), flows around its heated body. Then flows around the red-hot chimney along the fireplace box and out through the holes in the top of the box. By the way, air ducts can be connected to these holes and hot air can be distributed throughout the premises.

Quite a worthy option, only if done with air ducts, then during construction you need to remember to put them in walls and ceilings. Someone also puts inflating, creating forced ventilation. But this, in my opinion, is overkill. By the fireplace, it is nice to hear the crackling of firewood, rather than the noise of a fan.

I think it is worth mentioning more fan heaters and heat guns. These are, so to speak, mobile air heating units. Very useful devices, especially when the main heating system is not working or you need to quickly “warm up” the air in the room. But, in my opinion, they cannot be considered as the main heating option.

So, a fireplace insert, as a source of air heating, is a good, and, moreover, a pleasant solution for a private house.

Water heating at home

In this case, the coolant is water or special liquids, for example, non-freezing. Here, the heat sources are also very different depending on the fuel. But if in the air system warm air comes into the room, then into the water air of the room heated by appliances who give him heat stored in water.

And the water stores a lot of heat. There is such a thing: "heat capacity", remember? If in your own words

The heat capacity of water is the amount of heat that must be transferred to water in order for its temperature to rise by one degree.

So this indicator near the water is very good. Look at the table on the right.

It turns out that we get a chic coolant almost for nothing.

Yes, the water system is somewhat more complicated, but it is also more flexible.

Imagine that heated water can be supplied through pipes anywhere and there it will give off the accumulated heat.

And the pipes can be easily hidden in the walls, or you can not hide them at all, modern ones look very aesthetically pleasing.

How does water give off heat? For this, several types of devices have been created:

Radiators - massive, for example cast iron, sections assembled into batteries.

Inside them flows hot water. They give off thermal energy mainly due to infrared radiation(radiation).

They are usually steel or aluminum, less often copper. The surrounding air, being heated by the convector, begins its natural upward movement. That is, a flow (convection) of air is created, which removes heat from the convector.

Modern aluminum appliances also belong to convectors, although they are called radiators. It should be noted that almost all thermal appliances water heating is called radiators, although strictly speaking, this is wrong. But let's not be smart.

Air is pumped through them to be heated. They are often used in supply ventilation systems to heat cold air entering from outside.

"Warm walls" - were used in the seventies in panel housing construction. AT concrete panels the serpentine was embedded in steel pipe, into which water was supplied from the heating system. I remember from childhood the warm walls of panel five-story buildings.

The water system can be successfully used in a private house. If this is a dacha, you can fill in a non-freezing coolant instead of water and not worry about defrosting the system.

Let's take a closer look at the options for heating systems for low-rise buildings.

Scheme of a gravity heating system

Why self-flowing? Because the water in it actually flows by itself. When heated in the boiler, the water rises, and then, gradually cooling in the radiators, flows down and returns to the boiler again. The system is simple, but the prerequisites must be observed:

The pipe should be pretty large diameter from 50 mm, and preferably 76 mm and more.
The pipe is laid with a slope to ensure the gravity flow of water.

Sometimes this same pipe heats the room without radiators and convectors due to its large mass and surface. Such pipes are called registers, they can be found at railway stations and bus stations of old small towns. It is now rarely used in private homes - it does not look very aesthetically pleasing. Imagine - there is a thick pipe in the room, and even an inclined one.

A very big advantage of this system is that it does not need a circulation pump, the water circulates itself. If the boiler is wood, coal or gas - no power outages are terrible, complete autonomy and independence. I'm talking about this because I myself have trouble with power outages.

A feature of a gravity-flow system, which is considered a disadvantage, is that it is open, that is, it communicates with air and there is no pressure in it. This means that an open expansion tank is needed and the water gradually evaporates, you need to monitor this. Of course, this is not a very serious drawback. I'm more repulsed by high sloping pipes.

For a private house, a closed heating system, in my opinion, is the best option. It's better to say closed. Closed means not in contact with air. Here are the new elements:

Membrane expansion tank to compensate for the expansion of water when heated;
Circulation pump for pumping water through the system;
Safety group - make-up valve (for adding water to the system in case of leakage), pressure gauge, safety valve(to release steam when water boils).

This is a more modern, aesthetic option. Radiators are used here, and more often aluminum convectors, thin metal-plastic or polypropylene pipes. There is no need to add water, think about the slope of the pipes, they can generally be hidden in walls or ceilings.

You can put beautiful aluminum or bimetallic radiators, a heated towel rail. I use two boilers in one system - an electric boiler and a water circuit for a fireplace insert. Like it worked out well.

Minus the system - without electricity for circulation pump she can't work. Moreover, if the firebox is “under steam” and the electricity is over, it can turn out to be a “boomsik” with the release of steam and a lot of noise. I know for myself. It looks like the pipes are being pounded with a hammer.

Therefore, the pump is connected to uninterruptible source(like a computer) so that there is time to safely cool the firebox. And the outlet of the safety valve is in the sewer.

Two-pipe heating system

There are two options for connecting radiators to the heating system:

The only plus of a single-pipe system is savings on pipes. But the minus is significant - the radiator closest to the boiler is the hottest, and the farthest is the coldest. And it’s also problematic to turn off some kind of radiator - they are all in the same circuit. If this is not critical, why not use this option? It's a perfectly normal pattern.

The two-pipe scheme is more flexible:

All radiators are almost equal. Water is supplied to each at the same temperature;
You can set your own temperature on each radiator by regulating the flow of water through it;
You can painlessly shut off the water supply to any radiator, for example, when it's hot or you need to flush the radiator;
More convenient for increasing the number of radiators.

Thus, in my opinion, a two-pipe scheme is more preferable.

For the sake of justice, it must be said that in the two-pipe version, the last radiator is somewhat “offended”, it gets less heat. The reason is that on it the pressure difference between supply and return is almost zero and the water flow is minimal.

So what choice did I make?

I installed an air-to-water heating system in my house. The fireplace is responsible for the air. Closed two-pipe water circuit includes an electric boiler, a water circuit for a fireplace insert and 40 aluminum radiator sections (6 radiators). 64 square meters of the first floor are heated in excess in any frost.

That's all for today. In the following articles I will bring to your attention the system gas heating, underfloor heating, infrared heating. Comment, ask questions. Thanks, see you!

The cost of tariffs for heat and hot water supply is "unaffordable" for most of our compatriots. And it's not just the desire of public utilities to get as much profit as possible. The reasons for this phenomenon are banal: the rise in the cost of hydrocarbons and the housing stock, most of which was built in the middle of the last century, when energy efficiency was not paid much attention to during construction. This publication will review measures to modernize the heating systems of residential buildings, which are already long time used in several European countries.

What does thermal modernization of a building mean?

Experts determine this concept, as a set of measures to bring an apartment building in line with modern energy efficiency standards. This includes measures related to reducing the heat loss of a building through walls, ceilings, roofs, basements, etc. Large heat losses occur due to low thermal performance and poor tightness of old windows and doors. In addition, thermal modernization affects the issues of re-equipment engineering systems(ventilation, heating, hot water), transition to combined (geothermal solar) sources of heat supply.

Important! Insulation of external fences, without re-equipment of heating and ventilation systems at home, is not effective and does not give a positive result (which often happens), and most often leads to an increase in energy costs by the consumer of utility resources.

A set of measures aimed at reducing heat consumption and improving the energy efficiency of buildings will be considered.

Insulation of enclosing structures

This activity can be divided into several important species works.

Insulation of external walls from the outside of the house.

Thermal insulation of enclosing structures is the application of an additional layer of material with a low coefficient of thermal conductivity to the walls. These measures make it possible to eliminate "cold bridges", increase the thermal insulation properties of walls, and effectively solve the problem of "material porosity". The following wall insulation technologies can be applied: seamless insulation system; creation of an insulating wall; arrangement of a ventilated facade.

Insulation of the roof, attic floors.

If the attic of the house is not heated, then work is carried out to insulate the floor under the attic with the protection of the insulating layer from mechanical damage.

Thermal insulation of floors above the basement.

This type of work is carried out from the basement side by gluing heat-insulating plates to the ceiling.

Advice! If it is impossible to carry out measures for thermal insulation of walls from the outside (an architectural monument, a complex relief of the facade, etc.), then it is necessary to insulate the outer walls from the inside of the building by laying polystyrene foam boards under plaster or drywall.

Reducing heat loss through windows

According to experts, up to 30% of the heat from heated rooms “leaves” through the windows. A radical way to solve this problem is to replace old wooden windows with energy-saving ones. It is enough to reduce their size, especially if the question concerns windows on stairwells. In most layouts of apartment buildings, there is an excess area for stair lighting. window openings, which causes large heat losses.

Modernization of the ventilation system

As you know, the most common way to organize air circulation in the premises of apartment buildings is natural ventilation. Air is removed through exhaust ducts located in kitchens and bathrooms. The influx of fresh air from the street is organized through natural leaks in windows and doors.

When replacing old windows with energy-efficient and airtight ones, the problem of heat loss is solved, but a new one appears: a sharp decrease in supply air. This problem is solved by modernizing the ventilation system, namely, by arranging ventilation with controlled air flow. In practice, this is solved by setting supply valves, windows with built-in hygro-dependent fans or installations of forced supply of fresh air to the premises.

Reconstruction of the heating system

Experts pay special attention to high heat consumption, which occurs due to the low efficiency of morally and technically obsolete home heating systems, which were not originally designed with excessive heat consumption. The main problems of old heating systems (CO) can be formulated as follows:

Poor or incorrect hydraulic balancing. This problem often associated with unauthorized intervention of residents in the structure heating system(installation of additional sections on radiators, replacement of batteries, pipelines, etc.)

Poor thermal insulation of heat supply pipes or its complete absence.

Structurally obsolete heat and distribution points.

Re-equipment of thermal units

Modernization of these facilities is a rather complicated and expensive process. Which includes the following changes:

Replacement elevator node heating systems to automated. In the case of connecting the house to the heat main according to an independent scheme, an automated individual heat point is installed; when using dependent, a scheme with a pumping admixture is used. Depending on the scheme used, all equipment must be weather-dependent and automatically stabilize the pressure in CO by regulating the supply of coolant.

Important! Replacing an outdated elevator assembly with an economizer will not allow the use of thermostats for heating radiators and balancing valves. The elevator simply "will not pull" additional hydraulic resistance, which will inevitably increase when using these devices.

Replacement of old heat exchangers with energy efficient ones.

Elimination of leaks in CO and replacement of valves.

Heating system balancing

Fortunately, the effectiveness of this event is no longer in doubt. The installation of balancing valves for a heating system on return risers with a limitation of the coolant temperature is a prerequisite for a competent modernization of CO, especially in houses with a large percentage of autonomous heating by gas boilers.

Installation of individual control devices

The installation of thermostats with an air temperature sensor on each battery, in addition to additional comfort for the residents of this building, will significantly reduce the consumption of thermal energy. The air temperature increased through the window openings (the sun warmed up), the thermostat reduced the amount of coolant for a specific heater.

Among the mandatory measures for the reconstruction of the heating system, carried out as part of the thermal modernization of the whole house, one can single out the installation of a common house heat supply metering unit and the transition to apartment heat metering. It is these measures that most stimulate residents to save.

Thermal modernization of an apartment building requires large financial costs. But in order to achieve significant savings by the end consumer (which means a return of money and profit for energy service investors), it is necessary to carry out comprehensive measures to reduce the amount of consumed thermal energy or thermal modernization.

A country house is the dream of every city dweller. This type of real estate has a lot of advantages over an apartment, ranging from the lack of noisy neighbors and ending with the picturesque surrounding landscapes. But one of the fundamental advantages of living outside the city is still the ability to choose and implement the most productive and inexpensive heating system.

The most common and popular heating scheme for a private cottage today is water heating with bottom wiring. Of course, since its inception a hundred years ago, it has undergone significant changes and modernization, acquired several modifications, and therefore there is plenty to choose from. Moreover, of all the existing schemes, it is the water one that differs most optimal combination parameters "price-effectiveness".

Home water heating systems: heat generators, features

The basis of the water heating scheme of a private house is a fuel unit - a boiler. As a rule, the choice of one or another type of heat generators is selected depending on the mass of parameters, including the personal preferences of property owners, the characteristics of the region and the availability of one or another type of fuel.

Often, all kinds of solid and liquid fuel units, gas or electrical devices. It should be noted that the most popular in our country are solid fuel and gas boilers, since fuel for them has the most affordable cost and, importantly, it is affordable - it is common in all regions.

In addition to the boiler itself, other elements are also used in the water heating of the house. So, for example, if the house has stove heating, then a variety of coils, registers and hollow built-in elements will help to upgrade it to water. In this case, the resulting circuit can already be called a combined one, distinguished by its simplicity and increased efficiency.

There is no fundamental difference in the procedure for installing the heating system, depending on the type of boiler. Simply follow the manufacturer's instructions.

In addition, due to the fact that water heating in a private house has a fairly versatile design, it is possible to install two or even three heat generators in parallel - this will achieve maximum performance, make the circuit completely autonomous, eliminate even the slightest risk of being left without heat in the cold room. winter time.

Advice. With such a parallel connection of boilers, it is important to consider the installation of a special automation system, which will help to ensure switching between units when one of the fuels stops supplying.

Water heating and natural circulation of the coolant

The most simple and affordable option water heating of a private house, which can be done without any problems and costs with your own hands. It cannot be said that the instruction for such a system does not imply any complex work for design and installation, implies the use of only available materials and accessories.

If we talk about the principle of operation, then water heating with natural circulation coolant, it is extremely simple. The water heated in the boiler rises up the pipeline (due to the difference in temperature differences), gradually entering all the radiators located around the house, while the cooled water returns to the heat generator again. Provided without the use of additional equipment.

Advice. When using a scheme with natural circulation of the coolant, it is important to ensure that the main pipelines are laid with a certain slope.
Often, 3-5 degrees per 1 running meter(about 10 mm).
Otherwise, the system will work, but the efficiency will be significantly reduced, which will lead to extra costs fuel.

The wiring can be done metal pipes different diameters - the choice depends on the characteristics of the boiler and radiators. A prerequisite can also be called a decrease in the cross section of the pipes towards the most extreme point of the heating circuit - the last radiator.

The pipe through which the water heated in the boiler is supplied to the system must be installed in such a way that its slope towards the radiators is maximum. The return point to the heat generator is made as low as possible in relation to the batteries - this is done for fast and efficient circulation of the coolant. This can be done by installing a thermal unit in the basement or basement.

Another integral attribute of a natural circulation water heating scheme is an expansion tank. Unlike a boiler, a similar unit is installed at the highest point of the cottage, the best option is the attic. It is possible to use hydroaccumulating tanks, but in this case it is important to ensure the installation of additional equipment, such as pressure gauges, air and safety valves.

Advice. Since in many houses the attic is not heated during the cold season, it is important to take care of the insulation of the expansion tank.
In this case, you can use heaters of various types, their choice in our time is extremely wide. The main requirement is impact resistance. high temperatures(up to 90C).

In addition to distributing water heating at home, plastic ones can also be used. Such pipes are easy to install, therefore, time installation work will be less.

Forced circulation in water heating systems

Another option for arranging heating country cottage- a scheme of water heating in a private house with forced circulation of the coolant. The main distinguishing feature is the presence of a special circulation pump.

The device allows you to achieve more efficient and high-quality pumping of water in the system, to ensure its supply even to the highest points of the house without loss of heat (especially good for cottages with two or three floors).

Unlike schemes with natural circulation, heating with forced movement of the coolant is not too demanding on the slope of the pipes. And the efficiency of such systems is almost 20-30% higher than that of those where water moves along highways through natural circulation.

With the forced movement of the coolant, hydroaccumulating tanks are used instead of traditional ones. Since the pressure in pipes and radiators can increase up to 1.5-2 atm, it is important to provide for the installation of special safety units: safety and air valves, pressure gauges, etc.

Shut-off valves must be located on both sides of the circulation pump, due to which it is possible to ensure that the coolant supply to the system is shut off.

The main types of water heating wiring

To date, there are several main options for piping around the house when using water heating:

Single pipe. The so-called "Leningrad", in which one pipe connects all the heaters in the house in the direction of the coolant. Such a scheme is chosen for simplicity, minimal financial (the price of highways is generally lower) and labor costs.

But at the same time, the heating of the radiators is uneven, and it is impossible to regulate the temperature in each of the batteries;

Two-pipe. The connection of heating radiators is made by two pipes laid parallel to the movement of water in the system.
The advantages include the ability to quickly adjust the temperature, quick and uniform heating of the premises, accessibility;
Collector arrangement of pipes. It has its own supply and return pipeline, connected together with the help of special distribution manifolds.
Feature - beautiful appearance, full control over all the batteries in the house from the switch cabinet.

The main advantages of water heating of the cottage

As you can see in the photo and video country houses on our website, water heating schemes are used quite often in our country.

There are many reasons for this widespread use:

The ability to perform installation work on the arrangement of home heating at any stage of construction. Moreover, even in finished house water heating is installed without any problems;

Water itself has excellent qualities when used as a heat transfer medium. High thermal conductivity, availability and low cost, along with unique heat capacity, make water the best choice;
Versatility, the ability to use different types of fuel to heat the coolant in the heating circuit;
Large selection of piping options in water heating schemes. You can choose a certain type depending on the mass of parameters, ranging from the area of \u200b\u200bthe cottage and ending with financial capabilities;
A variety of equipment for arranging home heating;
Accurate and quick adjustment of the air temperature in each of the rooms of a private house. It is provided by the installation of special equipment, namely temperature controllers and shut-off valves.

Conclusion

Today, there is simply no more affordable or effective alternative to water heating of a private house. It should be noted that every year more and more new heat generators, pipelines and radiators appear, due to which the efficiency of the scheme increases, while its cost decreases almost several times compared to other options.

A group of leading industry and academic institutions in the field of electric power industry (ENIN named after Krzhizhanovsky, VTI, etc.) developed the program "Modernization of thermal power plants for the period up to 2030". In the section "Heat supply and heat networks" of this document, targets are given that give an idea of the ways of modernization, the structure of heat production and some features of the construction of heat networks in the coming years.

The long-term forecast for the production and consumption of thermal energy takes into account the widespread implementation of measures to save heat transport: it is expected that until 2030, the production of thermal energy will increase annually by 0.35-0.6%, and consumption - by 0.9-1, one %. In other words, the difference between production and consumption (ie transport losses) will gradually decrease.

The total production of thermal energy in 2005 was 1977 million Gcal, and by 2020 this figure is expected to increase to 2000 million Gcal. The structure of production will not change significantly: in 2020, as in 2005, the main amount of thermal energy will be supplied to consumers by thermal power plants and large boiler houses (with a capacity of more than 20 Gcal/h). Significantly less, as at present, will be the share of autonomous heat sources, small boiler houses (less than 20 Gcal/h) and non-traditional heat sources.

Much attention in the subprogram "Modernization of thermal power plants" is paid to the issue of improving and increasing the reliability of thermal networks (see RCM No. 4 (14) 2012), the total length of which is Russian Federation already now is more than 172 thousand km. The main type of laying of heat networks (more than 90% of the total length) is underground laying in impassable and through channels. Not only today, but also in the future, channel laying will remain the main type of construction of heat pipelines. But preference in the modernization of heating networks will be given to industrial prefabricated structures.

When laying main pipelines, pre-insulated PPU (foam polymer urethane) pipelines with a system of operational remote control will be used. For heating networks with a diameter of up to 400 mm, preference will be given to pipelines in PPU or PPM (foam polymer-mineral) insulation, and for heating pipelines after the central heating station - flexible pipes Casaflex produced by the Polymerteplo Group or similar from other manufacturers. Flexible pipe systems made of of stainless steel in polyurethane foam insulation are designed for underground channelless laying of heating systems. Operating pressure such pipes - 1.6 MPa, working t - up to 160 °C (Fig. 1).

Fig.1

Isoproflex flexible pipes will be widely used for hot water pipelines. These are pipes made of cross-linked polyethylene in polyurethane foam insulation with a working temperature of 95 ° C and a maximum pressure of 1.0 MPa (Fig. 2).

Fig.2

For the production of pipes in industrial insulation, there are already more than 100 enterprises in almost all federal districts. The total production capacity of these enterprises is more than 10,000 km of pipes per year. But so far, the utilization of production capacities is from 30 to 60%.

On fig. Figure 3 shows pre-insulated polyurethane foam pipelines in a complete set, ready for installation, for channelless laying and in a galvanized sheath (Fig. 4) - for above-ground laying. The service life of heating mains with such pipelines increases to 30-40 years, and heat losses are reduced to 2%. It is clear that such a design of heat pipelines should significantly reduce fuel and electricity consumption. It is calculated that with a pipe diameter of 1020 mm, this reduction per 1 km of networks will be 0.106%, and with a diameter of 530 mm - already 0.217%. The temperature drop in the first case will be only 0.05 °C/km, in the second - 0.12 °C/km, and with a diameter of 219 mm - 0.46 °C/km.

Fig.3

Fig.4

The time of laying a heating main when using such heat pipelines is reduced by 3-4 times, capital costs are reduced by 15-20%, and repair costs are reduced by 3 times. But, perhaps, the most important advantage of such heating networks is that due to the mandatory installation of a system for operational remote monitoring of the dampening of thermal insulation (SODK), the accident rate of heating mains is practically eliminated.

MOEK - Moscow United Energy Company - can serve as an example of a responsible approach to solving the problem of reliability of heat pipelines. The investment project "Reconstruction of heating networks", launched by this company several years ago, involves the use of the latest technologies. These technologies can drastically reduce operating costs and extend the life of pipelines up to 30-40 years compared to 8-12 years when using traditional technologies. Special attention will be given to heat networks with pipes of small diameter, which account for 96% of all cases of damage to heat networks.

Posted on September 28, 2011 (valid until September 28, 2012)

The need for reconstruction of HVAC systems

The energy efficiency of new buildings is calculated already at the design stage. The decisions and measures that are taken are aimed at achieving a minimum energy consumption in the building. As a rule, these measures are set out in the national building regulations in each country. Of course, a lot of information about energy saving solutions and technologies can be found in the many available sources or technical seminars given by HVAC companies.

But the situation that occurs in old and not reconstructed buildings is much worse. These buildings are used great amount energy, because they were built using old technologies that did not provide adequate thermal insulation. As a result, large heat losses and increased energy consumption. The HVAC systems of these buildings are outdated, unbalanced and unsettled, therefore they are not able to provide a comfortable microclimate and consume excessive amounts of electrical and thermal energy.

Studies have confirmed that HVAC systems use over 60% of a building's total energy consumption. In the residential sector, the cost of energy used for heating is approximately 80% of the total costs. Therefore, during reconstruction, it is necessary to take into account not only work to improve the thermal insulation of facades, replace old windows with new ones, glaze balconies and loggias, but also complete renovation heating and ventilation systems.

Phases of reconstruction of heating systems

If there are financial and technical possibilities, it is recommended to completely reconstruct the old heating systems, while replacing the equipment at all stages: production (heating points, boiler houses), distribution (pipelines, control valves) and heat consumption (radiators, heaters, gas convectors, warm floors etc.). In this way, we can achieve the best energy saving readings. It is not always possible to carry out the reconstruction in full, but even with minimal improvements in the system, it is possible to increase its efficiency and at the same time provide the required comfort conditions in each room. In both cases, to achieve a result, hydraulic balancing of heating systems is indispensable.

Reconstruction of heating points

The most common heat generator for the heating system of a building is a heat point. Its purpose is to provide the necessary amount of heat, which depends on the surrounding climatic conditions and temperature chart systems, to the individual needs of the building from the centralized heating system. There are two types of heat points that are widely used, these are: thermal nodes without automatic control of the temperature of the coolant at the supply using an elevator or dependent substations with automatic temperature control (figure).

The main disadvantages of such systems:

*Maintaining the microclimate of the premises depends on heating networks.

*The quality of the heat carrier in the heating system depends on the district heating.

*There is no way to reduce energy consumption - these systems are not energy efficient.

*The building is hydraulic dependent.

*There are no pressure maintenance installations - while the static pressure in the system depends on the pressure in the heating network.

The best energy efficiency is achieved with a complete reconstruction of heating points, when the elevator dependent unit is replaced with an independent one with automatic temperature control (figure below).

It consists of a heat exchanger that separates the heating system of the building and the heating network, while ensuring its independent functioning.

In order to control and regulate the thermal energy of the building according to real needs, an installation is required. automatic system supply temperature control. It consists of a control valve which is controlled electric drive(picture on the left) by a signal from an electronic controller with temperature sensors. The weather-compensated control system detects changes in outside temperature as well as building heat consumption and automatically increases or decreases the total heat gain.

These systems can significantly reduce heating costs (but only if the heating system is balanced). In order to ensure fast, accurate and smooth control, as well as no problems with closing the control valve, it is recommended to install a differential pressure regulator (figure).

Since the heating system of the building becomes independent of the district heating network, it is necessary to ensure that it maintains a static pressure (figure below).

This function is performed by an expansion tank with a shut-off and drain valve for maintenance (figure below left), a make-up device and a pressure control module.

The safety valve in substations (figure on the right) is necessary to protect the weak links of the system from too much pressure when the pressure maintenance unit is in service or out of service.

The expansion tank is one of the most important elements of the heating system. When the coolant is heated to operating temperature, it expands, increasing its volume at the same time. If there is nowhere to place this additional amount of coolant, then the static pressure in the system will increase.

When, in this case, the maximum allowable pressure is reached, the safety valve will open and release the excess volume of the coolant, while reducing the static pressure of the system. In the absence of a safety valve or its incorrect selection and adjustment, too much pressure can damage consumers, pipes, connections and other elements of the system. If the safety valve opens too early or too often, it releases a significant amount of coolant from the system. At the same time, during the period when the system reduces its temperature regime (required less power heating or the system switches off when the heating season), the coolant is compressed and this leads to a decrease in static pressure. If the static pressure drops below the minimum required, a vacuum will be created in the upper sections of the system, which will lead to airing. Air in the hydraulic system interferes with normal circulation and can block flows in some areas, which leads to underheating of consumers and microclimate disturbance. Air is also additional reason noise in the system, and the oxygen that is in it causes corrosion of steel parts. At the same time, the lack of coolant in the system must be compensated with the help of make-up systems, which also entails additional costs and, without water treatment, brings new portions of air and new problems.

The task of the expansion tank is to constantly maintain the static pressure in the system between the minimum and maximum allowable values, taking into account the possible expansion or contraction of the coolant.

What makes an expansion tank reliable?

The expansion tank is one of the most important elements in system. Therefore, it is important to know what exactly ensures its proper functioning, reliability and long term services.

A high-quality and reliable tank should have the following design. It consists of a special rubber bag placed inside a steel vessel. This bag allows you to place the excess volume of coolant formed during heating and, as a result, expansion. When the temperature drops, the tank returns the required amount of coolant back to the system. Air is forced into the pressure vessel, which acts on the rubber bag with the coolant, thus allowing the necessary pressure to be maintained in the system.

Below are the technical specifications that describe the quality of the expansion tank:

* Tight design to maintain a constant volume of compressed air and high-quality operation of the expansion tank over many years of operation. This is only possible thanks to the fully welded construction of the steel vessel.

*Maximum density of the rubber bag to prevent diffusion of compressed air from the air chamber through the bag into the coolant, which can create pressure and corrosion problems. The highest protection against diffusion is offered by Pneumatex bags made of butyl rubber. Butyl rubber is the rubber with the highest airtightness of any known type of rubber elastomer. For this reason, butyl rubber is used to produce car tires.

* Reliability of connection of a rubber bag and a steel vessel. The problem with simple expansion tanks is that the membrane is damaged in the place where it is connected to the walls of the steel vessel, due to its frequent movement and stretching. To avoid this problem, the connection of the bag to the vessel should be as small as possible and the stretch at the junction as small as possible.

* The heating medium must not be in contact with the steel vessel to prevent corrosion inside the expansion tank. Tanks where water enters the rubber bag are corrosion resistant.

Reconstruction of the heating system

Reconstruction of heat substations is only one of the main phases in a complete renovation of the heating system. At the same time, if you make minimal changes and only in one section of the system, the energy-saving effect may not be fully achieved. So what do we still need to do to ensure that the heating system is reliable with the minimum required energy consumption?

In old buildings existing systems heating, as a rule, have a single-pipe type of radiator connection without a device for monitoring and controlling the temperature in the room (figure). Its main disadvantages are:

* Constant consumption - the maximum consumption of thermal energy without the possibility of changing the required thermal load.

* Lack of individual room temperature control.

* Systems are not balanced - they have problems with the correct distribution of flows.

* Old and often emergency pipes, fittings, radiators and other equipment.

* Lots of air in the system - leading to corrosion, sludge, extra noise and reduced heating system performance.

* Problems with static pressure.

* The required level of indoor comfort has not been achieved and is not properly maintained.

Individual room temperature control.

For the human body, providing comfort requires a certain temperature in the room, while it must be constantly maintained and not changed. This temperature depends on a number of factors - heat gain from heating devices (radiators), additional sources heat (solar energy, people, electricity and Appliances, heating during cooking) and heat loss, which depends on the outdoor temperature, windiness, geographic location and orientation of the building, its design, insulation, etc.

In rooms where the temperature is not automatically controlled, there is no way to use these additional heat inputs and thus reduce the energy costs that are delivered by the building's heating system. This usually leads to overheating of the premises, while excess heat is released through open windows. All this ultimately leads to high energy and financial costs.

In older systems, the heating medium flow is always constant and there is no way to minimize the heating costs and the energy consumption of the pumps when only a small part of the heat energy is required for the rooms.

To ensure the best energy efficiency, it is recommended to replace old systems with new ones with a two-pipe wiring and automatic control room temperature (pictured below). If it is not possible to switch to a two-pipe scheme, then it is necessary to install automatic temperature control devices in the room. In this case, the systems must be hydraulically balanced.

To ensure the correct individual control of the room temperature, it is necessary to replace the old radiators with more efficient new ones, while installing on each radiator thermostatic valve(pictures on the right and left) with a thermostatic head, which will allow you to control the heat transfer of the radiator into the room.

In the case of a one-pipe system, one option for individual control of the room temperature can be the use of low resistance thermostatic valves (figure 1) or three-way thermostatic valves (figure 2).

figure 1 figure 2

The thermostatic valve with thermostatic head will automatically maintain the temperature within the range of the preset setting. The thermal head has a scale, where each sign corresponds to the value of the maintained temperature in the room.

Some manufacturers display this information directly on the thermostatic head housing. When the actual room temperature more than required, the liquid in the thermal head expands and begins to close the thermostatic valve, thus reducing the coolant flow through the radiator. The radiator power is reduced and the room temperature becomes correct. When the temperature drops, the thermostat reacts in the opposite way, opening the valve, allowing you to increase the radiator power and raise the temperature to the set value (figure below).

At the same time, radiators receive only the amount of energy that is required to ensure comfort in each a specific room, while the thermal energy of the entire system is efficiently used. The level of comfort and energy savings depend on the quality of the thermal head. The more precise, stable and reliable the thermostatic head, the more heat energy is saved. Thermal heads can be of different types and purposes. For example, the Heimeier type K thermostatic head (figure 3) is ideal for temperature control in rooms in residential buildings. For schools, kindergartens, offices and other public buildings, it is recommended to use thermostatic heads K with anti-theft protection or heads type B with a higher degree of protection (figure 4). In buildings with high hygiene requirements, the use of a DX thermal head (figure 5), which has hygiene certificates, is recommended.

But the main condition in order to have high-quality maintenance and control of temperature in each individual room is the obligatory balancing of the heating system.

figure 3 figure 4 figure 5

Balancing of heating systems.

Another big problem in old systems is excess heat (overheating) in some rooms and its lack (underheating) in others. Usually, those rooms that are close to the heating point are overheated, and the farther from the IHS, the colder. Such systems use a large number of energy.

The reason for this problem is the incorrect distribution of the coolant in the system, due to its hydraulic imbalance. What flow will be in each section of the system depends on the hydraulic resistance of this section. This resistance has changed in old systems due to corrosion and clogging of pipes, dirt accumulation, repair or reconstruction, when consumers are replaced, etc.

In older systems, devices for balancing were not provided. It was not possible to carry out balancing for the reason that at that time they did not know how to do it. The problems that appeared due to the imbalance of the system were solved in other but not always successful ways.

One of possible solutions, to eliminate problems in underheated rooms, is to increase the power of the pumps. This leads to the fact that in these rooms it will become warmer, but rooms that already received too much heat will become increasingly overheated and the residents or tenants are forced to release excess heat through open windows. In addition, as the power of the pumps increases, their energy consumption increases.

The second solution may be to increase the temperature of the coolant. But in this case, a similar situation occurs with overheating of part of the premises with a significant increase in heating costs.

The main goal of balancing heating systems is to provide all sections of the system with the necessary amount of thermal energy under design (worst) conditions, when the outside temperature is as low as possible. At the same time, under all other conditions, the system will work as expected.

It is important that after balancing the system, the minimum required amount of heat and electricity is used.

To achieve this goal, three main tools are needed - these are balancing valves with the ability to accurately measure, measuring instruments and balancing methods.

How accurately you can measure on balancing valves, and what methods you use, determines the result of balancing.

The balancing valve is a Y-type valve with an adjustable preset that allows the flow to be limited, clearly indicated by a scale on the handle, with two self-sealing measuring nipples for measuring differential pressure, flow and temperature (figure).

The valve is called Y-type because the control cone, in this case, is at an optimal angle to the direction of flow through the valve. This design is essential for better accuracy and minimizes the effect of water flow on measurements.

The balancing valve acts as a shut-off valve and can also be used for drainage. To perform high-quality balancing, the valves must be selected right size and installed in accordance with the rules. All this should be provided by the heating system design engineer.

A special device is used to measure the flow, pressure drop and temperature on the installed balancing valves, as well as apply methods for balancing the system (figure).

It is a multifunctional computer device with very precise sensors and integrated measurement, balancing and debugging functions, optional hydraulic calculator and more. useful features, which help to quickly and accurately set up the system. The balancing device can be associated with a special software to update and download data from a PC or send balance results to a PC.

But using only balancing valves and a measuring instrument is not enough. You must know what and how to do with them. Otherwise, the process of setting up the heating system for correct work, which will provide a comfortable microclimate and minimal energy consumption, will seem like a nightmare. How then to balance this system? You need to apply the technique!

First of all, the hydraulic system must be divided into separate parts (hydraulic modules), with the help of so-called "partner valves".

The next stage is to balance all hydraulic modules using TA methods, from consumers, branches, risers, mains, collectors to heating points. When using the method, all balancing valves of this system and the sections in which they are installed will achieve the design flow rate of the coolant, while creating minimal pressure losses on the valves.

After that, when the entire system is balanced with minimal pressure loss, switch the pump to the minimum required speed for this system (if the system is not balanced, the pump usually runs at maximum) and adjust the total flow of the system on the main partner valve located at the pump. As a result, the pump will use a minimum amount of energy, and the thermal energy required to heat the coolant to the appropriate temperature will be efficiently used. Upon completion of the balancing work, the client receives a balancing report, which indicates the required and actually achieved flow rates and the settings of the balancing valves. This is a document that confirms the balance of the system and ensures that it works as expected by the project.

Highly important function balancing valves is the ability to diagnose the system. Once a system is up and running, it is very difficult to determine its actual performance and efficiency if there is no way to measure it. Using balancing valves with measuring nipples, it is possible to detect malfunctions in the system, find out its real state, characteristics and accept right decisions in case of problems. Diagnostics allows you to detect various errors, the causes of failures and promptly eliminate them before it is too late.

Air and sludge separators in heating systems.

In order to be able to balance the system, it must be clean and without air. Very often, problems in the system appear due to air ingress and corrosion. Air acts as thermal insulation: where there is air, there is no coolant and heat is not transferred from the hydraulic system to the room. Air bubbles can stick to the inside walls of the heatsink, reducing heat dissipation. Due to air pockets in the upper part of the system and in consumers, the flow in them may decrease or even stop completely. At the same time, the rooms will no longer be heated. When a large amount of air circulates in the system, noise appears in radiators, pipes, valves.

We know that air is a mixture of gases. It contains 78% nitrogen and 21% oxygen. Therefore, when air enters the system, oxygen will also be in it and react with water and metals, causing corrosion.

Corrosion not only destroys the equipment, thus reducing the life of the system, but also reduces its thermal efficiency and efficiency. Rust, as a product of corrosion, is formed in layers in the heat exchangers of boilers, radiators, pipes inside, while reducing their heat transfer, and also increases their hydraulic resistance. When rust circulates along with the flow, it accumulates in different parts of the system (pipes, valves, consumers, pumps, filters, etc.) (figure). In this case, it can limit the flow or block it.

But how can air appear in completely closed and hermetic heating systems?

There are several main possibilities. The first possibility is that air enters the system by naturally dissolving in water, which is used to fill or recharge the system. When heated, the temperature of the water rises and dissolved air is released from it as a free gas, causing the above problems in doing so. The more water is heated, the more air comes out of it.

The second possibility is insufficient static pressure. If the expansion tank is of poor quality, its casing, membrane or bag is not strong enough, after a while compressed air will enter the environment or system. In this case, the pressure in the air part of the expansion tank will drop or disappear altogether. The tank will be completely filled with water, and a vacuum will be created in the upper part of the system.

Heating systems are tight for liquid and exclude its leakage, but not for air. Through automatic air vents, rubber gaskets and other connections, air will enter the system. A large amount of it may appear during service work, as well as when the system is stopped and idle.

To prevent the above problems, in addition to high-quality expansion tanks, it is recommended to install air separators (microbubble separators) (Figure 1) or vacuum deaerators.

The separator in a short period will collect free air circulating with the flow and remove it from the system. To remove free air from pockets in the upper parts of the system, automatic air vents with no leakage are recommended (effective in the absence of circulation). They provide simple and fast filling and emptying the system (Figure 2).

Sludge or dirt in the system can be removed using sludge separators (figure 3). These devices allow you to collect everything, even the smallest particles, dirt and rust in a special chamber at the bottom of the case.

The task of the maintenance staff will only be to open the drain cock to flush the separator from time to time. Cleaning the coolant, the sludge separators do not become clogged and do not restrict circulation. It does not require a system shutdown to clear them.

figure 1 figure 2 figure 3

Results

Increasing every year energy consumption and waste emissions are one of the biggest problems in the whole world. They have big influence on our environment, quality of life, ecology, climate change and economy. This impact can be minimized if we make our buildings, which use more than 40% of all energy produced, much more energy efficient.

One way is to renovate old HVAC systems that use more than 60% of all the energy needed for a building. The main objectives of the reconstruction should be: replacement of old system elements with more efficient new ones, application of energy-saving solutions and technologies, high-quality balancing of systems, air removal, cleaning, pressure maintenance and individual temperature control in each room.