The return in the heating system is a coolant that has passed through all the heating radiators, lost its primary temperature and is already cold and is fed into the boiler for the next heating. The coolant can move both in a two-pipe and in an improved one-pipe heating system.

A single-pipe system implies a sequence of connections for heating radiators. That is, the supply pipe is connected to the first radiator, from which the next pipe goes to the second radiator, and so on.

If a single-pipe heating system is improved, then its design will be something like this: there is one pipe along the perimeter of the entire room, into which you can insert the supply and return pipes of each radiator. In this case, it is possible to install a control valve on each battery, with which you can very successfully regulate the air temperature in a given room.

A big plus of this option is the minimum number of pipes in it. And the minus is the temperature difference between the first radiator from the boiler and the last one. , which will drive all the water through the system and heating much faster, and thus the coolant will not have time to lower the temperature.

The two-pipe version is a wiring of two pipes. One pipe is the supply of hot coolant, the second pipe is the return pipe in the heating system, through which the already cooled water from the radiators enters the boiler. Such a system allows almost parallel connection of all radiators, which makes it possible to flexibly configure each radiator separately without affecting the operation of the others.

Consequences of a cold return

Scheme for heating the return

Sometimes, with an incorrectly designed project, the return flow in the heating system is cold. As practice shows, that the room does not receive enough heat during a cold return, this is still half the trouble. The point is that at different temperature supply and return, condensate may form on the walls of the boiler, which, when interacting with carbon dioxide released during the combustion of fuel, forms acid. She then can disable the boiler much ahead of time.

To avoid this, it is necessary to carefully consider the design of the heating system, special attention must be paid to such a nuance as the return temperature. Or include additional devices in the system, for example, a circulation pump or a boiler, which will compensate for the loss of warm water.

Radiator connection options

Now we can more than confidently say that when designing a heating system, the supply and return must be ideally thought out and configured. With the wrong design you can lose more than 50% percent of the heat .

There are three options for inserting a radiator into a heating system:

1. Diagonal.
2. Lateral.
3. Lower.

The diagonal system gives the highest efficiency and is therefore more practical and efficient.

The diagram shows a diagonal inset

How to regulate the temperature in the heating system?

In order to regulate the temperature of the radiator and reduce the difference between the supply and return temperatures, you can use the temperature controller of the heating system.

When installing this appliance, do not forget about the jumper, which must be in front of the heater. In the absence of it, you will regulate the temperature of the batteries not only in your room, but throughout the riser. It is unlikely that the neighbors will be delighted with such actions.

The simplest and cheap option regulator is the installation of three valves: on the supply, on the return and on the jumper. If you cover the valves on the radiator, the jumper must be open.

There is a huge abundance of different thermostats that can be used in apartment buildings and private homes. Among great variety each consumer can choose for himself a regulator that will suit him according to physical parameters and, of course, the cost.

We hope that the article was useful to you. We will be grateful if you share it in in social networks. The buttons for this are just below. We wish you have a good day, visit us again.

Read also:

Infrared film heating - pros and cons
Safety valve in the heating system

01.02.2016

Why is the bottom of the battery cold and the top hot?

Often on construction forums, people complain about heating systems - the bottom of the battery is cold and the top is hot. It is worth noting that any radiator is warmer at the top than at the bottom, but if the gap between these temperatures is too large, then most likely something is not right with the system. Moreover, this means that the battery gives off less thermal energy than it should. After all, everyone knows that the efficiency of heating devices directly depends on the uniformity of heating of their surfaces.

Today we will try to figure out why this phenomenon occurs and what needs to be done about it.

How to change the battery in the apartment

Earlier we talked about how to quickly and easily replace the heating battery in an apartment with our own hands, in addition to this article, we advise you to read this information

The main reasons for this phenomenon

The problem of the “cold bottom” (let's call it that) is faced not only by those whose system is equipped with fairly old heat exchangers, but also by people who have installed bimetallic heating radiators. There are many reasons for this problem, so it's hard to immediately say why the batteries do not warm up evenly enough. Typically, each case should be considered on an individual basis. So, let's try to deal with the main causes of this malfunction.

Reason #1. Common blockage

The very first (because the most common) cause of this phenomenon is the contamination of heating radiators. Here are the main reasons for the decrease in temperature at the bottom of the device:

1. low-quality coolant is used;
2. air has entered the system.

It is worth noting that in the working fluid there can be not only heat, but also various solid particles. For example, when the heating season begins, and centralized lines are just starting up, the quality of the working fluid is, to put it mildly, disgusting. Things are much better in the case of an individual heating circuit - pollution can only penetrate into it through an open expander.

With this, everything is clear, but how can the presence of air in the system affect the temperature difference? The explanation for this is very unusual - the bacteria are to blame. There is a certain variety of such microorganisms that can only exist in the presence of sufficient oxygen. Such bacteria are known as anaerobic. There is nothing wrong with them, but their metabolic products settle at the bottom of the heating radiator in the form of sediment.

Note! It is also worth noting that the working fluid brings silt into the battery from almost the entire heating line, and it settles there.

Finally, another reason that the bottom of the battery is cold and the top is hot is the special design of the heat exchanger. The liquid in it moves, permanently changing its own motion vector. And inside the heat exchanger there is enough a large number of"secluded places" in which dirt can be deposited.

Video - Cleaning the heating radiator

With this reason, everything is more or less clear, so let's move on to the next one.

Reason number 2. Valve problems

Sometimes the reason that the temperature of the lower part of the radiator is lower than the upper one can be shutoff valves. In previous articles, we have already considered the design features of such reinforcement, so today we will only briefly consider a few highlights. The main purpose of the shut-off valves in the heating circuit is to regulate, as well as to completely / partially block the movement of the working fluid.

Armature can be the following mechanisms.

1. Ball valve.
2. Thermal head, which is equipped with mechanical or electronic control.
3. cone valve.

But where does the decrease in temperature at the bottom of the radiator, you ask? The fact is that as a result of malfunctions with shutoff valves, the circulation of the working fluid inside the heat exchanger is disturbed. After all, the tap can simply become unusable, because of which, even in its open position, the coolant will not be passed. This, for example, can be a failed damper or any other option for the mechanism to fail. It is also worth adding that the correct installation of shutoff valves also plays a very important role in this case.

Note! All taps of this type have an arrow indicating which direction the working fluid should move in order for the heating line to function normally.

And if the valve is installed incorrectly, then one way or another, the movement of the coolant will be disturbed: in this case, it will not matter whether the damper mentioned above is closed or open. We also note that for some types of shut-off valves, requirements are provided regarding the position in which the valve itself should be located relative to space. For this reason, in the event of malfunctions in terms of uniformity of heating of heaters, it is necessary to inspect and stop valves.

Thermostat for heating radiator

Earlier we talked about the types, applications and technical specifications thermostats for a heating radiator, in addition to this article, we advise you to read this information

Reason number 3. Not enough pressure in the system

Low pressure in the line can lead to disturbances in the circulation of the working fluid, as a result of which it may happen that the bottom of the battery is cold and the top is hot. What to do in this case? First you need to make sure that everything is fine with the pressure in the network. As you remember, not so long ago - and we are talking about times Soviet Union- Batteries made of cast iron were widely used. They differed in that they had sufficiently wide passages, therefore, in order for the working fluid to pass through the entire heat exchanger, not so much pressure was required. But modern heating radiators have a slightly different structure.

Quite often, people, even immediately after purchasing such batteries, are faced with a problem when the upper part has a much higher temperature. This is explained by the fact that the outlet and inlet pipes, as well as the labyrinth of the heat exchanger itself, have a small conditional passage. For this reason, in the line, which was originally designed for cast iron, the pressure is simply unable to overcome the resistance and "push" the working fluid through the entire heat exchanger.

In addition, the pressure in the heating main may also drop for other reasons, let's get acquainted with them.

1. Neighbors secretly equipped the apartment with a “warm floor” system that operates on water and is connected to centralized high-temperature heating.
2. There were some problems along the way.
3. The same neighbors equipped their bypass with a crane.
4. Again, the neighbors significantly increased the volume of the heat exchanger by equipping it with several more additional sections.
5. Finally, the same people living in the neighborhood are experimenting in a “black manner” with the regulation of their own heating radiators.

As you can see, often a sudden drop in pressure is associated with some actions of neighbors. As for extended radiators, the volume of the heat exchanger in which exceeds the same indicator from the developer, and the “warm floor” system, it should be noted that all this is contrary to the law. All these manipulations lead to the fact that the pressure in the line decreases, so you should not even be surprised at the fact that the lower part of the batteries in your house will be cold.

Note! Some "experts" visiting specialized forums advise installing shutoff valves on the bypass. After that, it will be possible to adjust the degree of bypass patency by partially closing the valve so that the main flow of the working fluid goes to the radiators. But doing so is strongly discouraged!

The fact is that if the relevant authorities find out about such tricks, they will force them to pay a fine and do everything as it was. By the way, if the bypass is located at a sufficiently large distance from the radiator, then the movement of the coolant in the latter can also be disrupted. And the situation will only get worse if the bypass diameter is the same as the diameter of the supply pipeline. Because of this, it can also happen that the bottom of the battery is cold and the top is hot.

Video - Bleeding in case of cold radiators

Reason number 4. Installation done wrong

Another common situation, which is the wrong connection of the battery. Simply put, by mistake or for some other reason, the wrong device connection diagram was used.

Reason number 5. The coolant is moving at insufficient speed

This kind of situation is explained quite simply. If the heated liquid high speed flows through metal pipe, then as a result the pipe will be hot in all places. But if the speed of movement of the liquid is insignificant, then during the circulation along the main line it will be cooled, and the temperature of the end of the pipe will be noticeably lower. The same applies to the radiator, if the bottom is colder than the top.

1. It is also worth noting that there are two main reasons for the low circulation rate of the coolant.
2. Too narrow a section of the pipeline in a particular place.
3. If the working fluid, in principle, moves slowly along the line.

In turn, the reason for the insignificant circulation rate (if we do not take into account the narrowed section) is probably that the circulation pump has stopped working or has insufficient power for this. Moreover, this happens if there is no circulation pump at all, that is, there is a heating main with the circulation of a working fluid of a natural (gravitational) type. Or, alternatively, if the pipeline is already narrowed elsewhere.

It remains to be seen why the pipe can narrow. There are several possible reasons for this.

Quite often in residential apartment buildings during heating season you may encounter the following problem: the riser is hot, and the batteries are cold. This applies to both new buildings and old houses. Residents in most cases do not know how to deal with such a situation. That is why their attempts to repair heating system alone do not lead to the desired result. In this matter, you definitely need help or advice from a specialist. After all, only a person with the necessary knowledge and experience can solve the problem of why the pipes are hot and the batteries are cold.

Why the batteries are cold and the riser is hot, experts explain

On cold batteries, do not warm your hands.

There can be a lot of reasons why the coolant supply pipe is hot and the radiator is cold. Specialists for general development only mention the main ones:

• the central tap on the heat supply line is closed or the return line is closed;
• insufficient coolant flow;
• airing the system or a specific riser, radiator;
• the heating system is not balanced;
• pollution in the heating circuit;
• reduction in the cross section of the heat carrier supply pipe.

If the riser is warm in the apartment, and the battery is cold, you must contact the organization responsible for the heat supply of the house. Its specialists are obliged to eliminate any malfunction free of charge and within 24 hours.

However, the following actions of the residents of the house will help the masters who came to the call to fix the problem as soon as possible. heating circuit:

• it is necessary to install a hot pipe, and the radiator is cold in only one apartment, or this problem affects the entire riser. Perhaps the heating wiring of the entire entrance is faulty;
• does not interfere with going around all the entrances and seeing if the heating elements are hot there;
• you can go down to the basement and inspect the pipes for breakdown. Even a drip leak leads to a fall . This adversely affects her work.

Circuit cleaner.

If the batteries do not heat up the riser . If the riser is cold, the battery is cold - this is a sure sign that the main line through which the coolant flows is blocked. In confirmation of this, you need to walk through the neighboring apartments. They should warm up well. In this case, only a plumber can fix the breakdown, who will have drawings of the house heating wiring in his hands.

The next state of affairs, when the pipe is hot and the battery is cold, indicates a blockage in the system or the presence of an air lock. It prevents the penetration of the coolant into the heating element. From this, the latter does not warm up. Blockages are eliminated only if the radiator is completely disassembled and air under pressure is driven through it. This is only possible for a specialist who has necessary tools and technology.

If the radiators in the entire entrance do not heat . When the radiator is cold and the riser is hot, you need to pay attention to the pressure in the circuit. With insufficient pressure, the coolant cannot pass through all the radiators in the circuit. As a result, the batteries lower their temperature as they move away from the heat-carrying main. Residents of the house cannot afford to increase the pressure in the system on their own, and therefore it is recommended to seek help from professionals. More specifically, call the organization that is responsible for the heat supply of the building.

Supply and return can be interchanged.

Residents of a new house, when the heating system is first started, can observe the following situation when the battery is cold and the return is hot. Here it is appropriate to assume that errors were made during installation. heating elements. In this case, the pipes supplying the coolant and the return flow of the circuit are reversed. If we are talking about an individual heating circuit, then you should take a closer look at the circulation pump. It may not have been installed correctly.

When asked why there is a cold return in batteries, experts unequivocally point to an improperly designed heating system. In some cases, it is appropriate to talk about a small coolant flow rate.

What to do if the batteries in the apartment are cold and the riser is hot?

Regardless of whether cold heating equipment is only in the riser or in the whole entrance, and possibly completely in the house, you need to seek help from qualified specialists. In case of apartment building is a plumber for a company that is responsible for heating the house.

Cold batteries with a hot riser may be due to clogging of the system or the formation of an air lock in it. An important factor is the pressure in the wiring. In some cases, the problem of low coolant flow is relevant. It is possible to independently find out the reason for the low efficiency of the heating elements. But only a true professional in his field will unequivocally answer the questions that have arisen and competently eliminate the breakdown. How to make heating radiators better to heat will help the video:

The boiler is working, but the batteries are not heating: why is there a cold return in the heating system? Why is there a cold return in the heating system

causes of problems with batteries in the apartment

The heating system is complex structure, consisting of several elements combined into one circuit and put into operation by means of chain reaction.

But it happens that the system fails and the water in the batteries becomes cold. The reason for this may be problems with the return.

What is a return flow in a heating system?

The return is a coolant located inside the heating system. During operation, it passes through all heating devices and gives them heat. Then, already cooled, the coolant returns to the boiler, where it is heated and begins a new cycle.

Photo 1. Heating scheme with a circulation pump and expansion tank. The arrows show the movement of the coolant.

Both ordinary water and antifreeze act as a coolant. It is put into operation either naturally (under the influence of gravity) or forcibly (with the help of a pump).

Causes of return problems in batteries of a private or apartment building

There are several reasons why the return line is not warm enough or even cold at all. Common problems are:

• insufficient water pressure in the system;
• a small section of the pipe through which the coolant passes;
• incorrect installation;
• air pollution or contamination of the system.

If a problem with a cold return arose in an apartment, then the first thing to do is

Ogon.guru

where they pass, the temperature difference between them, the pressure on the radiators

The comfort of the family will depend on how efficiently the heating system in the house is set up. winter period. If the batteries do not heat up well, it is necessary to fix the malfunction, and for this it is important to know how the heating works in general.

Water space heating is a source of heat and a coolant that is distributed through the batteries. Supply and return is present in one- and two-pipe systems. In the second, there is no clear distribution, it is conventionally customary to divide the pipe in half.

Features of supply in the heating system

The heat supply comes immediately from the boiler, while the liquid is carried through the batteries from the main element - the boiler (or the central system). It is typical for single pipe system. If it is improved, then it is possible to insert pipes also on the return line.

Photo 1. Heating scheme for a private two-story house including supply and return pipes.

Where is the return

In short, the heating circuit consists of several important elements: heating boiler, batteries and expansion tank. In order for heat to flow through the radiators, a coolant is needed: water or antifreeze. With proper construction of the circuit, the coolant is heated in the boiler, rises through the pipes, increasing its volume, and all the excess enters the expansion tank.

Based on the fact that the batteries are filled with liquid, hot water displaces cold water, which, in turn, enters the boiler again for subsequent

ogon.guru

Heating system repair - construction

Heating system repair

This article lists the main malfunctions that can happen to the heating system of a private house, as well as ways to fix them. Troubleshooting the heating system can be divided into two types. Repair of the heating system with your own hands can be done in terms of the wiring of the heating system: radiators and fittings. All problems that occur in the boiler room and equipment require special knowledge and experience, so the repair of the heating system. related to equipment, it is better to entrust specialists.

Those questions that the owner of the house can solve himself are listed below.

Attention! If the heating system is started up for the first time after installation or for the first time after a long period of inactivity, it must be allowed to level off. This can take from a couple of days to several weeks. The system will need this time in order to heat the house and completely get rid of the air, until this is done, there is no need to talk about normal operation. At this time, you need to bleed air from the radiators from time to time and feed the system if necessary.

If the heating system has leveled off and problems remain, then you can begin to find out the causes and eliminate them.

Problems that you can fix yourself:

Battery does not heat up

If one or more radiators do not heat or heat poorly, then the first step is to check if there is air in them using air vents. If from descenders water is coming, and the radiator still does not heat, then you need to make sure that both taps of this radiator are open (such inattention can often occur). The next step is to check if the radiator is clogged. To do this, other heating radiators that heat and are on the same branch as the idle one must be shut off so that all the water goes through this radiator. If he began to warm, then he is not clogged. In this case, it is necessary to carry out hydraulic alignment of the branch. in plain language, it is necessary to cover the remaining radiators on the branch, so that the non-working one gets more. You need to be prepared that the alignment will take more than one day, because the heating system may be slow to respond to changes in settings. If the valves in front of the radiator are fully open and it is cold, then it is clogged (extremely low probability). Basically, the last radiators on the branch may not heat up. But this can always be eliminated by hydraulic leveling. If someone tells you that "it does not pump there" or "insufficient pump power", do not rush to believe and touch the pump or pipes. In order for the pump to "not pump" it is necessary to "try hard" during the installation of the heating system. If one or more of the last radiators do not heat up even after working with taps, then there may be an air lock in the pipes (see violation of circulation in the heating system).

Pressure drops in the heating system

Once again, we focus on the fact that the heating system after launch should work for several days or even weeks. Air is dissolved in the system, it gradually comes out on automatic air vents and with manual deaeration of radiators. This results in a loss of pressure. At first, frequent replenishment of the heating system is normal. If the system has been running for more than a month, and the pressure drops, then you can check this version. If the volume of the expansion tank is incorrectly calculated, pressure surges in the heating system are possible, as a result of which the safety valve may operate and discharge water, as a result of cooling - a pressure drop. If everything is in order with this, then there is a leak in the system, which is not pleasant, you need to look for a leak.

Pressure drops in the heating system

The expansion tank is responsible for compensating for changes in the volume of the heating system. Therefore, if the pressure changes over a wide range with a change in temperature, then the reason is in the expansion tank: either it is broken, or there is an incorrect calculation of the volume of the expansion tank. This may lead to operation safety valve or stop the boiler due to insufficient pressure. see pressure, volume of the heating system and selection of an expansion tank.

Return is hot, supply is cold

Why is the return flow hot and the supply cold? This is a rare occurrence. It can be observed when the pump is installed in reverse and without check valve. This is also possible due to the operation of the floor heating pump. When the floor is just started and heats up the structure, it works at full capacity and can, under certain circumstances, change the circulation in the radiator circuit. As the floor warms up, this may self-correct. If the pipes are hidden, then you need to check if the pipes are mixed up (supply with return). You can do it in different ways: with water or just blow.

No circulation or poor circulation in the heating system

The boiler is working, the pump is definitely working, but there is no circulation in the heating system. Again, the first thing we do is check the air in the radiators. Then, we check the valves (taps), which can be closed somewhere by inattention. The next step is to clean the filter in front of the boiler and in other places, if any. This will solve the issue in 90% of cases, even if the heating system has recently been installed. If not, then we check the heating pipes for the possibility of air locks in the pipes (see installation of the heating system). If there are such sections in the heating distribution, then you can temporarily solve the problem by draining water from the radiator under pressure. which is behind the loop, the flow of water will expel the air from the loop. If possible, an automatic air vent should be installed on large hinges. This will eliminate the problem in the future. If, as a result of the above measures, circulation is not restored, then you need to contact a specialist.

Based on site materials: http://teplo-info.com

fix-builder.com

ways to remove air locks, removing an air lock from a radiator, removing air from the system, causes of air locks, determining the location of an air lock, the procedure for starting a heating system

Air locks common cause violations of the heating system. They may appear on systems central heating and individual. Cold risers or heating radiators, noise in pipes are all caused by air in the heating system. The reasons for the appearance and how to remove air from the heating system will be discussed in this material.

Reasons for airing the system

Air in the heating system is a fairly common occurrence at the beginning of the heating season. Even in a well-designed and properly installed system, air pockets can occur. There can be several reasons for the appearance of air in the heating system.

• When repairing the heating system, it is necessary to drain the water, which they do. At this point, the system is filled with air. At the end of the repair, the systems are filled again, but the air remains in it.
• When replacing heating appliances, as well as during repairs, part of the water is drained. This allows air to enter the system.
• After repairing or replacing radiators, it is necessary to start the heating system correctly and remove all air. This work is lengthy. Often in a hurry and break the technology. After starting, due to the remaining air, the operation of the heating system is disrupted.
• Often the cause of air is aluminum radiators. This type of radiator is prone to gas formation. The gases formed during the corrosion of the radiator create an air lock.
• Corrosion of pipes of the heating system is an inevitable process. During corrosion, various gases are released into the coolant, which can cause air locks.
• Cold water contains a large amount of air, which, when heated, is released and forms air pockets.
• The reason for airing the heating system may be improperly functioning automatic air vent valves. Contaminated coolant can cause clogging of valves. As a result, their work will be disrupted and air will not be able to leave the system.

Determination of places of formation of an air lock

An important part of removing air from the system is the correct determination of the location of the formation of an air lock. Depending on the location of the air, apply different ways its removal.

In a heating system of any type, air locks can form in two places: in pipes and radiators. In pipes, an air lock is formed, as a rule, in the extreme risers, in which the difference in supply and return pressure is minimal. Radiators collect air in upper corner located opposite the supply connection.

The first thing to start with is to make sure that all taps on the risers and heating radiators are open.

If there is a jumper (bypass) on the riser next to the heating radiator connecting the supply and return lines bypassing the radiator, then we first check it. If it is hot and the radiator is cold, then there is an airlock in the radiator. If it's cold, it means that the entire riser is not working.

Fig.1.

If there is no jumper, then we compare the supply and return temperatures. If both pipes have the same temperature, then the problem may be in both the riser and the radiator. In this case, we first try to bleed the air from the radiator. If the supply is warmer than the return, then there is an air lock in the radiator. Because of it, the entire riser does not work.

Removing an air lock from a heating radiator

Heating radiators are more prone to airing than other elements of the system. In most cases, it is enough to bleed the air from the radiator, and the heating system starts to function properly.

There are two ways to remove air from the radiator:

• through an air vent or valve;
• restart the heating system.

If the heating radiator is equipped with a valve (Mayevsky tap), then you can remove air from the radiator with your own hands. All modern radiators are equipped with an air vent or valve. The air vent is installed on the upper radiator cap on the opposite side of the supply pipe.

Fig.2. Mayevsky crane on a heating radiator.

To bleed the air, you need a special key, sold with the valve, to open the nipple. If there was air in the radiator, you will hear a hiss. Before opening the valve, place a container under it to receive water. There won't be much water, so it will be enough liter jar.

As the hissing ends, this indicates that the air has escaped. Next, you should wait for the appearance of water from the nipple. As soon as the water pressure from the nipple becomes constant, it can be closed. There is no more air in the radiator.

If there is no air vent, then the heating system must be restarted. In the case of an urban central heating system, restarting it yourself is difficult and specialists should be called. You can restart the individual heating system with your own hands.

Starting / restarting the heating system

Starting the heating system is a simple, but long and responsible process. Its main task is to fill the system and simultaneously remove all air from it. The order of starting the system is as follows.

Start with preparatory work. Every heating system has an air vent. Manual or automatic. It is located at the highest point of the system, and should be in good condition. In the case of a manual air vent, it is open.

Next, close the supply pipe. The system is filled through the return line. Under the action of water, the air tends to rise to the highest point of the system, where the air vent is located. If you do not rush, then all the air will come out the first time.

If we are talking about restarting the system, then they do exactly the same. Shut off the supply, open the air vent and open the return. Water, rising up through the pipes, squeezes air out of the system through the air vent. You can determine whether there is air left or all of it has come out by the uniformity of the pressure of water from the air vent. If the pressure is uniform, then the air is removed. The air vent can be closed and the system turned on for circulation.

Typically, a manual air vent is a faucet. Water will also flow out through this faucet along with air. For an urban central heating system, the loss of several hundred liters of water is not a problem. For a private house where antifreeze is used instead of water, this is unacceptable. Therefore, in individual system Heating systems are equipped with automatic air vents. They allow air to pass through, but not antifreeze.

Fig.3. Automatic air vent for heating system.

How to prevent airing the system?

As mentioned earlier, airing the system is inevitable. The only way to prevent air from entering the system is to properly start it up. However, the remaining factors described at the beginning of the article are enough for air jams to appear in the system. Therefore, it is more expedient to give some advice on how to facilitate the elimination of air congestion.

An air vent must be provided on each heating radiator. The same applies to water warm floors.

On each riser, it is necessary to provide taps to disconnect it from the system.

At the very top and bottom of the riser, taps with taps should be installed. This will allow you to drain the riser or release air from it without disturbing the operation of the entire system.

It is necessary to choose pipes and heating radiators that are not prone to gas formation. Gas appears as a result of metal corrosion processes. If there is no corrosion, then gas formation will be minimized, and, consequently, airing.

mhremont.ru

Heating return temperature | Thermal Power Engineer Blog

Good day, dear readers! If you have at least a little experience with the operation and maintenance of central heating systems, then you have probably heard about such a thing as return overheating. What is it, why does it occur, and how to deal with it?

Return overheating is when the temperature of the water leaving the house exceeds the temperature that should be on the temperature chart. That is, according to the schedule, let's say that in the return line it should be 63 ° C, in fact 67 ° C. Moreover, overheating according to the temperature graph should not be looked at by the outside temperature, since heating network inertial, and the temperature changes during the day. You need to compare by temperature t1, that is, the temperature in the supply.

We first look at the thermometer readings for the supply t1, then in the temperature graph, what should be the corresponding temperature t2. Then we look at the actual t2 on the thermometer and compare it with t2 according to the schedule. It is good when t2 coincides with or slightly less than t2 according to the temperature graph. And it’s bad if, in fact, the return temperature is too high against the schedule. According to clause 9.2.1 of the Rules technical operation thermal power plants" " average daily temperature return network water should not exceed the specified temperature chart temperature by more than 5%.

Now cunning power engineers include without fail this clause from the Rules in heat supply contracts. That is, if your overheating jumps out beyond 5%, then you will additionally be charged a fine for exceeding the return flow. If the overheating is within these 5%, there will be no penalty, but it is better for you to eliminate the overheating anyway. The ideal option is when you have a return line in your schedule, or a little lower.

There are basically two reasons for overheating. The first is the flow through various jumpers between the supply and return, that is, from the supply to the return. Basically, this happens either through the hot water line or through ventilation. Therefore, if you have overheating, first of all, see if there is a flow from the supply to the return. But in fact, this rarely happens.

The main and main reason for overheating, in 95% of cases, is the increased consumption of network water. That is, during overheating, network water passes through your heating unit more than you actually need. Why are power engineers so struggling with overheating? Increased consumption of network water indicates a lack of estimated consumption coolant, that is, the flow rate is overestimated and more than the calculated one. And this is an overestimated circulation, in which there is an increase in the consumption of electricity to drive the network pumps at the heat source. Electricity costs money, so an overestimated return is a direct loss for the heat supply organization.

I had to hear the opinion that an overestimated return is beneficial to the consumer. Say, if you return T2 from the house with overheating from the schedule, then heat consumption will become less, because. the difference between T1-T2 will decrease. However, it is not. The amount of heat Qcons., Gcal, is considered in the general case as follows. The amount of heat supply Q 1 = G1 * (t1- th.v.) * 0.001 where G1 is the water consumption in tons per hour; t/h; t1 – supply water temperature; th.v. - the temperature of cold water, which is prepared and heated at the heat source, usually tx.w. 5 °С is accepted.

The amount of heat on the return is considered similarly: Q 1 \u003d G2 * (t2- th.v.) * 0.001. The consumed heat consumption is determined by the formula: Qcons = Q1- Q2= G1*(t1- tx.a.)*0.001- G2*(t2- tx.a.)*0.001. So it turns out that although the difference t1-t2 decreases in case of overheating, the increased consumption G outweighs the formula in the end, and the amount of heat Qcons still turns out to be greater. In general, the conclusion is this: for the consumer, overheating on the return line means overheating the entire building and an increase in the amount of heat consumed, and it is unambiguously economically unprofitable for the consumer.

How to eliminate overheating? To do this, in the ITP (heating unit) at the supply, before the elevator, it is necessary to adjust the pressure regulator (or flow regulator), depending on what is installed. What is an RD pressure regulator, I wrote here. By adjusting the pressure through the RD, and looking at the indication of the heat meter, or thermometers and pressure gauges, you can set required pressure, at which the flow rate will not exceed the calculated one. Better of course, let the experts do it. If the heating unit is automated by modern automation, then during the normal operation of the equipment, overheating is impossible in principle.

More recently, I wrote and published a book entirely devoted to the heating return, return overheating. It is called "Everything you wanted to know about overheating the return!".

1. Introduction

2. What is a heating return?

3. Why does the return flow overheat?

4. Penalties from the heat supply organization for overheating the return.

5. How to regulate the heating system and eliminate overheating in the return pipeline?

6. Conclusion

Everything you wanted to know about overheating the return!

I will be glad to comments on the article.

teplosniks.ru

The heating system is complex structure, consisting of several elements combined in one circuit and is put into operation by means of a chain reaction.

But it happens that the system crashes and the water in the batteries becomes cold. The reason for this may be problems with the return.

What is a return flow in a heating system?

The return line is coolant located inside the heating system. During his work, he passes through all heating devices and gives them warmth. Then, already cooled, the coolant returns to the cauldron, where it is heated and starts a new cycle.

Photo 1. Heating scheme with a circulation pump and an expansion tank. The arrows show the movement of the coolant.

Acts as a heat carrier as a conventional water, and antifreeze. It starts up either naturally(under the influence of gravity), or forcibly(using a pump).

Causes of return problems in batteries of a private or apartment building

There are several reasons why the return line is not warm enough or even cold at all. Common problems are:

• insufficient pressure water in the system;
• small pipe section through which the coolant passes;
• incorrect installation;
• air pollution or pollution systems.

If a problem with a cold return has arisen in an apartment, then the first thing you should pay attention to is pressure. This is especially true for premises. on the upper floors. The fact is that the principle of the return is to quickly and continuous flow of liquid by system. And if her speed drops, then the coolant will not have time to push out cold water and the batteries don't get hot.

Another reason for the failure of the return flow is pollution of the heating circuit. Usually, major cleaning systems in high-rise buildings not done often. Sediment, which accumulates over time on the walls of the pipes, prevents the passage of fluid.

main reason interruptions in the operation of the heating system in a private house - incorrect installation. Most often this happens when the installation is carried out without the participation of specialists. Being incompetent in this matter, it is quite easy to mix up the supply and return pipes, or choose pipes of the wrong size.

Both in an apartment and in a private house, the problem of a malfunction of the heating system can be associated with insufficient speed water supply or airiness. In a similar way, the work of the return is affected by the contamination of the pipes.

Troubleshooting methods. Why is cleaning necessary?

To understand exactly how to solve the problem, you first need to set its source. If the batteries become cold due to insufficiently fast water circulation, in this case the installation of a special pump. It will regularly push water into the circuit under a certain pressure, thereby not allowing the system to stop or slow down.

Photo 2. Marking circulation pump Grundfos allows you to choose the most suitable one and install it correctly.

If the cause is clogged pipes, then they just need to clean up. You can do this in several ways:

• using water-pulsing mixture;
• with help biological products;
• through pneumohydraulic shock.

Important! Such a cleaning regularly to prevent new problems from appearing.

In the event of a malfunction due to improper installation of the equipment, contact the master. A qualified specialist will certainly understand the problem and fix all the problems. In addition, he will give good advice and recommendations care and maintenance of the system.

Useful video

Check out the video for one of the possible problems with return line - battery pollution.

What problems arise in the apartment due to the cold return

Violation in the work of the return line entails certain problems and troubles.

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