What is a hot water heating system?

Why the riser is hot and the batteries are cold

Sometimes, with hot supply, the return of the heating battery remains cold. There are several main reasons for this:

incorrect installation;
the system or one of the risers of a separate radiator is aired;
insufficient fluid flow;
the cross section of the pipe through which the coolant is supplied has decreased;
the heating circuit is dirty.

Cold return is a serious problem that must be fixed. It entails many unpleasant consequences: the temperature in the room does not reach the desired level, the efficiency of radiators decreases, there is no way to correct the situation with additional devices. As a result, the heating system does not work as it should.

The main trouble with cold return is the large temperature difference that occurs between the supply and return temperatures. In this case, condensate appears on the walls of the boiler, reacting with carbon dioxide, which is released during the combustion of fuel. As a result, acid is formed that corrodes the walls of the boiler and reduces its service life.

What is harmful to the high return temperature in the heating system

A little more difficult with solid fuel devices, they do not regulate the heating of the liquid, and can easily turn it into steam. And it is impossible to reduce the heat from coal or wood by turning the knob in such a situation. At the same time, the control of heating of the coolant is rather conditional with high errors and is performed by rotary thermostats and mechanical dampers.

Electric boilers allow you to smoothly adjust the heating of the coolant from 30 to 90 ° C. They are equipped with an excellent overheating protection system. One-pipe and two-pipe lines The design features of a one-pipe and two-pipe heating network cause different standards for heating the coolant. For example, for a single-pipe line, the maximum rate is 105 ° C, and for a two-pipe line - 95 ° C, while the difference between the return and supply should be, respectively: 105 - 70 ° C and 95 - 70 ° C.

1 Temperature standards
2 Optimum values in an individual heating system
3 One-pipe and two-pipe lines
4 Matching the temperature of the heating medium and the boiler
5 Ways to Reduce Heat Loss

Temperature standards Requirements for the temperature of the coolant are set out in regulatory documents that establish the design, installation and use of engineering systems of residential and public buildings. They are described in the State building codes and regulations:

DBN (V.

It entails many unpleasant consequences: the temperature in the room does not reach the desired level, the efficiency of radiators decreases, there is no way to correct the situation with additional devices. As a result, the heating system does not work as it should. The main trouble with cold return is the large temperature difference that occurs between the supply and return temperatures.

In this case, condensate appears on the walls of the boiler, reacting with carbon dioxide, which is released during the combustion of fuel. As a result, acid is formed that corrodes the walls of the boiler and reduces its service life. 3 How to make radiators hot - looking for solutions If it is found that the return is too cold, a series of troubleshooting steps should be taken. First of all, you need to check the correct connection.

Heat meters

Let us recall once again that the heat supply network of an apartment building is equipped with heat energy metering units that record both the consumed gigacalories and the cubic capacity of water passed through the house line.

In order not to be surprised by bills containing unrealistic amounts for heat at temperatures in the apartment below the norm, before the start of the heating season, check with the management company whether the meter is in working order, whether the verification schedule has been violated.

Most city apartments are connected to the central heating network. The main source of heat in large cities is usually boilers and CHPs. A coolant is used to provide heat in the house. Typically, this is water. It is heated to a certain temperature and fed into the heating system. But the temperature in the heating system can be different and is related to the temperature indicators of the outside air.

To effectively provide city apartments with heat, regulation is necessary. The temperature chart helps to observe the set heating mode. What is the heating temperature chart, what types of it are, where is it used and how to compile it - the article will tell about all this.

Under the temperature graph is understood a graph that shows the required mode of water temperature in the heat supply system, depending on the level of outdoor temperature. Most often, the heating temperature schedule is determined for central heating. According to this schedule, heat is supplied to city apartments and other objects that are used by people. This schedule allows you to maintain the optimum temperature and save heating resources.

Heating battery return cold device, causes, remedies

If the connection is not made correctly, the downpipe will be hot, but should be slightly warm. Pipes should be connected according to the diagram. Sometimes it may be necessary to dismantle the control valve to increase the cross section. In order to avoid air locks that prevent the coolant from moving, it is necessary to provide for the installation of a Mayevsky valve or a bleeder for air removal. Before venting, turn off the supply, open the tap and let the air out.

Then the tap is closed, and the heating valves open. Often the cause of the cold return is the control valve: the cross section is narrowed. In this case, the crane must be dismantled and the cross section increased using a special tool.

But it is better to buy a new faucet and replace it. The reason may be clogged pipes. It is necessary to check them for patency, remove dirt, deposits, clean well.

degrees here and there

Water for the heating configuration is prepared at a CHP plant or in a boiler house. The norms of water temperature in the heating system are prescribed in the building rules: the component must be heated to 130-150 ° C.

The supply is calculated taking into account the parameters of the outside air. So, for the South Ural region, minus 32 degrees is taken into account.

To prevent the liquid from boiling, it must be supplied to the network under a pressure of 6-10 kgf. But this is a theory. In fact, most networks operate at 95-110 ° C, since the network pipes of most settlements are worn out and high pressure will tear them like a heating pad.

A loose concept is the norm. The temperature in the apartment is never equal to the primary indicator of the heat carrier. Here, the elevator unit performs an energy-saving function - a jumper between the direct and return pipes. The norms for the temperature of the coolant in the heating system on the return in winter allow the preservation of heat at a level of 60 ° C.

The liquid from the straight pipe enters the elevator nozzle, mixes with return water and again goes into the house network for heating. The carrier temperature is lowered by mixing the return flow. What affects the calculation of the amount of heat consumed by residential and utility rooms.

Why is it better to use antifreeze in the heating system, rather than water

Antifreeze liquid (or antifreeze) in the heating system greatly simplifies the work with the equipment.If you use ordinary water as a coolant, then the heating system has to be equipped with additional devices, such as a tap to bleed air from the expansion tank. In addition, in the variant of a country house that is not constantly used, water will have to be drained or filled into the heating system at each visit, otherwise it will simply freeze in winter.

On the one hand, water has a higher heat capacity and, when moving through the pipelines of the heating system, retains heat longer. This is what causes the wider use of water as a coolant in private country houses.

Central heating

How the elevator assembly works

At the entrance of the elevator there are valves that cut it off from the heating main. On their closest flanges to the wall of the house, there is a division of areas of responsibility between residents and heat suppliers. The second pair of valves cuts off the elevator from the house.

The supply pipeline is always at the top, the return line is at the bottom. The heart of the elevator assembly is the mixing assembly, in which the nozzle is located. A jet of hotter water from the supply pipeline flows into the water from the return, involving it in a repeated circulation cycle through the heating circuit.

By adjusting the diameter of the hole in the nozzle, you can change the temperature of the mixture entering the .

Strictly speaking, the elevator is not a room with pipes, but this node. In it, water from the supply is mixed with water from the return pipeline.

What is the difference between the supply and return pipelines of the route

In normal operation, it is about 2-2.5 atmospheres. Typically, 6-7 kgf / cm2 enters the house at the supply and 3.5-4.5 at the return.

What is the difference in the heating system

The difference on the highway and the difference in the heating system are two completely different things. If the return pressure before and after the elevator does not differ, then instead of supplying the house, a mixture enters, the pressure of which exceeds the readings of the pressure gauge on the return line by only 0.2-0.3 kgf / cm2. This corresponds to a height difference of 2-3 meters.

This difference is spent on overcoming the hydraulic resistance of spills, risers and heaters. The resistance is determined by the diameter of the channels through which the water moves.

What diameter should be risers, fillings and connections to radiators in an apartment building

The exact values are determined by hydraulic calculation.

In most modern houses, the following sections are used:

Heating spills are made from pipes DU50 - DU80.
For risers, a pipe DN20 - DU25 is used.
The connection to the radiator is made either equal to the diameter of the riser, or one step thinner.

What is a hot water heating system?

In the photo - a more sensible solution. The diameter of the eyeliner is not underestimated.

What to do if the return temperature is too low

In such cases:

Reaming nozzle
. Its new diameter is agreed with the heat supplier. The increased diameter will not only raise the temperature of the mixture, it will also increase the drop. The circulation through the heating circuit will be accelerated.
In case of a catastrophic lack of heat, the elevator is disassembled, the nozzle is removed, and the suction (pipe connecting the supply to the return) is suppressed
.
The heating system receives water from the supply pipeline directly. The temperature and pressure drop increase sharply.

What to do if the return temperature is too high

The standard measure is to weld the nozzle and drill it again, with a smaller diameter.
When an urgent solution is needed without stopping the heating, the differential at the elevator inlet is reduced with the help of shutoff valves. This can be done with an inlet valve on the return, controlling the process with a pressure gauge. This solution has three disadvantages:
- The pressure in the heating system will increase. We're limiting the outflow of water; the lower pressure in the system will become closer to the supply pressure.
- The wear of the cheeks and the valve stem will accelerate sharply: they will be in a turbulent flow of hot water with suspensions.
- There is always a chance of falling worn cheeks.If they completely shut off the water, the heating (primarily the access one) will be defrosted within two to three hours.

Why do you need a lot of pressure in the track

Indeed, in private houses with autonomous heating systems, an overpressure of only 1.5 atmospheres is used. And, of course, more pressure means more money for stronger pipes and more power for the boost pumps.

The need for more pressure is associated with the number of storeys of apartment buildings. Yes, a minimum drop is needed for circulation; but after all, the water must be raised to the level of the jumper between the risers. Each atmosphere of excess pressure corresponds to a water column of 10 meters.

Knowing the pressure in the line, it is easy to calculate the maximum height of the house, which can be heated without the use of additional pumps. The calculation instruction is simple: 10 meters are multiplied by the return pressure. The pressure of the return pipeline of 4.5 kgf / cm2 corresponds to a water column of 45 meters, which, with a height of one floor of 3 meters, will give us 15 floors.

By the way, hot water is supplied in apartment buildings from the same elevator - from the supply (at a water temperature not higher than 90 C) or the return. With a lack of pressure, the upper floors will remain without water.

The device of the heating system what is the return

The heating system consists of an expansion tank, batteries, and a heating boiler. All components are interconnected in a circuit. A fluid is poured into the system - a coolant. The fluid used is water or antifreeze. If the installation is done correctly, the liquid is heated in the boiler and begins to rise through the pipes. When heated, the liquid increases in volume, the excess enters the expansion tank.

Since the heating system is completely filled with liquid, the hot coolant displaces the cold one, which returns to the boiler, where it heats up. Gradually, the temperature of the coolant increases to the required temperature, heating the radiators. The circulation of the liquid can be natural, called gravity, and forced - with the help of a pump.

Batteries can be connected in three ways:

1.
Bottom connection.
2.
diagonal connection.
3.
Side connection.

In the first method, the coolant is supplied and the return is removed at the bottom of the battery. This method is advisable to use when the pipeline is located under the floor or baseboards. With a diagonal connection, the coolant is supplied from above, the return is discharged from the opposite side from below. This connection is best used for batteries with a large number of sections. The most popular way is side connection. Hot liquid is connected from above, the return flow is carried out from the bottom of the radiator on the same side where the coolant is supplied.

Heating systems differ in the way pipes are laid. They can be laid in one-pipe and two-pipe way. The most popular is the single-pipe wiring diagram. Most often it is installed in multi-storey buildings. It has the following advantages:

a small number of pipes;
low cost;
ease of installation;
serial connection of radiators does not require the organization of a separate riser for draining liquid.

For the organization of individual heating, a two-pipe piping scheme is used. Hot feed is carried out through one pipe. On the second, the cooled water or antifreeze is returned to the boiler. This scheme makes it possible to connect radiators in parallel, ensuring uniform heating of all devices.In addition, the two-pipe circuit allows you to adjust the heating temperature of each heater separately. The disadvantage is the complexity of installation and the high consumption of materials.

Features of scheduling

The temperature graph indicators are developed based on the capabilities of the heating system, the heating boiler, and temperature fluctuations in the street. By creating a temperature balance, you can use the system more carefully, which means it will last much longer. Indeed, depending on the materials of the pipes, the fuel used, not all devices are always able to withstand sudden temperature changes.

When choosing the optimal temperature, they are usually guided by the following factors:

It should be noted that the temperature of the water in the central heating batteries should be such that it will warm the building well. Different standards have been developed for different rooms.
For example, for a residential apartment, the air temperature should not be less than +18 degrees. In kindergartens and hospitals, this figure is higher: +21 degrees.

When the temperature of the heating batteries in the apartment is low and does not allow the room to warm up to +18 degrees, the owner of the apartment has the right to contact the utility service to increase the efficiency of heating.

Since the temperature in the room depends on the season and climatic features, the temperature standard for heating batteries may be different. Heating of water in the heat supply system of the building can vary from +30 to +90 degrees. When the temperature of the water in the heating system is above +90 degrees, then the decomposition of the paintwork and dust begins. Therefore, above this mark, heating the coolant is prohibited by sanitary standards.

It must be said that the calculated outdoor air temperature for heating design depends on the diameter of the distributing pipelines, the size of the heating devices and the coolant flow in the heating system. There is a special table of heating temperatures that facilitates the calculation of the schedule.

The optimal temperature in the heating batteries, the norms of which are set according to the heating temperature chart, allows you to create comfortable living conditions. You can find out more about bimetallic heating radiators.

The temperature schedule is set for each heating system.

Thanks to him, the temperature in the home is maintained at an optimal level. Graphs may vary. Many factors are taken into account in their development. Any schedule before being put into practice needs to be approved by the authorized institution of the city.

In this article I want to tell you how and on the basis of what the temperature of the coolant is regulated. I don't think that this article will be useful or interesting to heat power workers, since they won't learn anything new from it. But for ordinary citizens, I hope it will be useful.

The temperature schedule is developed for each city, depending on local conditions. It clearly defines what should be the temperature of the network water in the heating network at a specific outdoor temperature. For example, at -35 ° the temperature of the coolant should be 130/70. The first digit determines the temperature in the supply pipe, the second - in the return. The heat network manager sets this temperature for all heat sources (CHP, boiler houses).

The rules allow deviations from the given parameters:

Each heating system has certain characteristics. These include power, heat transfer and temperature operation. They determine the efficiency of work, directly affecting the comfort of living in the house. How to choose the right temperature graph and heating mode, its calculation?

Changes in heating design

Replacement of existing heating devices in the apartment is carried out with the obligatory coordination with the management company.Unauthorized change in the elements of warming radiation can disrupt the thermal and hydraulic balance of the structure.

The heating season will begin, a change in the temperature regime in other apartments and sites will be recorded. A technical inspection of the premises will reveal unauthorized changes in the types of heating devices, their number and size. The chain is inevitable: conflict - court - fine.

So the situation is resolved like this:

if not old ones are replaced with new radiators of the same size, then this is done without additional approvals; the only thing to apply to the Criminal Code is to turn off the riser for the duration of the repair;
if new products differ significantly from those installed during construction, then it is useful to interact with the management company.

Heating system

Why do you need an expansion tank

Accommodates excess expanded coolant when it is heated. Without an expansion tank, the pressure can exceed the tensile strength of the pipe. The tank consists of a steel barrel and a rubber membrane that separates air from water.

Air, unlike liquids, is highly compressible; with an increase in the volume of the coolant by 5%, the pressure in the circuit due to the air tank will increase slightly.

The volume of the tank is usually taken to be approximately equal to 10% of the total volume of the heating system. The price of this device is low, so the purchase will not be ruinous.

Proper installation of the tank - eyeliner up. Then no more air will get into it.

Why does pressure decrease in a closed circuit?

Why does pressure drop in a closed heating system?

After all, the water has nowhere to go!

If there are automatic air vents in the system, the air dissolved in the water at the time of filling will exit through them.
Yes, it is a small part of the coolant volume; but after all, a large change in volume is not necessary for the pressure gauge to note the changes.
Plastic and metal-plastic pipes can be slightly deformed under the influence of pressure. In combination with high water temperature, this process will accelerate.
In the heating system, the pressure drops when the temperature of the coolant decreases. Thermal expansion, remember?
Finally, minor leaks are easy to see only in centralized heating by rusty traces. The water in a closed circuit is not so rich in iron, and the pipes in a private house are most often not steel; therefore, it is almost impossible to see traces of small leaks if the water has time to evaporate.

What is the danger of a pressure drop in a closed circuit

Boiler failure. In older models without thermal control - up to the explosion. In modern older models, there is often automatic control of not only temperature, but also pressure: when it falls below the threshold value, the boiler reports a problem.

In any case, it is better to maintain the pressure in the circuit at about one and a half atmospheres.

How to slow down the pressure drop

In order not to feed the heating system over and over again every day, a simple measure will help: put a second larger expansion tank.

The internal volumes of several tanks are summarized; the greater the total amount of air in them, the smaller the pressure drop will cause a decrease in the volume of the coolant by, say, 10 milliliters per day.

Where to put the expansion tank

In general, there is no big difference for a membrane tank: it can be connected to any part of the circuit. Manufacturers, however, recommend connecting it where the water flow is as close to laminar as possible. If there is a tank in the system, it can be mounted on a straight pipe section in front of it.

Choice of consumer cast iron or aluminum

Aesthetics of cast-iron radiators is the talk of the town. They require periodic painting, as regulations require that the work surface be smooth and allow dust and dirt to be easily removed.

A dirty coating forms on the rough inner surface of the sections, which reduces the heat transfer of the device. But the technical parameters of cast iron products are on top:

little susceptible to water corrosion, can be used for more than 45 years;
they have a high thermal power per 1 section, therefore they are compact;
they are inert in heat transfer, therefore they smooth out temperature fluctuations in the room well.

Another type of radiators is made of aluminum. Lightweight construction, factory painted, no painting required, easy to maintain.

But there is a drawback that overshadows the advantages - corrosion in the aquatic environment. Of course, the inner surface of the heater is insulated with plastic to avoid contact of aluminum with water. But the film may be damaged, then a chemical reaction will begin with the release of hydrogen, when an excess gas pressure is created, the aluminum device may burst.

The temperature standards of heating radiators are subject to the same rules as batteries: it is not so much the heating of a metal object that is important, but the heating of the air in the room.

In order for the air to warm up well, there must be sufficient heat removal from the working surface of the heating structure. Therefore, it is strongly not recommended to increase the aesthetics of the room with shields in front of the heating device.

The Gigacalorie Path

Megacities sparkle with high-rise buildings. A cloud of renovation hangs over the capital. Outback prays on five-story buildings. Until demolished, the house has a calorie supply system.

The economy class apartment building is heated through a centralized heat supply system. Pipes enter the basement of the building. The supply of heat carrier is regulated by inlet valves, after which water enters the mud collectors, and from there it is distributed through risers, and from them it is supplied to batteries and radiators that heat housing.

The number of gate valves correlates with the number of risers. When performing repair work in a single apartment, it is possible to turn off one vertical, and not the whole house.

The spent liquid partially leaves through the return pipe, and partially is supplied to the hot water supply network.

It is no less important than the return flow of the heating system, what is it

It has the following advantages:

a small number of pipes;
low cost;
ease of installation;
serial connection of radiators does not require the organization of a separate riser for draining liquid.

The disadvantages include the inability to adjust the intensity and heating for a separate radiator, the decrease in the temperature of the coolant as it moves away from the heating boiler. To increase the efficiency of single-pipe wiring, circular pumps are installed. For the organization of individual heating, a two-pipe piping scheme is used.
Hot feed is carried out through one pipe. On the second, the cooled water or antifreeze is returned to the boiler. This scheme makes it possible to connect radiators in parallel, ensuring uniform heating of all devices.
If the installation is done correctly, the liquid is heated in the boiler and begins to rise through the pipes. When heated, the liquid increases in volume, the excess enters the expansion tank. The device of the heating system with an expansion tank Since the heating system is completely filled with liquid, the hot coolant displaces the cold one, which returns to the boiler, where it heats up. Gradually, the temperature of the coolant increases to the required temperature, heating the radiators. The circulation of the liquid can be natural, called gravity, and forced - with the help of a pump. The return is a coolant that, having passed through all the heating devices included in the circuit, gives off its heat and, cooled, enters the boiler again for the next heating. Batteries can be connected in three ways:

1. Bottom connection.
2. Diagonal connection.

Conclusion

We hope that your question has not gone unnoticed. If this is not the case, you may be able to find the answer you need in the video at the end of the article. Warm winters!

In addition, the two-pipe circuit allows you to adjust the heating temperature of each heater separately. The disadvantage is the complexity of installation and the high consumption of materials. Recommended 2 Why is the riser hot and the batteries cold? Sometimes, with hot supply, the return of the heating battery remains cold. There are several main reasons for this:

incorrect installation;
the system or one of the risers of a separate radiator is aired;
insufficient fluid flow;
the cross section of the pipe through which the coolant is supplied has decreased;
the heating circuit is dirty.

Adjustment of the check valve in the heating system Cold return is a serious problem that must be eliminated.