How to fix a leak in the cast iron boiler

How to fix a crack in a cast iron boiler

For the repair of heating it is not always possible to use the means of external action. What to do, for example, if it is impossible to find the place of the leak, because the house was made hidden piping and equipped with a heated floor? Do I have to break down walls and open up floors?? No, you will not! In such situations, a relatively new method of eliminating leaks is used. by pouring a liquid sealant for heating pipes into the system. Such sealant is also suitable for heating batteries, when it is not possible to put a clamp on the leak.

The fundamental difference between liquid sealants for heating systems is their ability to fix leaks not by applying to the damaged area from the outside, but directly from the inside.

In an emergency situation it is acceptable to pour into the heating system sealant designed for car radiators

The essence of this method is that the sealant remains liquid in the mixture with the heat transfer fluid and it cures only when in contact with the air penetrating into the system. Gradually hardening, the clots of sealant glue from the inside of the gap in those places where the integrity of the system is compromised.

There are several types of liquid heating sealants available, each adapted to specific applications in particular:

You should not try to look for a universal sealant for the heating system of the house. It is better to buy a specialized composition for the specific parameters of your heating system.

The most famous among consumers are liquid sealants for heating systems, produced by German company BCG. The use of these means are considered the ideal solution for the elimination of hidden coolant leaks. When properly used, the liquid sealant is not dangerous for heating boilers and does not damage the circulating pump and measuring devices.

Sealant for heating pipes and radiators must remain in the system for a long time. Once the sealing agent is added to the heating system, it is possible to forget about the leaks for several years.

Sealants for closed heating systems eliminate the pressure loss caused by leaks in pipes and radiators, but are powerless in cases where the membrane in the expansion tank is broken.

Before you start sealing possible leaks in the heating system, you need to make sure the expansion tank is in good working order

The procedure for using liquid sealants to repair the heating system at home can seem quite complicated. In some cases, clots of sealing fluid cause a partial blockage and prevent the movement of the coolant. Therefore, in order to avoid causing harm to the heating equipment due to his inexperience, it is better to invite a specialist. In any case, you need to study the instructions for use of a particular type of sealant for heating batteries and strictly follow it.

Having made the decision to use liquid sealant to fix a problem in the heating system, you need to make sure that:

  • the cause of the pressure drop is precisely a leakage of the coolant, and not related to the malfunction of the expansion tank;
  • selected type of sealant for heating systems corresponds to the type of coolant in this system;
  • The sealant is suitable for the particular heating boiler.

German BCG-24 liquid sealant is used to eliminate leaks in heating systems

When using liquid pipe and radiator sealant, it is important to maintain the correct concentration. On average, its values are from 1:50 to 1:100, but it is desirable to determine the concentration more accurately, since the effectiveness of eliminating leaks can affect such factors as:

If the volume does not exceed 80 liters, 1 liter of sealant will be enough to pour into the heating system. But how to accurately calculate the volume of water in the system? You need to calculate how many meters of pipes and what diameter was laid in the house, and then enter the data in any of the online calculators. To the resulting volume of pipelines need to add the passport characteristics of the volume of all radiators and boiler.

  • Dismantle or cut off all filters with taps so they do not become clogged with viscous heating system sealant solution;
  • Unscrew the Mayevsky tap from one radiator (the first in the direction of the coolant) and connect the pump (type “Malysh”);
  • Start the heating system and let it warm up for an hour to a temperature of 50-60 ° C at a pressure of at least 1 bar;
  • Open all cocks on the pipes and radiators to allow the sealant to flow freely through them;
  • Remove air from the entire system, including radiators and circulation pump.

You can pour the liquid sealant into the heating system, also with the help of a hand pump for pressure testing

leak, cast, iron, boiler

Drain about 10 liters of hot water from the system into a large bucket, most of which will be used to prepare the sealant solution and a few liters left to flush the pump later;

Sealant solutions for heating systems must be prepared immediately before use, so that the liquid does not come into contact with atmospheric air for too long.

Fill with sealant

Liquid sealant for heating systems must have time to mix with the coolant before it reaches the boiler, so it is advisable to pour it into the supply:

  • Pump liquid sealant solution into the system;
  • Pump the remaining hot water through the pump so that absolutely all of the sealant sludge enters the system;
  • Once again let the air out of the system;
  • Raise the pressure to 1.2-1.5 bar and maintain the work cycle of the system for 7-8 hours with a temperature of 45-60 ° C. This period is necessary for the complete dissolution of the sealant in the heat carrier.

German liquid sealant from BaCoGa Technik.

Today we will talk about independent heating systems, used mostly in summer houses and cottages. Their designs are very different in difficulty, size and cost. They have only one common task. to heat living (sometimes non-residential) rooms independently. The next thing is the differences.

In many cases, systems are closed and use forced circulation of the heat carrier. When heated, the heat carrier becomes wider and the added volume is absorbed by a specialized tank with a rubber bulb inside that compresses to give room for the expanding heat carrier, and after it cools, squeezes the liquid back into the system. And so repeatedly, working in sync with the on-off of the boiler. The system is fully hermetic except for the liquid additive or drain valve and air bleed valves.

The second, more rare, but traditional kind. is an open system. On top, in most cases in the attic of the house, there is an open tank, looking like a flush toilet cistern. That is where the surplus of the heat carrier is pumped up during heating. Such systems are mainly built on the type of gravitational circulation of the heat carrier and do not ask for a specialized circulating pump. The heat carrier is heated in the boiler combustion chamber and, according to the laws of physics, goes up and down through all the batteries and goes back to the boiler for a new portion of heat. True pipes in such a system must be larger to minimally interfere with the circulation.

The traditional system has two major advantages: it is more affordable and it does not stop working (if there is a solid fuel boiler) even when there is nothing in the village! Even if there is only one TAIGA around your house!

Of course, such a system heats the house a little very slowly, in the furnace chamber all the time need to toss up wood or coal. And the closed system, with an automated boiler on any type of energy, makes it possible not to grow a tummy on the couch, even outside the city limits. When it comes to laziness, Russians are unusually resourceful! The most prudent combine the two systems into one. And depending on the circumstances, enjoy the positive qualities of the two systems, switching the heat from one boiler to another. But even such resourceful someday, meet with unfortunate problems, which not everyone can avoid.

  • If the profile pipes, then someday they will come for the monster Rust and will begin to leak. In the meta-twist will rotted linen or cease to be flexible.
  • If plastic pipes, then in the connecting places with connectors at some point leaks appear, as metal fittings and plastic pipes expand when heated at different rates and a tight connection ceases to be such.
  • If plastic pipes and water in them, in your absence it can freeze and tear the pipe. And the crack after that can appear long and quite thin. It is difficult to repair such a thing.
  • If the pipes are copper, then around the corner, too, rust is waiting, cracks appear in the places of soldering, different gaskets in the joints dry up.

People use ethylene glycol and propylene glycol antifreeze. They add corrosion inhibitors and other useful additives Some people get around sharp corners, but such a significant minority is from laziness and from the lack of money and time, and from a variety of other reasons.

An example Every few years the inside walls of pipes and batteries should be cleaned from dirt and deposits that inevitably appear there. Deteriorates the heat output, sometimes to maintain the same temperature begins to require twice as much fuel and cash. Of the thousands of clients we’ve worked with over the past five years, only one decided to wash the system and was shocked by the color of the liquid coming out of the pipe. It’s oil! You can’t tell from the shade.,- he exclaimed.

So, the machinery will start to fail at some point. You can’t change the Russian character. И.

  • Solution If the leaks occurred in a visible area of the pipes, you need to be beckon a good plumber. There are a lot of ways to repair.
  • Solution If the pipes are hidden in the floor or walls, there is no need to call a crew with a thermal imaging camera, no need to break into the house to look for leaks.

The bicycle was invented almost 40 years ago by TM BaCoGa from Germany. It’s a liquid sealant that has to be added to the heat medium.

It is not necessary to stop the process of home heating! The sealant will find the place of the leak itself, it will protrude from the pipe and seal up the hole for good.

For systems with water and gas water heater. BCG 30E For water and boilers with diesel, solid fuel and electricity. BCG 24 For non-freeze glycol or propylene glycol. BCG F For water meter. BCG 84 For system flushing. BCG HR For cracks in sewer pipes and other drains. BCG ABFLUSS For cracks in the concrete pool cup. BCG 10 POOL

How to add BCG to the system?

Remove the dirt filters before completing the repair. The system should be filled with heat carrier. Shake the sealant until the sediment is thoroughly mixed.

Pour BCG into a container with a pump and dilute with water. Connect the system and pump with a hose and clamps. Open the valve and pump sealant into the system.

Close the valve, disconnect and flush out the pump. Turn on the system in normal operating mode. Fix the leak within 1 to 7 days.

Sequence of work

Depending on how serious the failure is, the corrective action depends on. So, if the leak is small, you can do without disconnecting the battery from the circuit, and the repair will require:

  • Place a container under the leak in case of a rupture or a tarpaulin and rag to catch the water.
  • Grind down the crack or rupture with a wire or emery cloth. Not just remove the paint layer, but expose the metal itself.
  • Degrease the prepared place with some kind of solvent.
  • If special glue or epoxy is used to repair the break, strips of thick cloth or bandages will be required. Apply the product to them and wrap several layers around the break.
  • In the case of using cold welding cloth is not needed.
  • A clamp is put on the sealed area and screwed on, but it is important to make sure that its clamps are on the opposite side of the leak. For example, the crack was formed on the inside of the radiator, so the clamps will be on the outside, and vice versa.
  • If the breakage is serious and the hot water spurts from the radiator, you need to call an emergency crew, and not try to stop the leak yourself without having the right tools.

Even the highest quality repair does not guarantee a long life of the device. Refurbished cast iron radiators will still need to be replaced, and the sooner it is done, the safer it will be in the apartment.

Although cast iron radiators are strong and durable, they also leak. Breach of tightness is caused by various reasons:

  • Natural wear and tear. the cast iron body is constantly in contact with water, so it gradually oxidizes and deteriorates. Although cast iron has a high corrosion resistance. only 0.25 mm/year. cast iron radiators rarely last more than 25-35 years.
  • High pressure. especially dangerous its sharp jumps. water hammer. Cast iron can withstand up to 11-12 atmospheres, but strong pressure fluctuations, especially constantly repeated, lead to its destruction.
  • High temperature. For heaters ruinous overheating, arising in heating networks of apartment buildings due to the incorrect operation of heating units. In the normal coolant should be cooled to 80-90 degrees and only then fed into the pipe. But water often comes in too hot or even boils over in a heating plant. It spoils all heat utilities, including radiators.
  • Improperly executed installation. Cast iron batteries are very heavy, one section weight with water up to 7 kg. Radiators tilt if not installed properly. In places of distortions metal fatigue occurs, leading to its destruction. Cracks and fistulas appear.
  • Wear and deformation of seals. plumber’s linen, felt tape, gaskets and seals. Because of this the joints of batteries with pipes, inter-section joints and cocks leak.
  • Freezing of the coolant. occurs when the heating is turned off. Water in pipes increases in volume when turning into ice and breaks the cast iron. Enormous holes in the walls, pipes and shut-off valves deteriorate. Damaged components are almost impossible to repair.
  • Poor quality of coolant. the quality of water in heating systems in MFBs is regulated by RD 24.031.The design documentation for the radiator is in accordance with Order No. 120-91, approved by the Ministry of Heavy Industry. It clearly stipulates the parameters of water supplied to heating systems. Unfortunately, the coolant in apartment buildings very often does not meet the normative data, which leads to damage of radiators.

Causes of damage to the cast iron household boiler and replacement of defective sections

Technology of elimination of damage of cast iron heat exchanger compartments is dictated by its structure. The repair problem is solved by replacing the boiler section. The heat exchanger is a prefabricated structure. Elements are assembled into a single unit by means of accessories (connecting conical nipples). Failure of one of the sections leads to failure of the entire device. What are the causes of destructive deformations and leaks of the heat exchanger?

boiler is leaking can you fix it

A little theory. what phenomena cause the destruction of the heat exchanger?

Cast iron heat exchangers are more durable than their steel counterparts. Cast iron is less likely to corrode in a water environment. That is why gas boilers made of this material hardly rust. However, cast iron (unlike steel) is more sensitive to local temperature peaks. Preservation of physical properties of the structure is negatively affected by the impact of cold water on heated metal.

The listed situations occur when the rules of maintenance are violated:

Clogging of the device leads to overheating of separate small areas of cast iron surface.

Feeding on a working gas boiler with a cold coolant creates a temperature contrast.

Improper adjustment of the burner disturbs the overall thermal regime.

These phenomena lead to the appearance of t.н. “thermal shock” of the metal. As a result, one or more elements become deformed relative to the others, or simply burst.

A common operating breakdown is the instrument leaking. There can be several reasons for this: microcrack in the body of the structure, drying out of sealing compound. Then it is necessary to replace the cast iron boiler section. For repairs it is better to invite specialists from a service organization. Such companies carry out repairs on a regular basis. They have professional tools to assemble the units.

For sealing small holes and cracks in the heating system are used such sealants:

Easy to use and do not cost much. Widely used in construction (window installation, installation of wall coverings and so on).

There are a large number of subtypes polyurethane, polysulfide and others. Not all oligomers are effective for sealing joints in heating systems, so read the instructions before buying.

Cheap, good adhesion to various porous surfaces (wood, concrete, brick, plaster and so on). Easy to handle with sandpaper and other abrasive surfaces. Can be painted and coated with a primer. The main disadvantages are poor water resistance, dependence on ambient temperature, the average mechanical strength after drying and so on.

Therefore, surfaces inside the house are coated with it. Allowed to cover heating pipes with this compound if the temperature inside the system is not very high.

Resistant to mechanical damage after curing. Not in contact with petrol, paints, solvents and other chemically active substances. They are well tolerant to atmospheric precipitations. Optimal temperature range for use from 50 to 80 degrees. Due to its high inertness it is allowed to cover surfaces and pipes that will be in contact with chemically active substances.

Two cans (1 and 10 kg) of Nord-West thiocol sealant. A similar substance is used for heating systems.

The most common type. Are distinguished from others by their low price and relatively high quality. withstand temperature fluctuations in the range from 30 to 60 degrees, well tolerate contact with water and mechanical deformation, as well as contact with chemically active substances.

After curing, to paint in a different color is meaningless, because the paint will come off the cured surface (so put a dye in the composition of this compound). There are many subtypes of silicone sealants, in which various impurities are added to improve the properties of the composition. For example, natural or synthetic fungicides are added to this substance to kill fungus.

Why do cracks appear in the pipeline made of cast iron

When a cast iron pipe begins to leak, you must always determine the cause of the leak. On this basis, a specific repair technique is chosen.

First it is necessary to determine where the crack appeared. Often the leakage is formed in the joints of pipes or from mechanical influences, which caused the appearance of external defects.

External damage can be caused by a variety of reasons:

  • The installation of the sewage pipes was done with mistakes.
  • During the assembly of the pipeline, the manufacturers did not check its tightness.
  • The neighbors connected the ground wire to the riser. Such actions are forbidden by law.
  • Natural wear and tear. Old pipes are useless to fix, they must be replaced immediately.

The crack that appeared at the connection of the fittings, indicates poor work by plumbers when installing the sewage system.

Why the water leaks from the heating boiler

Water leaks from the boiler for several reasons, so before you start repairing it, you should understand what exactly needs to be eliminated:

  • Corrosion. Gas boilers are made of steel or cast iron. These materials are not resistant to the appearance of corrosion, and if you consider that the work of the unit occurs with a constant circulation of water in it, then this cause of failure can be safely recognized as the most common.
  • Failure. A poorly made boiler can leak at welding seams.
  • Burnout of the walls is another common cause of failure. Steel and cast iron can burn only when exposed to open flame. If you operate the boiler following all the recommendations in the manual, this cause of damage is unlikely to occur.

The following factors can lead to malfunction of the gas boiler:

  • Prolonged operation at maximum temperatures;
  • Mismatch of the power of the device of the area of the heated room;
  • Incorrectly set capacity of the burner;
  • Poor quality burner.

Additionally, it should be noted that any boiler is designed for a certain pressure. If the index will be higher than allowed, the device will overheat, which will lead to its expansion and leakage.

The pressure in the heating system must be constantly monitored, because its excessive exceeding the allowable level can provoke an explosion.


Metal corrosion is the real scourge of any plumbing fixture. The heating boiler is no exception. Constant interaction with water is a fertile ground for the development of corrosive processes.

Of course, this does not mean that your boiler will rust very quickly. It all depends on what material his “stuffing” is made of. Ideally, it should be copper or stainless steel. These materials do not rust and do not scale, so they are excellent for the production of such devices.

But the problem is that all their excellent qualities are accompanied by a high cost. Therefore, when choosing water heating equipment, the decision is usually made in favor of boilers, the internal elements of which are made of ordinary steel or cast iron.

Cast iron does not corrode, but it is not often chosen. First, its weight makes it difficult to transport and install the equipment. Secondly, cast iron does not tolerate temperature changes. it can crack, which, by the way, will also lead to leaks. Therefore, for heating heating equipment, this material is not too good.

As for ordinary steel, it has excellent characteristics that are necessary precisely for the heating boiler, and costs inexpensive. But with rust all the time there are problems. Many manufacturers add an anti-corrosion coating to it, but as practice shows, it does not guarantee 100% protection.

leak, cast, iron, boiler

Corrosion is not just a red stain on the walls of the boiler. It gradually destroys the metal. Sooner or later it will definitely lead to the formation of a hole.

A separate factor should be considered the quality of water used in the heating system. Large quantities of air and impurities in it lead to a high corrosive activity. Therefore it is categorically recommended not to use for this purpose ordinary water. for example, river or well water. It is necessary to buy distilled. It gives a little trouble, but believe me, that the constant repair of elements of the heating system will cause much more difficulties.

Feeding the equipment

Many users do not pay attention to this factor, but it has already been proven that it really affects the longevity of the device. It’s the quality of the water. It is believed that “dead water” should be used in the heating system. It contains no oxygen, no additives, no microorganisms. Therefore does not react with metals. If you do add tap water, do so infrequently. Oxygen causes damage to the internal walls of components.

Welding seams

The quality of welds manufacturers must pay increased attention, because the device works under pressure. Abroad, the assembly of equipment has long been working with automation, but we have the seams are made with the help of X-rays. A small screw up will cause a leak. Often it happens at the end of the warranty, when it is difficult to prove a factory defect.

It is possible to seal the crack, weld the seam, but, according to user reviews, such repairs will not help for long.

High pressure in the system

Each boiler is designed for certain parameters of the system, particularly the pressure. Pressure gauges are installed to monitor this indicator. If you see that the pressure is too high, it may indicate some problems in operation.

Burned walls

Although the combustion chamber is made of thick metal, improper use leads to the burnout of steel and cast iron.

  • The boiler works at the maximum mark all the time. High flame bursts out. This may occur due to poor insulation of the dwelling or in case of a wrongly selected model that does not take into account the floor area.
  • Incorrect adjustment of the burner power.
  • Combustion chamber installed too low.

When choosing a technique, study user reviews, the manufacturer. Take into account the volume of the room and install a boiler of suitable capacity, with flame regulation.

What to do if the gas heating boiler leaks

The gas boiler is the main heating appliance of the private house. But sometimes the heating system can malfunction. The main reasons for their appearance is a factory defect or violation of the rules of operation. To know exactly why the gas heating boiler leaks and what to do in this case, you need to familiarize yourself with the main causes of this situation.

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