The boiler is 70 degrees and the radiator is cold. The boiler is working, but the radiators are cold. Design of heated floors: general recommendations. Does the coolant affect the quality of heating?

2017-06-07 Evgeniy Fomenko

Why does the boiler not heat water for the heating system?

There can be many reasons why a gas boiler does not heat water for heating. We will consider the main ones and ways to eliminate these reasons below.

The boiler turns on, but the heating does not heat.

Possible reasons and their elimination:

It operates on the principle expansion tank without reducing the pressure in the system. After the unit has been idle for a long time, check the valve; it may become clogged with scale;

incorrectly selected battery design. The batteries must correspond to a specific heating mode, since each type of radiator has an individual heat transfer value depending on this mode.

The principle of operation of a double-circuit heating boiler

For example gas unit Let's look at the operating principle of a double-circuit boiler. The design of the unit is a system of blocks, the operation of which is interconnected and controlled by a security system, which includes various sensors. The main blocks are a gas block, where ignition and combustion occurs, a hydraulic block, which regulates the flow and pressure of liquid, and a smoke removal block, which removes gas combustion products.

When the boiler is turned on, the circulation pump is initially started, then gas is supplied using the gas valve. Automatic ignition ignites the gas, and as the gas burns, the heat exchanger heats up, heating the coolant passing through it. In this mode, the unit will work for some time until the parameters that are regulated by sensors change.

Sensors monitor the temperature in the room, in the return flow, gas pressure, system pressure, draft flow, and the presence of flame. Temperature sensors can regulate the inlet or outlet temperature heating circuit. If there is a sensor on the return when reaching set temperature The thermostat sends a signal to the electronic board, which, after processing it, turns off the gas supply.

In this case, the circulation pump will run for some time to cool the heat exchanger. This is done so that the remaining heat in the heat exchanger does not bring the coolant to a boil. After the water in the system has cooled to the set temperature, the electronic board will start the pump, gas valve will open the gas and the entire cycle of operation of the double-circuit boiler will repeat.

When opening a tap with hot water the flow sensor is activated and the control board switches the three-way valve to heat the secondary heat exchanger. Heating hot water in the system is a priority, i.e. immediately after you open the hot water tap, the entire system will only work to heat this water.

When the tap closes, the reverse process occurs - the board transmits a signal to the three-way valve, it closes the DHW system and the unit again starts working on the heating circuit. Please remember that it will take some time for the unit to start flowing from your tap. hot water.

Some devices are equipped with a “quick start” or “comfort” function. This function allows the boiler to switch the three-way valve from time to time and heat the water in the secondary coolant.

DHW does not heat up - causes and troubleshooting.

The most common reason why DHW does not heat up is severe scale formation inside the heat exchanger. Scale not only narrows the water flow in the heat exchanger, it significantly reduces the water temperature.

The reason for this is that the thermal conductivity of scale salts is many times less than the thermal conductivity of the metal from which the heat exchanger is made. The unit does not produce (does not supply) hot water or it flows poorly if a piece of plaque has broken off and blocked the flow of liquid.

Hot water does not flow into the tap when the flow sensor does not work. It is a fan that works when water flows through it. in this case, the signal from it is sent to the control board, which gives a command to heat the water. The sensor may become clogged; it can be cleaned without dismantling it.

The sensor is a cylinder located near the circulation pump. To clean, simply open and close the tap in front of the device. If this procedure does not produce results, you will have to dismantle it, clean it and put it in its original place. If the sensor is not working, you will have to replace it.

If the three-way valve is faulty, the unit will not produce hot water. The purpose of the three-way valve is to shut off the heating system when the hot water tap opens. When the valve does not switch, the boiler continues to heat water for heating.

The cause of a valve malfunction may be a simple blockage, for example, a piece of rust. If the problem is more serious, replace the valve with a new one. In addition, one of the simple reasons why hot water does not flow from the tap may be a clogged gas hose or gas filter.

Sectional view of a three-way valve

With heating this will not be so noticeable, but at the temperature of the water from the tap it will be more noticeable. Clean the hose and filters. Some of the points listed above may also be the causes of problems with heating and hot water in wood, electric and solid fuel (ST) boilers, provided the design details are similar.

It happens that the heating system malfunctions, and a situation arises - the boiler is working, but all the batteries, or at least part of them, are cold. Let's look at a dozen reasons for this state of affairs, how to fix the breakdowns yourself, without involving...

It's easier with automated boilers

If the boiler is automated, gas or electric, then, as a rule, the automation will not allow overheating of the coolant in the boiler itself when the supply to the batteries for some reason stops. The protections will turn off the device, show an error code, then you need to draw conclusions from this information.

A breakdown of the boiler itself can be repaired by service. It is not recommended to open complex equipment yourself.

Cold radiators, when an automated boiler is running, may occur not only due to the breakdown of complex equipment, but also because... (the most common reasons).

• Air pockets in radiators and on U-shaped elevations of the pipeline. Bleed the air using Mayevsky's taps. Install air vents; if they are not there, convert the system to “normal”.
• Clogged filter, silting of the lower section of the pipes. Check the return filter at the boiler inlet.

Wrong system

For example, in a parallel circuit, if the installation rules are violated, the middle radiators in the ring may turn out to be cold when the boiler is running. Eliminated by balancing or rewiring.

The following is also possible:

• The valves are closed - check the valves, including tuning and balancing valves, which regulated the flow along individual dead-end branches, to individual radiators.
• A sequential battery connection scheme was used, in which the last radiators in the pipe are always colder or do not heat up at all... Rework, use modern circuits.
• Various complex inclusions of radiators, “where everything is confusing.” Remodel and use conventional two-pipe heating systems - dead-end, passing, radial with the presence of balancing valves...

Pipe problems

Polypropylene pipes can create a surprise. When welding them, the internal clearances are not controlled. The installer does not guarantee anything. It is not uncommon for the boiler to heat up, but the polypropylene system is not working properly, some of the batteries are colder for some reason, some are disconnected...
First of all, start resoldering and finding the bottleneck. Or replace the pipes with more reliable ones.

• In any system, there is debris in the coolant. If there are U-shaped depressions in highways, there may be congestion.
• Perhaps just old steel pipes? Their service life is limited; from the inside they become overgrown with deposits and heating stops.

In systems without automation

There is a threat of a serious accident, destruction of the boiler if it is working and the batteries are cold. In a solid fuel heat generator, if the fuel is burning, the liquid in the heat exchanger will boil very quickly if there is no circulation and heat removal, i.e. if the heating system remains cold.

This is not an acceptable situation, which is prevented by installing an uninterruptible power supply for the circulation pump. And also by regularly checking the filter.

First of all, in such systems the operation of the circulation pump is checked, which is often located on the return line near the boiler.

Complex systems - what is the solution

Nowadays there are more and more complex heating systems. Such piping of a private house can be divided into several independent circuits, each of which has its own circulation pump. For example: - radiators of a house, heated floors in a house, an indirect heating boiler, a greenhouse, a garage and a workshop, an outbuilding, and a separate attic.

It’s not uncommon for something like this to be connected to a couple of working boilers (the backup one doesn’t count).

To complex circuit worked stably, all these circuits must be connected to some kind of distributor that would provide them with the same initial stable pressure, regardless of the operation of neighboring circuits. IN complex systems(more than 4 circuits) this is done using a hydraulic arrow or a primary circulation ring of pipes.

Incompetent design or installation under such circumstances leads to the fact that some of the pipelines and batteries remain cold when the boiler is running. Those. one circuit influences the other. The solution is to create a competent scheme.

Situations in apartments

In apartments with central heating everything is simpler. The heating circuit there is not complicated - one or more radiators are connected in parallel to the risers.

• If the riser is cold, it means that the air at the top has not been vented, or the distribution along the risers has not been adjusted. In any case, you need to contact someone to bleed and adjust...
• If the riser is hot and the edge of the battery is cold, then there can be two reasons - the batteries are airy, and you need to bleed the air yourself. Or - a small pressure on the riser - you need to understand it as in the previous paragraph.
• There is also a common problem in apartments - clogging, overgrowing of old cast iron radiators. It also happens that it’s time to change them for new ones, otherwise nothing will help...

Removing cold batteries according to the above descriptions for all reasons, of course, requires certain qualifications. If you can’t do it yourself, then you need to call specialists. Particular care must be taken when handling battery plugs in apartments, since any violation of the system threatens an accident, boiling water, flooding of apartments...

Change temperature regime Heating malfunctions can be caused by a number of internal reasons. Many of them negatively affect the efficiency of the system, increasing energy costs. In such cases, a reasonable question arises: why does the heating not heat up: radiators, batteries, pumps, systems? The first step is to find the causes of the problem.

Common heating problems

The operating principle of any heating system is the efficient transfer of thermal energy from the energy carrier (gas, solid fuel, diesel, etc.) water in pipes. The task of heating devices (radiators, radiators, pipes) is to transfer the resulting heat into the room.

And if the heating radiator does not heat, the reasons for this may lie both in the design itself and in the parameters of the system as a whole. Let's consider the common reasons for a decrease in the efficiency of a heating system:

• Low efficiency of the boiler heat exchanger. The water does not heat up to the required temperature;
• A particular radiator does not heat well. Possible reasons: improper installation, formation of air pockets;
• Change technical characteristics systems - an increase in hydrodynamic resistance in certain sections of the pipeline, a decrease in the bore diameter of pipes, etc. Most often, the consequence of such phenomena is that the heating circulation pump gets very hot.

In some cases, not one, but several of the listed problems arise. Often the main one is the root cause of the appearance of the following ones. Thus, the formation of an air lock affects the increase in hydrodynamic resistance, and as a result, an increased load on the circulation pump occurs.

Decorative grilles should not be installed on a heating radiator with poor heating or covered with a panel. Thus, the already low efficiency of its work will be artificially reduced.

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.

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.

For normal heating of the radiator, you need to install an adjustable thermostat. Depending on the set temperature, it will automatically adjust the volume of coolant.

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

The boiler does not heat the radiators

Often, a two-pipe heating system does not heat due to the low heat transfer rate of the boiler exchange circuit. This leads to a decrease in temperature and, as a consequence, a loss of efficiency of the entire system. Not every boiler model provides an easy way to dismantle the heat exchanger. If the heating does not heat well due to the appearance of plaque on the internal elements of the boiler, you can perform flushing without this procedure. To do this you will need a pump with a filtration system. The cleaning procedure is as follows:

• Disconnecting the boiler from common system heating;
• Connection to the inlet and outlet pipes of the pump hoses;
• Filling a special cleaning liquid into the boiler heat exchanger;
• By using centrifugal pump the speed of liquid passage through the boiler increases.

After this, the radiators should not heat up poorly. Special attention should be given to the washing liquid. It should not harm the metal elements of the boiler and system. Therefore, at the end of the procedure, the entire system should be rinsed with distilled water.

To avoid the appearance of scale, before pouring water into the heating system, you need to reduce its hardness level. Usage running water not recommended as it contains a large number of calcium and magnesium bicarbonates. They are the main source of appearance limescale not only in the boiler heat exchanger, but also in pipes and radiators.

The best way to clean the heat exchanger is to dismantle it. This way you can not only remove the entire volume of scale, but also ensure its integrity. After this procedure, the heating system should not heat poorly.

Pipelines: reasons for low heating

Failures in heating mode are typical two-pipe system heating. In this case, the supply line that distributes the coolant to the radiators does not heat. Identification of the “problem” area can be done by measuring the temperature on the surface of the pipes or a thermal imager.

Natural circulation

What could cause such problems? If the heating does not heat well, the slope of the line may not be observed. This only applies to natural circulation systems. According to the standards, the slope of the pipes should be 10 mm per 1 m.p. In addition, the direction is taken into account - from the accelerating riser to the radiators. For the return pipe, the slope must be towards the boiler.

At the first stage, you need to use building level measure this indicator. If it meets the standard, but the heating radiator does not heat, there is a possibility of air pockets forming. In this case, an integrated approach is recommended, which includes the following steps:

• Measuring the angle of inclination. If necessary, change it to the required value;
• Flushing pipes to remove limescale;
• Filling the system with coolant with open Mayevsky taps on the radiators.

This technique will eliminate the low heat transfer rate of the heating system.

To improve circulation in open systems you can install a circulation pump. If it overheats, you need to install an additional one. This is often necessary for branched heating systems.

Forced coolant circulation

For a system with forced movement of water in pipes, the formation of air locks can be avoided by using an air vent installed at the top of the system. In part, it performs the functions of an open expansion tank, but it does not reduce the pressure in the pipes to a critical level. Its absence is an indirect cause of poor heating of the radiator.

The specificity of closed heating systems is that it is not necessary to comply with the installation level of the pipes. However, when the critical heating level of the coolant is exceeded, steam is released, which is the main cause of air locks. Since air has a lower density than water, it will concentrate in the upper region of the pipeline sections. If the heating radiators do not heat well closed system– the reason may be a decrease in the volume of coolant in the pipes due to air resistance.

What needs to be done in this case? First of all, check the functionality of the air vents. If the valve is idle for a long time, it may become covered with limescale, which makes it impossible to open it under air pressure.

In private homes, it is not uncommon for the radiators to remain cold but the boiler to work. There are many influencing factors here, let’s divide them into groups and analyze the reasons.

Blockage in pipes

• You need to check the dirt filter on the return line to the boiler first. For any heating problems, this is the first action.
• There may be air pockets in the system at elevated points. U-shaped contours, radiators must be equipped with Mayevsky taps. Do I need to bleed the air?..

• There may be debris blockages in pipe depressions, in Y-shaped depressions or in the lower part of radiators. Such a violation is not easy to eliminate, since it requires disassembling the pipes and flushing. Usually done in sections through the lower radiator caps that have been unscrewed...

Reduced pipe cross-section

Another common reason that radiators, or part of them, remain cold when the boiler is running is increased hydraulic resistance, as in previous cases, but created by problems that cannot be eliminated by cleaning.

• Are all the taps open and are the balancing valves in the correct position? Often the cause of cold radiators is a simply closed tap.
• Polypropylene pipelines may have a reduced cross-section due to improper soldering. If the newly assembled polypropylene system does not work correctly, then the reason is most likely due to internal deposits. It is necessary to redo the narrowed branch or replace it with metal-plastic.

• Steel pipes can simply corrode significantly and reduce the clearance inside. There are already a few of them in use, but where they exist, the radiators are often underheated...

How boilers react to system disturbances

• Automated boiler, with a decrease in coolant flow in the system, i.e. When the batteries, or parts thereof, are cold, they will turn on more often, quickly rise to temperature, and turn off. Or it may even show an error - boiling if the coolant stops due to a dirt filter, for example.
• The solid fuel boiler cannot stop burning and cannot show an error. It is saved from a situation with a complete cessation of water movement by an emergency circulation scheme by gravity or replenishment with cold coolant from the tank... Redundancy of the power supply to the pump by an uninterruptible power supply must also be implemented.

Thus, the primary sign that something is wrong with the heating system is overheating of the boilers. After such incidents, it is already necessary to look for the reason for the suspension of movement or the decrease in coolant consumption.

Distribution violations

The reason for cool radiators when the boiler is running may be improper installation of complex systems.

• Many circuits with their own pumps - a garage, an outbuilding, a hut, a greenhouse... - are switched on “bump-bang-parallel” without equalizing the initial pressure. We need to make a system according classical schemes with a hydraulic arrow or with primary-secondary rings.

• The Tichelman loop was made with violations (with non-compliance with the same pipe diameter and the same conditions for connecting radiators), so the middle radiators in the ring are cold. The system needs to be rewired.
• The underfloor heating circuits do not work - the connection is mixed up - “2 times for return or supply.” The same is true in a radial circuit or on a distribution common collector.
• The RTL tap is installed on the supply side, so it is always closed at any temperature settings.
• Three-way and two-way valves and check valves are installed “upside down”.

Instruments and automation are out of order

Several cases of equipment breakdowns that occur in private homes.

• In schemes with a solid fuel boiler, with a buffer tank, hydraulic arrows, and heated floors, thermal heads with three-way valves—temperature regulators—do not work adequately. It is necessary to check the temperatures in the circuit near the regulators and the operation of the thermal heads, and replace the equipment.
• Also with thermal heads on separate radiators.

• The servo drives for the electric control of the mixing valves - temperature regulators - do not work.
• Indoor thermostats and weather-dependent automation do not work, there are no control signals to regulate the temperature of the coolant.

• Pumps on individual circuits do not work.
• The automatic air vent does not work - airing the riser, collector or boiler...

As you can see, there is something to work on... More often, if the blockage or airing is not identified and eliminated by primary efforts, consumers turn to specialists, and the issue is gradually resolved...

Cats don't sleep on cold radiators.

Boiler malfunctions

Typical problems with the operation of heating equipment:

• malfunction of the built-in pump;
• the heat exchanger is clogged;
• The three-way valve does not work.

If the boiler is working and the radiators are cold, experts recommend, first of all, assessing the technical condition of the main heating element. More specifically, to establish whether the built-in device works . This part is a permanent attribute modern equipment and is designed to improve the efficiency of its work. Very often, after a long period of inactivity in the summer, the pump can become clogged or become covered with a layer of limescale. As a result, it does not remove the heated coolant from the heat exchanger in a timely manner. The boiler is boiling, but the radiators are cold.

It is strictly prohibited to independently repair such complex equipment as a boiler. In this case, either a specialist from the service center or a repairman with the appropriate certificate or permit is called to your home.

Experts do not recommend using ordinary, tap water because she is tough. When the coolant temperature increases, dissolved salts settle on the heat exchanger. As a result, the following problem arises: the boiler is working, but the radiators are barely warm. Scale reduces the thermal conductivity of the heat exchanger, so the water in the circuit does not heat up, although the heating element constantly works with excessive energy consumption. You can fix the problem by changing the coolant and cleaning the heat exchanger. This video will help you understand how to clean the heat exchanger correctly:

A double-circuit boiler heats water, but does not heat the radiators. Here you need to pay attention to the serviceability of the three-way electric valve. It is responsible for switching the bypass from heating circuit maintenance mode to DHW and CO mode.

Problems with the heating circuit

The pump must be selected according to the requirements of the heating circuit.

Malfunctions in the operating mode of the heating circuit are not always associated with a malfunction of the main heating element. If the boiler works, but does not heat the batteries, the reason must be sought in the wiring itself.

List of main heating circuit malfunctions:

• the filter on the return line or the needle tap (Maevsky tap) is clogged;
• insufficient power of the circulation pump;
• the rules for installing a heating circuit with natural circulation have not been followed.

Any of the above problems must be resolved before starting heating season. Otherwise, the room may be left without heat for several days, since the repair involves completely draining the coolant.

So, why doesn’t the boiler heat the batteries if everything worked fine over the previous years? The reason is a dirt plug that has formed on the heating circuit filter and completely blocks the coolant flow. It can be solved simply - the water is drained from the pipes or its circulation is blocked using bypasses, and the filter is cleaned. To prevent a recurrence of such a situation, it is necessary to completely replace the coolant with parallel .

In a gravity system, the slope of the pipes is key.

The second reason why the boiler works but the radiators are cold is the insufficient power of the circulation pump. The performance of the device is not enough to pump the entire volume of coolant in a timely and efficient manner. Or the heating system in the house has branches that are located at a significant distance from the pump. As a result, the circulation pump overheats, the heating equipment operates with excessive energy consumption, and the radiators remain cold. The solution is to change the coolant pumping device to a more powerful one.

If the house has a two-pipe heating circuit with natural circulation of water, and during the heating season it is often noticed that the boiler is on and the radiators are cold, then the reason lies in non-compliance with the slope of the main line. According to regulatory documentation, only the slope of the pipes is equal to 10 mm for each linear meter in a heating system with natural circulation will ensure normal movement of coolant. The result is uniform heating of the batteries throughout the house. If there is no slope, the coolant stagnates, which negatively affects the temperature of the radiators. The problem can be solved by completely redoing the wiring.

Why are the radiators cold when the boiler is running?

Low efficiency of the heating system can be the result of malfunctions of both the circuit itself and the main heating element. In the case of a heating device, it is necessary to pay attention to the three-way valve, the functionality of the pump and the technical condition of the heat exchanger. Typical problems for heating wiring are a clogged filter, insufficient power of the circulation pump and lack of slope of the pipes of the circuit with natural water circulation.