Heating battery return is cold - device, causes, solutions

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

Regardless of whether the cold heating equipment is only in the riser or in the entire entrance, and possibly throughout the house, you must seek help from qualified specialists.
In the case of an apartment building, this is a plumber of the company that is responsible for the heating supply of the house. Cold batteries with a hot riser may be due to a clogged 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 heating elements. But only a true professional in his field will clearly answer any questions that arise and competently fix the breakdown. This video will help you to make your radiators heat better:

Often, residents of both apartment buildings and private houses are faced with the problem of cold radiators. In this article we will explain why this problem occurs and what to do if the batteries are cold.

Manual adjustment of TP collectors

The simplest, although time-consuming, setting method is to adjust the temperature of the heated floor using manual valves. The task is somewhat simplified by installing flow meters (rotameters) on the comb.

Flow meters simplify the dosage of the amount of circulating coolant (flow) in one separate circuit of the underfloor heating system. In the case of group temperature control throughout the collector, the rotameter can also be used to balance the flow of coolant (smoothing out the difference in hydraulic resistance) along loops of different lengths.

The main elements of a flow meter valve are:

Manual adjustment of the underfloor heating manifold is carried out by screwing/unscrewing manual valves or adjusting the throughput of flow meters.

Important! Improvement in the efficiency of the underfloor heating system, as a result of its manual adjustment, will be noticeable only in the case of intensive circulation of the coolant through it. This can only be achieved by using a separate heat pump.

The sequence of manually setting the temperature of a warm water floor

At the beginning of the adjustment operations, it is necessary to make sure that the pipelines of the TP system (secondary circuit) are completely filled with coolant and have no air pockets. They are filled following the main heating system (primary circuit). At this time, all shut-off and control valves on the collectors must be closed.

After opening the main valves for the supply and return of the distributors for heated floors, the shut-off devices on each of the loops are opened sequentially. Air is bled through Mayevsky valves or automatic comb air vents. It is recommended to fill the next branch only after the previous one has been completely filled and its air has been guaranteed.

Having completed filling the first loop, it is necessary to turn on the heat pump of the secondary heating circuit and circulate the coolant through its system. The efficiency of liquid circulation is checked with built-in or overhead thermometers. As a last resort, you can simply put your hands on the supply and return pipes at the same time - they should be warm, but with a slight difference in heating.

The filled first loop should be cut off from the collectors at both ends using local shut-off and control valves. Then, the above actions are carried out with the next loop.

After sequential filling of all heat pump circuits, their shut-off devices are opened and the heat pump is switched on to operating mode. The temperature of the warm water floor is adjusted through the supply of coolant to each of its branches. It is set by changing the liquid flow rate (with a valve or rotameter), and control is carried out by changing the temperature gradient between the supply and return flow. Ultimately, this difference for different circuits should be the same, within 5-150C. The longer the loop, the more intense the coolant will cool and the greater its consumption required.

Important! Heat exchange in underfloor water heating systems occurs with great inertia. The delay in heating the coating surface is especially noticeable if the pipes are laid in too thick a concrete pour (over 60-70 mm). Sometimes the effect of changing the coolant supply intensity becomes noticeable only after a few hours.

To monitor the correct adjustment of a warm water floor, it is rational to use non-contact laser or contact electric thermometers. Their installation to measure the temperature of the supply and return pipes will help reduce the time to obtain the result of changing settings from several hours to 10-15 minutes.

How to protect the pump from malfunction

It is advisable to always maintain the required volume of coolant water in the pipes. Otherwise, the pump will wear out, both in case of excess water volume and in case of insufficient water volume.

To be on the safe side and avoid breakdowns of fairly expensive pumping equipment, it is recommended to adhere to some basic rules for operating equipment of this type:

• Do not allow the pump to turn on without coolant in the closed circuit. That is, if there is no water in the heating system pipes, then you should not “torture” the pump. This will cause your equipment to break down quickly.
• It is advisable to always maintain the required volume of coolant water in the pipes. Otherwise, the pump will wear out, both in case of excess water volume and in case of insufficient water volume. For example, if a pump can distill an amount of water from 5 to 105 liters, then the need to work with volumes from 3 to 103 liters will greatly wear out the working components of the unit, which will lead to its failure.
• In case of prolonged downtime of the pump (during the low heating season), it is necessary to run the unit in the operating position for at least 15 minutes once a month. This will avoid oxidation of all movable elements of the pump unit.
• Try not to exceed the coolant temperature above 65 degrees Celsius. A higher rate will negatively affect the working and movable parts of the structure.
• In this case, check the pump housing for leaks more often. If there is even the slightest leak somewhere, you should immediately identify the malfunction and carry out maintenance on the pump.

Boiler protection from cold return

Having allocated a considerable amount of funds to create a water heated floor (WF) system, the user sometimes does not receive the expected level of comfort or savings, which supporters of such heating vying with each other about. And if the calculation of communications was carried out correctly, and the installation was carried out without errors, then, most likely, the reason for the ineffectiveness of the thermal installation is in its incorrect functional settings. These primarily include adjusting the temperature of the warm water floor. At the same time, it is based on the concepts of the temperature of the coolant in the system and the surface of the floor covering, as well as the temperature regime in the rooms.

Let's look at how these concepts are linked together in practice, with different methods of TP management.

How to make radiators hot - looking for solutions

If you find that the return is too cold, you should take a number of steps to find the causes and troubleshoot problems. First of all, you need to check that the connection is correct. If the connection is not made correctly, the down pipe will be hot when it should be slightly warm. The pipes should be connected according to the diagram.

To avoid air pockets that impede the flow of coolant, it is necessary to provide for the installation of a Mayevsky valve or bleeder for air removal. Before bleeding the air, you need to turn off the supply, open the tap and let out the air. Then the tap is turned off and the heating valves open.

Often the cause of cold return is the control valve: the cross-section is narrowed. In this case, the tap 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. You need to check them for passability, remove dirt and deposits, and clean them well. If passability cannot be restored, the clogged areas should be replaced with new ones.

If the coolant flow rate is insufficient, you need to check whether there is a circulation pump and whether it meets the power requirements. If it is missing, it is advisable to install it, and if there is a lack of power, replace or upgrade it.

Knowing the reasons why heating may not work efficiently, you can independently identify and eliminate malfunctions. Comfort in the house during the cold season depends on the quality of heating. If you carry out the installation work yourself, you can save on hiring third-party labor.

Economical energy consumption in the heating system can be achieved if certain requirements are met. One option is to have a temperature diagram, which reflects the ratio of the temperature emanating from the heating source to the external environment. The values ​​of the values ​​make it possible to optimally distribute heat and hot water to the consumer.

High-rise buildings are mainly connected to central heating. The sources that transmit thermal energy are boiler houses or thermal power plants. Water is used as a coolant. It is heated to a given temperature.

Having gone through a full cycle through the system, the coolant, already cooled, returns to the source and reheats. Sources are connected to consumers by heating networks. Since the environment changes temperature, thermal energy should be adjusted so that the consumer receives the required volume.

Heat regulation from the central system can be done in two ways:

1. Quantitative.
   In this form, the water flow changes, but its temperature remains constant.
2. Qualitative.
   The temperature of the liquid changes, but its flow does not change.

In our systems, the second regulation option is used, that is, qualitative. Here there is a direct relationship between two temperatures:

coolant and environment. And the calculation is carried out in such a way as to ensure the heat in the room is 18 degrees and above.

Hence, we can say that the temperature graph of the source is a broken curve. The change in its directions depends on temperature differences (coolant and outside air).

The dependency schedule may vary.

A specific diagram has a dependency on:

1. Technical and economic indicators.
2. CHP or boiler room equipment.
3. Climate.

High coolant values ​​provide the consumer with great thermal energy.

Below is an example of a diagram, where T1 is the coolant temperature, Tnv is the outside air:

A diagram of the returned coolant is also used. A boiler house or thermal power plant can estimate the efficiency of the source using this scheme. It is considered high when the returned liquid arrives chilled.

The stability of the scheme depends on the design values ​​of fluid flow of high-rise buildings.

If the flow through the heating circuit increases, the water will return uncooled, as the flow rate will increase. Conversely, with minimal flow, the return water will be sufficiently cooled.

The supplier's interest, of course, is in the supply of return water in a cooled state. But there are certain limits for reducing consumption, since a decrease leads to loss of heat. The consumer’s internal temperature in the apartment will begin to drop, which will lead to violation of building codes and discomfort for ordinary people.

Radiator connection diagrams

How well the radiators will heat depends on how the coolant is supplied to them. There are more and less effective options.

Radiators with bottom connection

All heating radiators have two types of connection - side and bottom. There can be no discrepancies with the bottom connection. There are only two pipes - inlet and outlet. Accordingly, coolant is supplied to the radiator on one side and removed from the other.

Bottom connection of heating radiators for single-pipe and two-pipe heating systems

Specifically, where to connect the supply and where the return is connected is written in the installation instructions, which must be available.

Heating radiators with side connection

With a lateral connection, there are many more options: here the supply and return pipelines can be connected into two pipes, respectively, there are four options.

Option #1. Diagonal connection

This connection of heating radiators is considered the most effective, it is taken as a standard and this is how manufacturers test their heating devices and the data in the thermal power passport for such a connection. All other connection types transfer heat less efficiently.

Diagonal diagram for connecting heating radiators with a two-pipe and one-pipe system

This is because when the batteries are connected diagonally, the hot coolant is supplied to the upper inlet on one side, passes through the entire radiator and exits from the opposite, lower side.

Option #2. Unilateral

As the name implies, pipelines are connected on one side - supply from above, return from below. This option is convenient when the riser runs on the side of the heating device, which often happens in apartments, because this type of connection usually predominates. When the coolant is supplied from below, this scheme is used infrequently - it is not very convenient to position the pipes.

Lateral connection for two-pipe and one-pipe systems

With this connection of radiators, the heating efficiency is only slightly lower - by 2%. But this is only if there are few sections in the radiators - no more than 10. With a longer battery, its farthest edge will not heat up well or will remain cold at all. In panel radiators, to solve the problem, flow extenders are installed - tubes that bring the coolant a little further than the middle. The same devices can be installed in aluminum or bimetallic radiators, thereby improving heat transfer.

Option #3. Bottom or saddle connection

Of all the options, saddle connections for heating radiators are the least effective. Losses are approximately 12-14%. But this option is the most inconspicuous - pipes are usually laid on the floor or under it, and this method is the most optimal from an aesthetic point of view. And so that losses do not affect the temperature in the room, you can take a radiator a little more powerful than required.

Saddle connection of heating radiators

In systems with natural circulation, this type of connection should not be made, but if there is a pump, it works well. In some cases, it’s not even worse than the side one. It’s just that at a certain speed of movement of the coolant, vortex flows arise, the entire surface heats up, and heat transfer increases. These phenomena have not yet been fully studied, therefore it is not yet possible to predict the behavior of the coolant.

The comfort of the family in winter will depend on how efficiently the heating system in the house operates.

If the batteries heat up poorly, it is necessary to eliminate the malfunction, and for this it is important to know how heating works in general

Water heating of a space is a heat source and coolant that is distributed through the radiators. Supply and return are present in one- and two-pipe systems. In the second, there is no clear distribution; the pipe is conventionally divided in half.

Basic malfunctions of heating systems and their elimination

Air jams

Air pockets occur in radiators and pipes and interfere with the normal circulation of water in the heating system. They appear for various reasons:

• violation of the technology for filling the system with water after the summer period;
• non-compliance with water deaeration regime;
• performing repairs with disassembling pipelines;
• failure to observe slopes when installing the heating system;
• air leakage through leaky joints.

To remove air from the system, use a Mayevsky valve installed on the radiator. You should open it, wait until the air comes out, the hissing stops, and the water begins to pour out calmly without bubbles. After this, the valve is closed. Don't forget to provide a container or towel to drain the water.

Old cast iron batteries do not have Mayevsky taps. The air is released without completely unscrewing the plugs at the ends of the radiators. It is better to entrust this operation to plumbers - if you unscrew the plug completely, you can flood the apartment.

The heating system is a complex structure consisting of several elements combined into one circuit and put into operation through a 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 line.

Elimination

If you notice that the bottom is significantly colder than the top, then urgent action is required. It is necessary to follow the following algorithm to find the cause:

1. Checking the correct connection.
2. Inspect the radiator, bleed and clean it.
3. Assess the condition of the control valves.
4. Check the pipes.
5. Determine the type of heating system, install or replace the circulation pump.

The first step is to check the correct connection. To do this, it is necessary to estimate the temperature of the lower pipe. If the return and supply were connected incorrectly, it will be hot. You will need to reconnect and build the circuit correctly. When connected correctly, this element remains slightly warm.

Stabilization of pressure in the heating system

Expansion of water as a result of heating is a natural process. In this indicator, the pressure may exceed a critical value, which is unacceptable from the point of view of heating operation. In order to stabilize and reduce pressure on the internal surfaces of pipes and radiators, it is necessary to install several heating elements. Adjusting the heating system in a private home will be much easier and more efficient with their help.

Adjusting the expansion tank

Expansion membrane tank

It is a steel container divided into two chambers. One of them is filled with water from the system, and air is pumped into the second. The air pressure value is equal to normal in heating pipes. If this parameter is exceeded, the elastic membrane increases the volume of the water chamber, thereby compensating for the thermal expansion of water.

Before adjusting the pressure drop in the heating system, you need to check the condition and settings of the expansion tank. You can adjust the pressure in the heating system by purchasing a tank model with the ability to change it in the air chamber. As an additional measure, install a pressure gauge to visually monitor this value.

However, if there is a significant surge in pressure, this measure will not be enough. This way you can adjust the pressure drop in the heating system if it does not exceed a critical value. Therefore, it is recommended to install additional devices.

How to adjust a security group

Heating safety group

This group of devices includes the following elements:

• Pressure gauge. Designed for visual monitoring of the heating system operation;
• Air vent. If the water temperature exceeds 100 degrees, excess steam acts on the valve seat of the device, releasing air from the pipes;
• Safety valve. It works in the same way as a water drain, but is needed to drain excess coolant from the pipes.

How to adjust a heating radiator using this unit? Alas, it is designed to prevent emergency situations throughout the entire system. Batteries require another device to be installed.

Mayevsky crane

Structurally, it is similar to a safety valve. A special feature is its small size and the ability to be mounted on a radiator pipe with a small diameter.

In order to correctly adjust heating radiators, you need to know in what cases the Mayevsky tap is used:

• Eliminating air pockets in radiators. By opening the valve, air is released until the coolant flows;
• Setting the critical pressure value parameters. If an emergency expansion of water occurs, the valve opens and the pressure in the radiator stabilizes.

Design of the Mayevsky crane

The last function is optional and is most often not used. This task is best handled by the security team. Proper adjustment of heating in the house should include all of the above elements.

When independently regulating a two-pipe heating system while the boiler is running, you need to constantly monitor the readings of thermometers and pressure gauges.

How does automation work?

A thermostatic three-way valve for underfloor heating is connected in front of the manifold. A certain temperature heating mode is set on the sensor. The device starts working when the parameters are changed.

When using servo drives, a device that operates from the network is connected to the mixing valve for heated floors. The sensor heats up and closes the electrical circuit. The plate is heated, which in turn transfers heat to the thermal fluid. It expands, pressing on the rod, which makes the poppet valves work.

We recommend: How to install cable heated floors?

When using a servo drive, the heating system changes operating mode within 3 minutes. If you use a thermal head as an automatic device, it will take up to 15 minutes to heat the liquid in the thermostat.

The operating principle of a two-way valve for underfloor heating is somewhat different. When the temperature in the main increases, the thermostat causes poppet valves or a ball device to operate, which completely blocks the outlet for hot water. The cooled coolant from the return pipe returns to the floor circuit.

When the temperature decreases, the valve opens hot water and closes the return flow. There is no mixing of the liquid. The principle of operation of a two-way thermostatic valve for underfloor heating is identical to manual switching of valves, but the system operates in automatic mode.

A three-way thermostatic valve for underfloor heating is installed in a heating system for a large heating area. The equipment is necessary for a boiler that heats water to a high temperature. A two-way valve is connected to the system as additional heating control for individual rooms.

Equipment for automatic control of the heating mode can be installed in a single-circuit or double-circuit heating system. This is convenient when using various types of heating, radiator and floor. The mixer is connected before the circulation pump. I recommend installing a water filter first. When connecting, use the threaded installation method.

Pressure, water speed and return temperature in the heating system

Basically, the requirements for heating systems imply dividing the specifics of heating into two types:

• independent, here the source of heat energy is located directly in the room - used in an individual house or in multi-storey buildings of an elite type;
• dependent, where a network of pipelines is connected to the heating complex - used in most houses in the urban area and urban-type settlements.

Due to the specific nature of the circulation of the coolant, water is predominantly used, where the speed of water in the heating system directly affects the temperature in the radiators. Circulation is divided into natural (based on the principle of gravity) and forced (heating system using a pump). According to distribution, it is customary to distinguish between a heating system with lower and upper pipe distribution.

Temperature

Despite the wide selection of heating systems provided, the options for heat supply and return are quite limited. The maximum temperature in the heating system must also be set according to the rules in order to avoid further malfunctions.

Radiators are connected to the heating system in one of three ways: bottom, side or diagonal.

Also, the lower connection is also called differently: “Leningradka”, saddle. According to this scheme, the return and supply are installed at the bottom of the battery. In most cases, it is used when pipes are laid under the baseboard or under the floor surface. The return temperature in the heating system should not differ from the supply temperature.

Water speed

If there are few sections, heat transfer will be extremely ineffective compared to other schemes - the speed of water in the heating system decreases, which leads to heat loss.

Side heating is the most popular type of connecting radiator batteries to heating. The supply of water as a heat carrier is carried out in the upper part, and the return is connected from below, so that the return temperature in the heating system is considered equal.

To avoid a decrease in the efficiency of this type of connection when increasing the radiator sections, it is recommended to install an injection tube.

Pressure

The diagonal type of connection is also called a side cross circuit, because the water supply is connected at the top of the radiator, and the return is organized at the bottom of the opposite side. It is advisable to use it when connecting a significant number of sections - with a small number, the pressure in the heating system increases sharply, which can lead to undesirable results, that is, heat transfer can be halved.

To finally settle on one of the options for connecting radiator batteries, you must be guided by the methodology for organizing the return flow. It can be of the following types: single-pipe, double-pipe and hybrid.

The option you should choose will directly depend on a combination of factors. It is necessary to take into account the number of floors of the building, where the heating is connected, the requirements for the price equivalent of the heating system, what type of circulation is used in the coolant, the parameters of the radiator batteries, their dimensions and much more.

Most often, their choice is made on a single-pipe heating pipe layout.

As practice shows, such a scheme is used precisely in modern high-rise buildings.

Such a system has a number of characteristics: they are low in cost, fairly easy to install, and the coolant (hot water) is supplied from above when choosing a vertical heating system.

Also, radiators are connected to the heating system in series type, and this, in turn, does not require a separate riser for organizing the return. In other words, water, having passed the first radiator, flows into the next, then into the third, and so on.

However, there is no way to regulate the uniform heating of radiator batteries and its intensity; high coolant pressure is constantly recorded in them. The further the radiator is installed from the boiler, the more heat transfer decreases.

There is also another wiring method - a 2-pipe scheme, that is, a heating system with return. It is most often used in luxury housing or in individual homes.

Here is a pair of closed circuits, one of them is intended for supplying water to parallel-connected batteries, and the second is for draining it.

Hybrid wiring combines the two schemes described above. This could be a collector circuit, where an individual wiring branch is organized at each level.

Causes

As already mentioned, the bottom of any battery will be slightly cooler than its top. The level of heat transfer from any metal is quite high - the water manages to cool faster than it leaves the radiator sections. For this reason, a temperature difference occurs.

The problem can be diagnosed by the increase in temperature gap. The bottom of each section burns with cold, while the top part heats up (sometimes it is dangerous to touch the battery with your hands, the metal is so hot).

The most common causes of this condition are:

1. Slow circulation speed of the working fluid.
2. Incorrect connection (supply and return pipes were mixed up).

Violation of the correct installation scheme is not that uncommon. Many owners or unskilled craftsmen make mistakes when connecting pipes to batteries.

As for the circulation speed, it may drop already during operation. This happens for a variety of reasons, each of which requires immediate elimination.

Connection errors

Qualified craftsmen, of course, do not make such mistakes. But amateurs may well make mistakes when installing heating. Most often, the return line is connected to the upper branch pipe of the battery. In this case, the feed is attached to the bottom. As a result, the removal of fluid from the radiator is disrupted, its efficiency decreases, and the entire system does not function properly.

If you connect the supply pipe from below, water flows around the battery in a circle and leaves it, while individual sections do not fill or do not warm up. With the upper return line, the liquid cannot leave the inside of the structure, because the radiator is not able to create increased pressure and squeeze water out through the upper pipe.

When connected correctly, the working fluid enters from above and gradually flows through all sections of the radiator, going down. After which it enters the return line and is transported back to the heating boiler.

The error can be resolved quite simply:

1. All pipes are dismantled (disconnected from the pipes).
2. The correct connection diagram is ensured: supply from above, return from below.
3. All elements are attached to their proper places. After which the heating is started and its operation is checked.

The only difficulty is the danger of stopping the system during the cold season. Therefore, for new heating it is recommended to carry out testing before the first frost.

Speed ​​drop

There are three reasons for improper circulation:

1. Violations were made during installation, namely, the cross-sections of the pipes were narrowed.
2. The coolant moves too slowly within the system.
3. The room temperature is too low.

Slow circulation is typical for circuits without additional equipment. As soon as a pump is installed that provides forced circulation, the problem is completely solved.

The narrowing of the section occurs for several reasons. An old heating system can accumulate rust or scale. Or an adjustment valve with an inappropriate cross-sectional diameter was installed. Alternatively, the polypropylene pipes are soldered incorrectly.

In order to accurately determine the reason that caused poor heating of the radiators, it is necessary to carefully inspect the circuit and analyze its condition.

Radiator does not heat up

Most often, problems with normal heat transfer occur in heating radiators. This is explained by their specific design - the coolant does not move through one pipe, as in a transport line, but is distributed over several.

In what cases does the heating radiator not heat? There are several factors that directly affect the correct operation of the battery.

Air locks in heating

There are several reasons for the appearance of air locks in the heating system - excess temperature, water evaporation, etc.

It is important that the consequence of this is the appearance of places in the line that are not filled with coolant. Most often these are heating radiators. To eliminate them, it is necessary to install a Mayevsky valve - an air valve that releases excess air from the device

To eliminate them, it is necessary to install a Mayevsky valve - an air valve that releases excess air from the device.

How to determine why a radiator does not heat well? The simplest method is a temperature difference on the surface. At the point where the air lock forms, it will be significantly lower, thereby preventing the normal passage of the coolant. To eliminate it, you must perform the following steps:

• Using a screwdriver or a rotary lever, the Mayevsky tap is opened;
• Add water to the system until the coolant begins to flow out of the tap along with the air;
• Shut off the water supply.

After starting the heating system, the surface of the radiator should heat evenly. Otherwise, repeat the procedure.

Improper installation and limescale deposits in pipes

The efficiency of its operation depends on the correct installation of the radiator. It should not be inclined relative to the plane of the floor and wall. If this condition has not been met, then the question will inevitably arise - why the heating battery does not heat.

To check the correct installation of the radiator, you can take a standard building level. If the upper plane of the battery has deviations, re-installation should be performed. It is best to use new reinforced fasteners for this.

If after this the question of why the heating radiator does not heat remains unresolved, it is recommended to flush the heating system. This problem is relevant for old pipes and radiators made of steel and cast iron. Over time, a limescale layer accumulates on the inner surface, preventing the normal flow of coolant. There are several ways to perform the washing procedure:

• Hydraulic. A special pump is connected to the system circuit, which creates high water pressure. Under the influence of this force, the scale is broken into small fractions and retained in the pump filter;
• Chemical. Special additives act on limescale, which loses its uniformity and flakes off from the inner surface. Subsequently, hydraulic flushing is performed to remove residual debris.

Experts recommend using a comprehensive method to solve the problem in which the radiator does not heat up. After checking the correct installation, the system is flushed, and then filled correctly with the Mayevsky tap open.

If a two-pipe heating system does not heat due to clogged pipes, you need to carefully choose a cleaning technology. For pipelines made of polypropylene, chemical cleaning cannot be done.

What Causes Return Problems?

Of course, first of all, you should consider what reasons may cause problems with the return line.

These include:

• Poor water pressure;
• Inappropriate pipe diameter (less than the established norm) through which water is supplied;
• Improper installation and installation of pipes;
• System clogged.

When a cold return is detected, it is recommended to first pay attention to the water pressure inside the system. In order for the return to work as it should, the system must be designed in such a way that water continuously circulates within the circuit.

When the speed of water pushing decreases, the coolants will not be able to push cold water through in a timely manner. This in turn will cause the batteries to cool down. Rooms on the upper floors of houses are most susceptible to the problem of insufficient water pressure.

The second most common problem is a clogged system. Unfortunately, cleaning of heating pipes in multi-storey buildings is carried out much less frequently than required by the rules. Consequently, sediment settles inside the pipes, which over time clogs the circuit and causes poor water permeability, significantly reducing its speed.

It is believed that the most problematic reason is poor heating installation. That is, when an inexperienced beginner takes on the installation and laying of pipes, without the necessary knowledge, there is always a risk that he may make a mistake somewhere or select elements that do not fit together in size. That is why it is advisable to seek the services of specialists.

Consumer choice: cast iron or aluminum

The aesthetics of cast iron radiators is the talk of the town. They require periodic painting, since the rules require that the working surface have a smooth surface 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 excellent:

• are slightly susceptible to water corrosion and can be used for more than 45 years;
• have high thermal power per section, therefore they are compact;
• are inert in heat transfer, so they smooth out temperature changes in the room well.

Another type of radiator is made of aluminum. Lightweight, factory-painted design, does not require painting, and is easy to maintain.

But there is a drawback that overshadows the advantages - corrosion in an 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, and when excess gas pressure is created, the aluminum device may burst.

The temperature standards for 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 strictly not recommended to increase the aesthetics of the room with shields in front of the heating device.

Automatic temperature control of TP

Automatic adjustment of a heated floor can be carried out thermomechanically or electronically using electromechanical actuators that control the operation of shut-off valves.

Thermomechanical control system

It is based on the operation of thermostatic valves or taps with thermal heads that respond to changes in coolant temperature. Various models of such shut-off and control valves are offered today by many manufacturers, for example, Oventrop. However, regardless of the name and type of thermosetting substance used in them (liquid or gas), these are thermomechanical self-regulating mechanisms that are most appropriately installed to control the temperature of one, individual circuit.

The operating principle of thermal valves is simple, which makes them very reliable and fault-tolerant. A copper, brass or bronze core installed in the device body, heated by the passing coolant flow, transfers the temperature to the thermosetting filler. In turn, the thermosetting element, which increases in volume, pushes the core, which, by moving the valve, gradually blocks the circulation of the heated liquid.

The thermostatic valve for heated floors, in addition to being installed on the distribution comb, can be mounted in a separate “unibox” type assembly. Such assemblies also include automatic air vents, which, together with thermostats, are placed in compact boxes (boxes). The use of a “unibox” allows you to adjust the temperature in a separate branch of the TP without being tied to bulky manifold cabinets, which is especially convenient with a small number of circuits.

In addition, thermomechanical floor heating controllers can have remote air sensitive elements. They allow you to configure them to control the flow of coolant not according to its temperature, but according to the air temperature in the rooms. The principle of their operation is the same, only the thermosetting substance is much more sensitive. It is advisable to install an air thermal head for simultaneous control of several circuits in one room, where water underfloor heating is the only source of heating.

Electronic control system

It consists of electronic thermometers, a controller and electric drives (actuators, servos). Electric drive mechanisms can be attached to the mixing heads of conventional control valves (valves) or be part of their design. The change in coolant supply intensity is carried out in accordance with specified threshold values. The measuring medium for the temperature sensors of the automatic floor heating temperature controller can be both the coolant and the air in the premises.

Important! Such control equipment is quite expensive, but at the same time it is capable of providing optimal operating conditions for underfloor heating and maximum energy savings. In addition, electronic regulators allow programming of the TP with binding of its operating modes to different time periods, which guarantees the user maximum thermal comfort.

What is the difference between heating flow and return?

And so, let’s summarize the differences between supply and return in heating:

• Supply – coolant that flows through water pipes from a heat source. This could be an individual boiler or central heating of the house.
• Return water is water that, having passed through all the heating radiators, goes back to the heat source. Therefore, at the input of the system there is supply, and at the output there is return.
• It also differs in temperature. The feed is hotter than the return.
• Installation method. The water conduit that is attached to the top of the battery is the supply; the one that connects to the bottom is the return line.

First, let's look at a simple diagram:

In the diagram we see a boiler, two pipes, an expansion tank and a group of heating radiators. The red pipe through which hot water flows from the boiler to the radiators is called DIRECT. And the lower (blue) pipe through which colder water returns is called REVERSE. Knowing that when heated, all bodies expand (including water), an expansion tank is built into our system. It performs two functions at once: it is a reserve of water to replenish the system and excess water goes into it during expansion from heating. Water in this system is a coolant and therefore must circulate from the boiler to the radiators and back. Either a pump or, under certain conditions, the force of earth's gravity can force it to circulate. If everything is clear with the pump, then with gravity many may have difficulties and questions. We have dedicated a separate topic to them. For a deeper understanding of the process, let's look at the numbers. For example, the heat loss of a house is 10 kW. The operating mode of the heating system is stable, that is, the system neither warms up nor cools down. The temperature in the house does not rise or fall. This means that 10 kW is generated by the boiler and 10 kW is dissipated by the radiators. From a school physics course we know that to heat 1 kg of water by 1 degree we will need 4.19 kJ of heat. If we heat 1 kg of water by 1 degree every second, then we will need power

G=Q/(4.19*dT)=10/(4.19*10)=0.24 kg/sec.

When autumn confidently strides across the country, snow is flying above the Arctic Circle, and in the Urals night temperatures stay below 8 degrees, then the word form “heating season” sounds appropriate. People remember past winters and try to understand the normal temperature of the coolant in the heating system.

Prudent owners of individual buildings carefully inspect the valves and nozzles of boilers. By October 1, residents of an apartment building are waiting like Santa Claus for a plumber from the management company. The Lord of valves and valves brings warmth, and with it joy, fun and confidence in the future.

Answers from forum users and experts to the question: The supply is hot and the return is cold

...what battery do you mean? In a private house or in an apartment? If…

...for hot and cold water and it turns out we pay for cold water per month...

This means there are blockages in the system, everything needs to be cleared.

How many degrees should hot water supply and return be by law?

DHW should be at least 55.60 degrees. If the water is less than 52, bacteria form in the water and the water begins to smell.

In our apartment, we measured the temperature in the batteries with a thermal imager: supply +52, return +28. The temperature in the apartment is +20, and outside -6. If this is the norm, then how to wash in the bathtub if the towel dryer is icy. How can you heat an apartment with such batteries at a temperature of -20 outside? Everything is normal.

why am I cold bro

how to distinguish supply from return in central heating in order to bring it home

bimetallic battery is slightly warm. Embedded in the supply. Bypass and supply pipe are hot. Supply from below

Good evening! Why is it that when heating with a single-circuit AOGV the top is hot and the bottom is cold and one radiator is cold, in two rooms the top and radiators are barely warm, I live in a private wooden house

I have a question why the return supply is 80 degrees 30 degrees of one branch, but the cold return costs two Khoper-100 boilers, reducing 800 square meters of pressure 2 after the pump 3

Residential 5 storey building. The heating from the thermal power plant was turned on. SERVE - cold. The return is warm. They can’t find the reason. Everything is fine in the neighboring house. There are no violations on the route (like the supply and return lines were mixed up). What is the reason? Tell.

private house we can’t start the heating from the gas boiler the hot return doesn’t go any further what to do

private house we can’t start the heating from the gas boiler the hot return doesn’t go any further what to do

private house we can’t start the heating from the gas boiler the hot return doesn’t go any further what to do

After the upstairs neighbors changed the batteries, our return line does not warm up. The supply works fine, but the return after de-airing does not work at all. The neighbors insist that they have nothing to do with it, the emergency lights are of no use, what could be the matter? It's been 1.5 weeks without heating in the living room.

For some reason the batteries do not heat well, it is the return that is cold, tell us what the problem is and how to fix it.

If you have a problem, then I can solve it for you, the batteries do not heat well due to the fact that there is air, the return line is cold, that may be why.

the temperature between the supply and return
is large, I mean there is a difference, then you need to figure it out, it, in principle, should be like that, but not very large.
I advise you to call the housing and communal services department and check everything with a specialist. My supply is boiling and the return is a little warm

Hello, we have a problem with our boiler JUNKERS ZS23AE23/31, the water pressure constantly rises, this happens especially quickly when the heating is on, please tell me what could be the reason, where to look for a breakdown or a link where to read about it. My email [email protected]

Heating systems with natural circulation

The natural circulation heating system became widespread in the pre-war period due to its efficiency, simplicity and reliability. Most often, this type of heating system is used in dachas, as well as in country houses due to frequent power outages at such facilities. Such systems are conventionally divided into two types - with bottom and top water supply. To determine the choice of the type of heating system, it is necessary to consider their differences, characteristics and scope of application.

Schematic diagram of heating with natural coolant circulation

Heating systems with natural circulation

Best answers

SamTrest:

horizontal - the supply is closer to the wall, the return is correspondingly further away - this is in the basement, but in the apartment as it turns out (rules for the development of heating systems)

Solodky Vitaly:

There are no regulatory documents on this matter! But historically, it so happened that in horizontal sections the SUPPLY is from above, above the RETURN, and also with lateral and diagonal connections, the supply always enters the radiator from above, the return from below, with a bottom connection through monoblocks, the supply enters the radiator through the left tap, and the return through the right. On vertical sections, the feed can be either from the right or from the left, depending on how it was more convenient to lay down.

What does it depend on?

The temperature curve depends on two quantities:

outside air and coolant. Frosty weather leads to an increase in coolant temperature. When designing a central source, the size of the equipment, building and pipe size are taken into account.

The temperature leaving the boiler room is 90 degrees, so that at minus 23°C, the apartments are warm and have a value of 22°C. Then the return water returns to 70 degrees. Such standards correspond to normal and comfortable living in the house.

Analysis and adjustment of operating modes is carried out using a temperature diagram.

For example, the return of liquid with an elevated temperature will indicate high coolant costs. Underestimated data will be considered a consumption deficit.

Previously, for 10-story buildings, a scheme with calculated data of 95-70°C was introduced. The buildings above had their own chart of 105-70°C. Modern new buildings may have a different layout, at the discretion of the designer. More often, there are diagrams of 90-70°C, and maybe 80-60°C.

Temperature chart 95-70:

Temperature chart

The influence of the coolant supply method on the choice of control technology

Control of heating of water heated floors equipped with their own heat pumps occurs under conditions of continuous supply of coolant at high speed and in large volumes. Such systems use the admixture of cooled liquid to the supply stream to bring its energy parameters to the specified ones. The mixing is carried out in pumping and mixing units (PMU), which lower the temperature of the coolant from the primary high-temperature heating circuit to the design ones. Further adjustment of the temperature of the heated floor is carried out on the combs and has already been described above. NSU blocks provide optimal operating conditions for underfloor heating, and also allow it to be installed in unlimited areas.

However, with a small TP quadrature it is possible to avoid the use of expensive mixing units. The temperature of the coolant for the heated floor, in this case, is maintained by the method of limiting flows or by the RTL scheme. The functional principle of the circuit is the portion supply of coolant into the circuits. In each branch, the active element of the thermostatic valve, installed on the return line, having warmed up to the set temperature maximum, blocks the flow of working fluid. The heat gradually released by the coolant is dissipated in the concrete screed. After the system has cooled to the minimum temperature threshold, the valve opens and the batch feed cycle is repeated.

The simplicity of RTL control of underfloor heating makes it especially attractive. After all, it is enough to use a set of thermomechanical valves installed on the comb, or compact “unibox” type assemblies. However, when choosing an RTL scheme, you should not forget about its limitations:

Important! The use of pipes of different diameters in one system (on one collector) of underfloor heating with RTL control is strongly not recommended.

Warm like a battery

Let’s assume that the central network structures are reliably insulated along the entire route, the wind does not blow through attics, staircases and basements, and conscientious owners have insulated the doors and windows in the apartments.

Let's assume that the coolant in the riser complies with building code standards. It remains to find out what the normal temperature of the heating radiators in the apartment is. The indicator takes into account:

• outdoor air parameters and time of day;
• location of the apartment in the house plan;
• living or utility room in an apartment.

Therefore, attention: it is important not what the temperature of the heater is, but what the temperature of the air in the room is. During the day, in corner rooms the thermometer should show at least 20 °C, and in centrally located rooms 18 °C is allowed

During the day, in corner rooms the thermometer should show at least 20 °C, and in centrally located rooms 18 °C is allowed.

At night, air in the home is allowed to be 17 °C and 15 °C, respectively.

The boiler does not warm up completely

The reasons why the water floor is not fully heated by the boiler may be insufficient boiler power or an incorrectly selected pump.

Often, a problem with heating a water heated floor occurs immediately after installation and first start-up. To protect yourself from the risk of encountering such a situation, you must follow the requirements for putting the heating system into operation and be able to regulate it. It is recommended to periodically record how much energy is consumed and what temperature the heating system maintains.

Heating system

Why do you need an expansion tank?

Accommodates excess expanded coolant when it is heated. Without an expansion tank, the pressure may 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 coolant volume by 5%, the pressure in the circuit due to the air tank will increase slightly.

The volume of the tank is usually taken 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.

The correct installation of the tank is with the hose facing up. Then excess air will not 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 escape through them. Yes, it makes up a small part of the coolant volume; but a large change in volume is not necessary for the pressure gauge to register the change.
• Plastic and metal-plastic pipes may be slightly deformed under the influence of pressure. Combined with high water temperature, this process will speed up.
• The pressure in the heating system drops when the temperature of the coolant decreases. Thermal expansion, remember?
• Finally, minor leaks are easy to see only in centralized heating through rust marks. Water in a closed circuit is not so rich in iron, and the pipes in a private house are most often not made of steel; therefore, it is almost impossible to see traces of small leaks if the water has time to evaporate.

Why is a pressure drop in a closed circuit dangerous?

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

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

How to slow down the pressure drop

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

The internal volumes of several tanks are summed up; the greater the total amount of air in them, the smaller the pressure drop will cause a decrease in the volume of 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 in 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, the tank can be mounted on a straight section of pipe in front of it.

Ways to control the temperature of a heated floor

To ensure the specified requirements of sanitary and technological standards, user preferences, the heated floor can be adjusted using the following adjustment methods:

The starting points for changing system settings can be measurements of the coolant temperature in the supply or return distributors. Indeed, for water heating, unlike electric heating, it is not typical to install thermal sensors in the floor structure - they are mounted directly on the collectors. Most often, such sensors or sensitive elements are parts of thermostatic valves, through which the heated floor is adjusted.

Control signals to automatic devices can also come from air temperature sensors located in heated rooms.

Automatic temperature control of TP

Automatic adjustment of a heated floor can be carried out thermomechanically or electronically using electromechanical actuators that control the operation of shut-off valves.

Thermomechanical control system

It is based on the operation of thermostatic valves or taps with thermal heads that respond to changes in coolant temperature. Various models of such shut-off and control valves are offered today by many manufacturers, for example, Oventrop. However, regardless of the name and type of thermosetting substance used in them (liquid or gas), these are thermomechanical self-regulating mechanisms that are most appropriately installed to control the temperature of one, individual circuit.

The operating principle of thermal valves is simple, which makes them very reliable and fault-tolerant. A copper, brass or bronze core installed in the device body, heated by the passing coolant flow, transfers the temperature to the thermosetting filler. In turn, the thermosetting element, which increases in volume, pushes the core, which, by moving the valve, gradually blocks the circulation of the heated liquid.

The thermostatic valve for heated floors, in addition to being installed on the distribution comb, can be mounted in a separate “unibox” type assembly. Such assemblies also include automatic air vents, which, together with thermostats, are placed in compact boxes (boxes). The use of a “unibox” allows you to adjust the temperature in a separate branch of the TP without being tied to bulky manifold cabinets, which is especially convenient with a small number of circuits.

In addition, thermomechanical floor heating controllers can have remote air sensitive elements. They allow you to configure them to control the flow of coolant not according to its temperature, but according to the air temperature in the rooms. The principle of their operation is the same, only the thermosetting substance is much more sensitive. It is advisable to install an air thermal head for simultaneous control of several circuits in one room, where water underfloor heating is the only source of heating.

Electronic control system

It consists of electronic thermometers, a controller and electric drives (actuators, servos). Electric drive mechanisms can be attached to the mixing heads of conventional control valves (valves) or be part of their design. The change in coolant supply intensity is carried out in accordance with specified threshold values. The measuring medium for the temperature sensors of the automatic floor heating temperature controller can be both the coolant and the air in the premises.

Important! Such control equipment is quite expensive, but at the same time it is capable of providing optimal operating conditions for underfloor heating and maximum energy savings. In addition, electronic regulators allow programming of the TP with binding of its operating modes to different time periods, which guarantees the user maximum thermal comfort.

Source

Heating cable fault

We have already checked the thermostat and floor heating sensor, but the fault has not yet been found? We begin checking the heating cable. In order to determine the load created by the heating cable, it is necessary to measure its resistance. We compare the obtained data with the indicators specified in the technical data sheet of the device.

Based on the instrument readings, it is possible to determine the cause of the heated floor malfunction. Data below the standard indicates damage to the outer sheath of the heating cable. If the resistance tends to zero, the reason is mechanical damage to the cable or burnout of the coupling. Unstable values ​​indicate the presence of water under the shell. If the multimeter shows the “infinity” sign, the problem is a burnout or breakage of the heating element located in the coupling of the device.

Having carried out diagnostics and identified a malfunction of the heating system, you can fix it yourself, or seek the help of specialists. But you should definitely take into account that finding the place of damage to the heating cable in the screed is only possible with the help of special equipment. If such a situation arises, we advise you to contact a service center, whose technicians will repair the heating cable with minimal damage to the floor covering.

You can get advice, additional information about products and buy electric heated floors in our online store, by calling 8.0 or in one of the stores in your city.

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