The boiler is 70 degrees and the radiator is cold. The boiler is working, but the batteries are cold. Designing underfloor heating: general recommendations. Does the coolant affect the quality of heating

2017-06-07 Evgeny Fomenko

Why the boiler does not heat water for the heating system

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

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

Possible reasons and their removal:

It functions according to the principle expansion tank without reducing the pressure in the system. After a long downtime of the unit, check the valve, it may become clogged with scale;

wrong battery design. 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 consider the principle of operation 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 the gas block, where ignition and combustion take place, the hydraulic block, which regulates the supply and pressure of the liquid, the smoke exhaust block, which removes the products of gas combustion.

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, in the process of gas combustion 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 controlled by the sensors change.

The sensors monitor the temperature in the room, in the return flow, gas pressure, system pressure, draft flow, flame presence. Temperature sensors can control 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, having processed it, turns off the gas supply.

In this case, the circulation pump will work for some more time in order 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 cooling to the set water temperature in the system, 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 be repeated.

When opening a faucet with hot water the flow sensor is triggered and the control board switches the three-way valve to heat the secondary heat exchanger. The heating of hot water in the system is a priority, i.e. immediately after you open a 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. It should be remembered that the unit will take some time for it to flow from your faucet. hot water.

Some appliances 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 heating medium.

DHW does not heat up - causes and troubleshooting.

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

The reason for this is 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 give (does not supply) hot water or it runs weakly if a piece of plaque has broken off and blocked the fluid flow.

Hot water does not flow to the faucet when the flow sensor does not work. It is a fan that works when water flows through it. while the signal from it goes to the control board, it gives a command to heat the water. the sensor can become clogged, it can be cleaned without dismantling.

The sensor is a cylinder located near the circulation pump. To clean, simply open and close the tap in front of the appliance. If this procedure does not work, 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 change 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 a hot water tap is opened. When the valve does not switch, the boiler continues to heat water for heating.

The cause of a valve malfunction may be an elementary 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 run from the tap may be clogging of the gas hoses or gas filter.

Three-way valve in section

On heating, this will not be so imperceptible, but on the temperature of the water from the tap it will be felt more significantly. Clean hose and filters. Some of the points listed above can also cause problems with heating and hot water in wood, electric and solid fuel (TT) boilers, provided that the design details are similar.

It happens that the heating system fails, and a situation arises - the boiler is working, and all the batteries, or at least part of them, are cold. Consider a dozen reasons for this state of affairs, how to fix breakdowns on your own, 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 the coolant to overheat 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 conclusions must be drawn from this information.

The breakdown of the boiler itself is eliminated by service. Opening complex equipment yourself is not recommended.

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

• Air locks in radiators and on U-shaped elevations of the pipeline. Release the air with Mayevsky's taps. Install air vents, if not, remake 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 passing scheme, 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 adjusting, balancing, which regulated the flow through individual dead-end branches, to individual radiators.
• A serial battery connection scheme was used, in which the last radiators along the pipe are always colder or do not heat at all ... Remake, apply modern schemes.
• Various complex inclusions of radiators, "where everything is confusing." To remake the use of conventional two-pipe heating systems - dead-end, passing, beam with the presence of balancing valves ...

Pipe problems

Polypropylene pipes can create a surprise. When welding, internal gaps are not controlled. The installer guarantees nothing. It is not uncommon for the boiler to heat up, but the polypropylene system does not work normally, for some reason some of the batteries are colder, some are turned off ...
First of all, do soldering and find a bottleneck. Or replace the pipes with more reliable ones.

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

In systems without automation

There is a threat of a serious accident, the destruction of the boiler if it works and the batteries are cold. In a solid fuel heat generator, in the presence of fuel combustion, the liquid will boil very quickly in the heat exchanger 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. Also check the filter regularly.

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

Now 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 at home, underfloor heating in the house, indirect heating boiler, greenhouse, garage and workshop, outbuilding, separately - attic.

Not infrequently, this is connected to a couple of working boilers (the backup does not count).

To complex scheme 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.

An illiterate design or installation under such circumstances leads to the fact that when the boiler is running, part of the pipelines and batteries remain cold. Those. one circuit influences another. The way out is to create a competent scheme.

Situations in apartments

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

• If the riser is cold, then the air was not bled at the top, or the distribution over the risers was not adjusted. In any case, you need to contact someone to play off and adjust ...
• If the riser is hot and the edge of the battery is cold, then there can be two reasons - airing the battery, while you need to bleed the air yourself. Or - a small pressure on the riser - you need to understand as in the previous paragraph.
• In apartments, there is also a common problem - clogging, overgrowth of old cast iron radiators. It also happens that it is time to change them for new ones, otherwise nothing will help ...

Eliminating cold batteries as described above for all reasons, of course, requires some skill. If it doesn’t work on your own, then you need to call specialists. Particular care must be taken with battery plugs in apartments, since any violation of the system threatens with an accident, boiling water, flooding of apartments ....

Change temperature regime heating operation can be caused by a number of internal causes. 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.

General heating problems

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

And if the heating battery does not heat up, the reasons for this may lie both in the design itself and in the parameters of the system as a whole. Consider the common reasons for the decrease in the efficiency of the heating system:

• Low efficiency of the boiler heat exchanger. Water is not heated to the desired temperature;
• A specific heating battery does not heat well. Possible reasons - improper installation, the formation of air pockets;
• Change specifications systems - an increase in hydrodynamic resistance in certain sections of the pipeline, a decrease in the passage diameter of pipes, etc. Most often, the consequence of such phenomena is that the heating circulation pump is very hot.

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

Do not install decorative grilles or cover it with a panel on a radiator with poor heating. Thus, even so, the small efficiency of its work will be artificially reduced.

The radiator does not heat up

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

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

Air pockets in heating

There are several reasons for the appearance of air pockets in the heating system - exceeding the temperature regime, 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 radiators. To eliminate them, it is necessary to install a Mayevsky crane - an air valve that releases excess air from the device.

How to determine why the heating radiator does not heat well? The simplest method is the temperature difference on the surface. In the place of formation of an air lock, it will be much lower, thereby preventing the normal passage of the coolant. To fix it, follow these steps:

• With the help of 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 together with 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 heating radiator, you need to install an adjusting thermostat. Depending on the set temperature mode, it will automatically adjust the volume of the coolant.

Incorrect installation and limescale 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 up.

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 mounts for this.

If, after this, the question of why the heating radiator does not heat up 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 on inner surface a lime layer accumulates, preventing the normal flow of the coolant. There are several ways to perform the flushing procedure:

• Hydraulic. A special pump is connected to the system circuit, which creates a large pressure of water. 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 the inner surface. Subsequently, hydraulic flushing is performed to remove residual debris.

Experts recommend using an integrated method to solve the problem in which the heating battery does not heat up. After checking the correctness of the installation, the system is flushed, and then the correct filling is performed 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 batteries

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 the temperature regime and, as a result, a loss in the efficiency of the entire system. Not every boiler model provides for 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 flush without this procedure. To do this, you need a pump with a filtration system. The procedure for cleaning is as follows:

• Switching off the boiler common system heating;
• Connection to the inlet and outlet pipe of the pump hoses;
• Filling a special cleaning liquid into the boiler heat exchanger;
• By using centrifugal pump the rate of passage of liquid through the boiler increases.

After that, the heating batteries should not heat up badly. Special attention should be given to the flushing liquid. It must not harm the metal elements of the boiler and the system. Therefore, at the end of the procedure, rinse the entire system with distilled water.

To avoid the appearance of scale, before pouring water into the heating system, it is necessary to reduce its hardness index. Usage running water not recommended as it contains a large number of bicarbonates of calcium and magnesium. They are the main source of 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. So you can not only remove the entire amount of scale, but also make sure its integrity. After this procedure, the heating system should not heat up badly.

Pipelines: causes of low heating

Failures in the heating mode are characteristic two-pipe system heating. In this case, the supply line does not heat, distributing the coolant to the radiators. Identification of the "problem" zone can be done by measuring the temperature on the surface of pipes or a thermal imager.

natural circulation

What could be causing such problems? If the heating does not heat well, the slope of the main line may not be observed. This only applies to systems with natural circulation. According to the standards, the slope of the pipes should be 10 mm per 1 r.m. 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.

The first step is to use building level measure this figure. If it corresponds to the norm, but the heating radiator does not heat, there is a possibility of air locks. In this case, an integrated approach is recommended, which includes the following steps:

• Tilt angle measurement. If necessary, change it to the required indicator;
• Flushing pipes to remove limescale;
• Filling the system with coolant with open Mayevsky taps on radiators.

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

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

Forced coolant circulation

For a system with forced movement of water in the pipes, the formation of air pockets 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 heating radiator.

The specificity of closed heating systems lies in the optional observance of the level of pipe installation. However, when the critical level of heating 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 in 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 performance of the air vents. If the valve is left idle for a long time, the valve may become covered with limescale, which makes it impossible to open it with air pressure.

In private houses, it is not uncommon for the radiators to remain cold and the boiler to work. There are many influencing factors, we will divide them into groups and analyze the reasons.

Blockage in pipes

• It is necessary to check the dirt filter on the return before the boiler first. For any violations of heating, this is the first action.
• It is possible that there is air in the system at elevated points. U-shaped contours, radiators must be equipped with Mayevsky cranes. Do I need to bleed air?

• There may be debris blockages in pipe sinks, Y-shaped sinks, or at the bottom of radiators. Such a violation is not easy to eliminate, since disassembly of pipes and flushing is necessary. Usually done in sections through unscrewed lower radiator plugs ...

Reduced pipe 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 already created by malfunctions that cannot be eliminated by cleaning.

• Are all the taps open, are the balancing valves in the right position? Often the cause of cold radiators is a trite closed faucet.
• Polypropylene pipelines may have a reduced section due to improper soldering. If the newly assembled polypropylene system does not work correctly, then the reason is more likely in 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 operation, but where they are, radiators often do not get warm ...

How boilers react to violations in the system

• Automated boiler, with a decrease in the flow rate of the coolant in the system, i.e. with cold batteries, or parts of them, it will turn on more often, quickly heat up and turn off. Or it may even show an error - boiling if the coolant stops due to a mud filter, for example.
• A 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 a gravity-fed emergency circulation scheme or replenishment with cold coolant from a tank ... Also, redundant power supply to the pump must be implemented by an uninterruptible switch.

Thus, the primary sign that something is wrong in 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 a decrease in coolant consumption.

Distribution disorders

The cause of 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 booth, a greenhouse ... - are switched on in parallel without equalizing the initial pressure. Need to make a system classical schemes with a hydraulic arrow or with primary-secondary rings.

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

Out of order instruments and automation

Several cases of equipment failure that occur in private homes.

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

• The servomotors for the electrical control of the mixing valves - temperature controllers - do not work.
• Indoor thermostats do not work, weather-dependent automation, there are no control signals for adjusting 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 clogging or airing is not detected and eliminated by primary efforts, consumers turn to specialists, and the issue is gradually resolved ....

Cats on cold batteries do not sleep.

Boiler malfunctions

Common Problems with the operation of heating equipment:

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

If the boiler is working, the radiators are cold, experts recommend, first of all, to assess the technical condition of the main heating element. More specifically, to establish whether the built-in device works . This item is a fixed attribute. modern equipment and is designed to improve its efficiency. Very often, after a long period of inactivity in the summer, the pump may become clogged or covered with a layer of limescale. As a result, it is untimely to remove the heated coolant from the heat exchanger. The boiler is boiling, and the batteries are cold.

It is strictly forbidden to independently repair such complex equipment as a boiler. In this case, either a specialist from the service center is called to the house, or a repairman who has the appropriate certificate or permit.

Experts do not recommend using ordinary, tap water because she is tough. Dissolved salts, when the temperature of the coolant rises, settle on the heat exchanger. As a result, the following problem arises: the boiler is working, and the batteries are slightly 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 an excessive consumption of energy. You can fix the problem by changing the coolant and cleaning the heat exchanger. How to clean the heat exchanger correctly, the video will help you figure it out:

A double-circuit boiler heats water, but does not heat batteries. 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 service mode to DHW and CO mode.

Problems with the heating circuit

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

Failures 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.

The list of the main malfunctions of the heating circuit:

• the filter on the return line or the needle valve (Mayevsky's crane) is clogged;
• insufficient power of the circulation pump;
• the rules for installing a heating circuit with natural circulation are not observed.

Any of the above issues should be resolved before heating season. Otherwise, the room may be left without heat for several days, since the repair involves the complete draining of the coolant.

So, why does the boiler not heat the batteries if everything worked fine over the previous years? The reason is a mud plug, which has formed on the filter of the heating circuit and by itself completely blocks the flow of the coolant. It is solved simply - the water is drained from the pipes or with the help of bypasses its circulation is blocked, the filter is cleaned. To prevent the recurrence of such a situation, it is necessary to make a complete replacement of the coolant with parallel .

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

The second reason why the boiler is working and the batteries are cold is the insufficient power of the circulation pump. The performance of the device is not enough to timely and efficiently pump the entire volume of coolant. Or in the house, the heating system has branches that are at a significant distance from the pump. As a result, the circulation pump overheats, the heating equipment works 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 water circulation, and during the heating season it is often noticed that the boiler is on and the batteries are cold, then the reason lies in the non-compliance with the slope of the main. According to regulatory documentation, only a pipe slope of 10 mm for each running meter in a heating system with natural circulation will ensure the normal movement of the coolant. As a result - uniform heating of the batteries throughout the house. If there is no slope, the coolant stagnates, which negatively affects the temperature of the radiators. You can solve the problem by completely redoing the wiring.

Why are the batteries cold when the boiler is running?

The 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 distribution are clogging of the filter, insufficient power of the circulation pump and lack of slope of the pipes of the circuit with natural water circulation.