Safety of solid fuel boilers. Why do boilers explode?

When purchasing a solid fuel boiler, in the future, during installation and operation, we usually rely on the recommendations and instructions given by the manufacturer. Other rules and regulations regarding the operation of such equipment, people most often do not know. The exception is houses in a dacha cooperative, where a number of special requirements may exist. However, in reality, most often it turns out that a person is not aware of the full degree of risk, like someone who holds a weapon in his hands, not knowing how to use it. Therefore, first of all, it is necessary to foresee all the dangers that are possible during the work of this type heating system, as well as those measures that will help to significantly reduce the threat.

First of all, this is a fire hazard, the causes of which can be:

• Violation of the rules for installing a chimney. If the chimney is assembled from materials that are not designed for temperatures that can reach 300-500 ° C inside the pipe itself, this naturally leads to severe overheating, passing through the ceiling without thermal insulation, and from contact with lumber, a fire occurs in a matter of minutes .
• Chimney malfunctions. If during the installation of the chimney there is such a strong back draft that, when opening the door of the loading compartment, we see a fire flashing like a torch, there is a risk of getting a fire soon - in such cases, the ceiling above the boiler lights up.
• If the boiler itself is installed incorrectly. Plants that manufacture equipment usually recommend that the boiler be placed on a steel sheet or concrete pedestal. No objects made of flammable materials should be located near the boiler - at a distance of less than 0.9 m from the sides of the boiler, and in front of it, i.e. from the loading side, at a distance of at least 1.5 m. A heat-reflecting screen must be fixed on the wall behind the boiler, in proportion to the dimensions of the boiler itself. It must always be remembered that, despite the thermal insulation of the boiler, side walls it is heated up to 90-100 o C even during the most normal operation, the front, loading wall can reach an even higher temperature - normally up to 130 o C.

The second danger is the risk of the boiler exploding.

And in this case, the cause is the strongest overheating, to which the following factors lead:

• If the heating system is not assembled according to the rules– for example, there is no safety valve, safety group, and expansion tank closed, then circulation pump won't save the day. And the point is not only in the electrical dependence of the system, but in the fact that at the first power outage and the pump stops, the circulation stops, the pressure increases, and the coolant does not flow to its destination. The weakest part of the heating system is not pipes, radiators or taps, which most often withstand at least up to 10 atm, but the cast-iron boiler itself holds a maximum of 3-4 atm, and steel even less, 1.2 -2 atm. Consider that you are lucky if there is almost no firewood left in the boiler and you haven’t had time to add more - it means that the temperature will steadily fall. Otherwise, a person has no more than 10 minutes before the explosion - for evacuation. An attempt to put out the fire can turn into a fatal mistake - only a suicide will think of splashing a bucket of water or closing the blower from below, trying to drown out the boiler. As a result of the explosion of a cast-iron boiler, doors can fly out and corners of the house disperse, and steel ones are not much safer in this regard.
• Boiler selected incorrectly. The most common misconception is to choose a boiler with the largest firebox according to the principle “the more the better”. A person is too lazy to cut and throw firewood once again and he insistently demands a boiler with a firebox half a meter in size, not realizing that such fireboxes are intended for an area of ​​​​about 300 m 2, and not for its 40-50 m 2. Thus, overheating is 100% guaranteed - and there are very good chances to “start into space”, just 5 pieces of lining and half an hour will suffice.
• The pipe at the outlet of the boiler is very narrow and an open expansion tank is not installed. A situation familiar to many is that all batteries are cold, despite the fact that the boiler itself is boiling. The narrow diameter of the outlet pipe, and consequently, a very weak, slow outflow of heat through the system, and a closed expansion tank can lead to the most disastrous results, up to the boiler explosion.
• If the number of radiators does not match the boiler capacity. For example, in those cases when, having acquired a more powerful boiler, people leave the batteries of the old system, planning to heat the extension in the foreseeable future and buy additional required amount radiators, and then forget to do it. As a result, the boiler heats a smaller area than the one for which it is designed, and therefore it boils (for example, if a 16 kW boiler, provided for 120 sq.m, actually works 60 sq.m, although such an area requires a boiler no more than 10 kW.

The pipes of the heating system are destroyed due to overheating.

Regardless of the type and power of the boiler, if pipes containing PEX (metal-plastic, polypropylene and some others) are used directly at the outlet of the boiler, they may not withstand high temperatures(more than 90 ° C) even within half an hour - delamination, deformation, melting begins. A coolant will flow from a damaged pipe - strong water vapor, or toxic antifreeze (ethylene glycol). The circulation and removal of heat from the boiler is disturbed, and, as a result, the boiler may explode.

Be aware of all these risks and observe the following requirements safe operation boiler equipment:

1. When buying a boiler, we focus strictly on the power that is necessary for the complete selection of heat for heating real, and not planned for the future areas.
2. The place under the boiler must be specially prepared, with maximum thermal insulation - reflective screens must be installed, under the boiler there must be a pedestal made of stone or concrete, steel sheet, etc.
3. For the chimney, its inner part, it is better to choose “sandwich” pipes and insulate them, and make pipe passages through the ceilings using special standard elements.
4. The number of radiators must be selected taking into account the power of the boiler or otherwise take heat from the system.
5. As pipes coming out of the boiler, or “strapping”, choose steel, which can become a kind of buffer for heat removal. PEX-containing pipes, for example, polypropylene, with a strictly required diameter, can only be connected after 1.5-3 m.
6. Prefer expansion tank open type and install it in the system as high as possible. In case of choosing an expansion tank closed type take care to equip it with a safety valve that will operate at a lower pressure than that which is working for the selected boiler. When adjusting the expansion tank when starting the system, you need to ensure that the factory air injection in it coincides with the operating pressure of the system.
7. Do not place all hopes on the circulation pump and insure yourself with a gravity-flow system or at least connect 2-3 batteries by gravity. Or purchase a generator for uninterrupted operation of the pump. These measures are necessary to prevent overheating of the boiler during a power outage.
8. Consider the individual characteristics, features of your boiler.
9. Don't be overconfident and keep your heating system under control, remembering that the system may not always work the way you intended. Be sure to follow all the above precautions, which are derived from the real experience of the owners of solid fuel boilers. Let's learn from others' mistakes!

2017-06-23 Evgeny Fomenko

Causes of boiler overheating

There are many different reasons why this can happen, let's try to consider them using examples of boilers with different ways work.

Gas

The first reason why a gas boiler overheats and the liquid boils in it is the lack of circulation in the heating circuit. The reason for this lies in the clogging of the filters, or the heating circuit has been aired. It is necessary to inspect all filters, wash them, and, if necessary, replace them with new ones. If the problem lies in airing, it is necessary to remove the air. Very often this situation occurs in old gas appliances firm Navien.

The next reason can be a banal clogging with scale, that is, particles of plaque have exfoliated and clogged the duct. At the same time, clicks may occur during operation, or such sounds as if it is knocking. The solution is quite simple - you need to clean the device using special chemicals, or using acids.

It is also possible that the system was not used for a long time, and then it was started without a preliminary run. ventilation system. During startup, noise sounds are possible, and the device gives an error about insufficient circulation. This can be caused by sticking in the pump due to downtime. It is necessary to disassemble the pump and rinse, then restart the start again.

A poor-quality gas-air mixture can cause an explosion, there are lower and upper limits at which an explosion occurs.

Another reason is non-compliance with the recommendations for the installation site of the equipment. If the room has high humidity air or low temperature, the metal from which the boiler is made will deteriorate. Corrosion may occur if sulphurous fuels are used.

After all, there are such areas that it is not possible to clean completely with the help of blowing, for example, the gaps of pipes and partitions. If the boiler is constantly in working condition, moisture cannot damage it, and when it is turned off, the ash, as well as the lining surface, absorb moisture, which then leads to corrosion, and this in turn can lead to gas leakage and explosion.

Often users have a question why water gurgles, there may be several reasons. The first is that the pump is out of order or wedged, the coolant boils and similar sounds are heard. Second, the battery is clogged.

If your device overheats, follow these steps to fix it:

Solid fuel

Very often abnormal work solid fuel boiler heating is associated with wrong choice models. That is, when choosing a wood-burning boiler, the user prefers a device that has a large firebox, which is designed to heat an area over 150 m2.

However, if you have a heated room of only 70m2, this will cause the device to overheat. And also to an increase in pressure in the boiler, which can ultimately lead to an explosion. Another reason may be an incorrect installation, because often such a responsible matter is not entrusted to qualified specialists, but to people from the street.

The next situation that can increase pressure is if the electricity suddenly turns off, and as a result of this, the circulation pump stops. The coolant stops circulating through the heating system, the pressure rises sharply, and the liquid begins to boil quickly, all this can lead to an accident.

Circulation pump in the heating system

What to do if this happened? Shut off the fuel supply to the combustion chamber, it is strictly forbidden to extinguish the flame with water, as this can lead to a thermal burn of the skin and an explosion of the boiler. To safely extinguish the flame, you can use sand, ash.

Steam

Consider what are the main reasons why a boiler can explode. If the level of liquid in the steam boiler is sharply reduced. This reason is the most common, due to a decrease in liquid, the walls overheat above the maximum allowable value. There is a change in the chemical structure of the metal, its resistance decreases, and when pressure is applied to the walls, they are amenable to blowing, which ultimately leads to an explosion.

When the water level drops, in no case should it be filled cold water, this will lead to a coma, that the metal will lose its ductility, its fragility will increase and cracks will form. If a decrease in water is found, it is necessary to gradually turn off the device, stop the fuel supply. After it cools down, fill it with liquid until established norm, then start again.

To prevent the liquid level from dropping to a critical value, it must be equipped with a device that controls the upper and lower limits of the liquid level, and if a mismatch is detected, stop the fuel supply.

Fluid of inadequate quality. Occurs as a result of a change chemical composition water, and most often, an increase in its hardness, since the deposition of scale increases. If the water that flows in your pipeline does not meet the specifications stated in the instructions, you need to clean it.

For this, a soda-lime solution is used, sodium, phosphate precipitation, it can also be purified by cationization, this method involves filtering water through a special cation material.

The formation of scale on internal elements, which is formed as a result of the accumulation of salts contained in the feed fluid. This can be avoided by using cleaning filters that are installed before entering the device. If it has already accumulated, it is necessary to clean the boiler in order to avoid overheating it. The scale layer should not exceed 0.5 mm for the correct operation of the device.

The accumulation of explosive gas in the combustion chamber, which occurs due to improper operation of the ventilation system, or fuel supply.

Often the cause of device explosions is defects or malfunctions of the main units, a decrease in their safety margin, due to improper operation, breakdown of control sensors, as well as measuring devices.

Increase in working pressure. The main reason for such a malfunction is the failure of the safety elements, as well as non-compliance with the set mode.

Heating boiler safety group

In order to timely identify a malfunction, it is necessary to periodically subject them to technical certification(once a year), as well as tests, for greater safety, conduct them not only according to plan.

Electrical

Causes of overheating in electric boilers:

Precautions and Prevention of Overheating

To preventive and non-admission measures emergencies may include the following:

• Install an additional circuit for cooling a boiler that runs on solid fuel. In a double-circuit boiler, with an increase in the coolant, the liquid can be cooled due to the water supply system.
• Installation buffer tank , it will prevent the boiler from boiling, take on excess temperature, and can also store heat for the heating circuit.
• Install an uninterruptible power supply. If there is a power outage, the UPS will automatically turn on, the energy will come from the battery, and the system will continue to work.
• Periodically clean the ventilation system.

The principle of operation of the heating system

To describe very briefly, then the principle of the heating system in a private house is that a certain liquid, whether it be water or frequently used antifreeze, is heated in the boiler to the temperature set by the user.

Heating system diagram

Then it flows through the heating main (pipe) to the radiators, in which it gives off its heat, then circulates back through the return circuit to heating device. There it warms up again, it is essentially a closed circuit.

There are two types of system:

• Single pipe. It is the most economical and easiest to implement. It has the form of a ring in which heating radiators are sequentially mounted. The coolant circulates in a circle, while the most heated liquid enters the first radiator, which shares heat with it and at the same time loses several degrees, while the already significantly cooled coolant reaches the fifth or sixth radiator.

  The way out of this situation, so that the batteries are not cold, is to increase the number of sections with each subsequent radiator, so that heat losses are not so noticeable. Or increase the temperature of the coolant in the boiler, and this will entail significant costs.

  However, it is possible to install a circulation pump, which will artificially increase the speed of the coolant and, accordingly, reduce heat loss, and this will also slightly reduce the heating interval. However, there is a drawback here, namely, the cost of electricity.

• Two-pipe, many times superior in energy performance. It involves branching the coolant into two outlets, as a result, heat losses are halved. They have a reverse circuit.

  However, to build such a system, you will need twice as many pipes, shutoff valves, sensors. Most often used in gasified premises.

Since ancient times, the stove has been the main source of domestic heat. One of the modern and effective means creating heat in the room today are heating devices for water heating systems. They are mainly used in cottages and mansions for heating houses with large area. They are especially intensively exploited during the onset of frost. And this, in turn, leads to an increase in the number of fires in this period. So, only in January 2016 in the territory of the Yurginsky district there were 2 cases of explosion of heating boilers. This suggests that it is necessary to remember about safety measures, rules for using and caring for heating devices.
First of all, the state of the apparatus must be constantly monitored. It is necessary to clean the ash chamber in a timely manner. Attention should be paid to valves smoke channels: they must be opened before starting the fire. Do not use the heating device for cooking purposes. There are other heat sources for this.
The following malfunctions can lead to a boiler explosion and subsequent fire:
1. Lack of water leading to overheating of the boiler walls.
If there is not enough water in the boiler, the walls overheat, since the heat of hot gases, designed for heating and evaporating water, is not removed. The desire to replenish the lost water in the boiler by immediately supplying it only accelerates the explosion of the boiler, since the water, falling on the overheated walls, instantly evaporates and a pressure exceeding the calculated one arises in the boiler.
2. Excess allowable pressure in the boiler. This is possible due to the formation of an air lock in the heating system or freezing of water in one of the sections of the system.
3. Deposition of scale, causing burnout of the walls. The deposition of water scale on the inner walls of the boiler and due to its untimely cleaning leads to overheating of the boiler walls and a decrease in its strength.
4. Corrosion of the metal of the walls and seams. As a result of corrosion mechanical strength the metal of the boiler walls is reduced, and bulges are formed. With a further increase in pressure in the boiler, cracks appear in places of bulges, and the boiler explodes.
In addition, explosions are possible as a result of defects in the metal, welding and riveting seams, changes in the structure of the metal of the walls during operation (temperature changes, chemical effects of water and steam), violations of the strength of the metal due to improper boiler manufacturing technology.
To ensure normal operating conditions, heating devices are equipped with safety devices, fittings, automation devices, safety valves, water level indicators, pressure gauges, thermometers.
To prevent the heating device from causing a tragedy, do not forget to follow the safety rules!
Take care of yourself and your loved ones!

Any gas equipment carries a potential hazard. Can it explode geyser? For some reason, many users believe that the operation of a boiler or column is much more dangerous than, for example, gas stove. Is it so? Under normal conditions, there will be no explosion, but improper installation or breakdowns can increase this probability.

For what reasons does technology explode, how to avoid such a fate? Let's consider in detail.

Experts list the main reasons for such consequences:

• Self connection. Note that is allowed. You can hang the device, bring a water pipeline to it. But you must entrust the connection to the gas main to a professional. First you need to collect. Then you turn to gas service, which will come to the call and connect the device. Only then can the column be put into operation.
• Soviet geyser. Why is it dangerous? Outdated equipment does not have a protection system. This includes control sensors, thermostats that monitor the operation of each node. In the event of overheating or fuel leakage, the old apparatus will not respond.

It has been proven that an explosion occurs at a concentration of gas in the air up to 5–15%.

• Unauthorized changes in the design of equipment. It is forbidden to change anything in the speaker device yourself. If the work is disrupted, not only a breakdown, but also an explosion is quite possible.

Can a modern gas boiler / column explode

Theoretically, for the technique to explode, the following reasons are necessary:

• An empty pipe is heated without heat carrier.
• The water in the radiator does not circulate, but stands and boils to critical temperatures.

Both that, and another is impossible because even in the cheapest columns of "Economy class" the security system is installed. Empty pipes will not heat up, because until you open the mixer to supply water, the burner will not start. And as soon as you close it, the heating will stop.

Heating temperature, liquid flow rate are controlled by special sensors. All models are equipped with these sensors:

• Thermal sensor. Monitors temperature rise. As soon as the water heats up to the set value, it gives a signal to the main module and it turns off the heating.

• flow sensor. Fixes the speed of pressure in the pipes.
• Flexible diaphragm. Serves to open the gas valve. If the pressure in the line is sufficient, then the membrane is bent and the fuel enters the burner. As soon as the pressure decreases, the membrane returns to its original position and the gas supply stops.
• Ionization sensor. If the flame in the burner goes out, the sensor gives a signal to turn off the equipment.
• Removal product sensor. Reacts to the lack of draft in the chimney. Ideally, the smoke should exit normally through the smoke shaft. If this does not happen, protection is triggered. Did you hear that it smells like burning? Then check the chimney. In case of blockage, the mine is cleaned.

Smell of gas from the boiler in the house? overlap shut-off valves and call the gas service to check.

Danger arises when technology gets out of control. What experts recommend doing to avoid accidents:

• Buy heating equipment only in specialized stores. Get a warranty so that in the event of a breakdown, contact the service center.
• Trust the connection to specialists.
• Perform preventive maintenance once a year Maintenance. Clean components and parts from scale, soot and blockages.
• If problems are observed during ignition (the column bangs, claps), be sure to contact the master.

Any technique can be dangerous if used incorrectly. Control the operation of your devices, then you do not have to deal with the consequences.

Steam boiler explosion December 6th, 2015

At the dawn of the era of steam power, boiler explosions were a very common occurrence. This was due, first of all, to the insufficient level of knowledge in the field of thermodynamics and strength of materials, as well as poor quality materials used for the manufacture of the first boilers and the primitive technology of their production. By the beginning of the 19th century, a sufficient level of knowledge in the field of design and operation of steam boilers had been accumulated, and explosions of stationary boiler plants became rare.

Here's what it looked like...

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In the 19th century, boiler explosions were typical mainly for steam locomotives, since their boilers are made of lightweight construction and at the same time are highly boosted, and, in addition, they also experience shock loads when moving along rails. In addition to everything, the locomotive boiler is a fire-tube boiler, where steam pressure acts on outer surface heat exchanger pipes, which also reduces strength. It is for this reason that in late XIX centuries, strict standards for the design, maintenance and repair of locomotive boilers were developed and adopted. The designs of stationary and ship boilers have a much greater margin of safety and explode much less often than locomotive ones. Officially, the very first boiler explosion on a steam locomotive occurred back in 1813, when engineer Brunton, demonstrating his Mechanical Traveler, decided to increase its speed by further increasing the steam pressure in the boiler, but the boiler unexpectedly exploded, killing 15 people.

Photo 4.

There was no cardinal way to deal with this phenomenon, which usually occurs solely due to the "human factor".

Driving a steam locomotive is not easy. With the help of water gauge glasses, the driver must monitor the water level in the boiler, avoiding a strong increase or decrease in the level. Depending on the mode, the steam consumption is different and it is necessary to increase or decrease the water supply to the boiler.

Photo 5.

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If for some reason the driver missed the level, he must supply water very carefully. If you open the injectors to failure, jets of water will rush into an overheated boiler with red-hot, red-hot walls and pipes, it immediately forms too a large number of pair, and in some cases performance safety valve may not be enough - the pressure of the resulting steam will simply break the boiler. Sometimes this happened, but the driver who violated the instructions rarely had the opportunity to tell someone about his mistake ...

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