Chemical cleaning of boiler heat exchangers
Cleaning of the heat exchanger is carried out at the end of the heating season. To carry out the work it is enough to have a standard set of tools. Before beginning of works it is necessary to disconnect a boiler unit from a gas network (main or local) and electricity.
Consider how to clean a floor standing gas boiler :
- The first thing is to dismantle the burner device;
- It is required to disconnect all wires from the gas valve;
- The thermocouple, which is connected to the gas valve by a capillary tube, is removed from the combustion chamber;
- Disconnect the fuel supply pipe;
- Unscrew the bolts or nuts (4 pcs) fixing the plate with a burner, the complete unit is extracted outwards.
To get to the boiler heat exchanger, remove the top cover of the unit, disconnect the draft sensor and chimney, remove the insulation, remove the casing fasteners and the casing itself. After gaining access to the heat exchanger it is necessary to remove the turbulators.
To clean the turbulators a soft metallic brush is suitable, and the heat exchanger itself is freed from soot deposits with a miniature scraper made of thin metal. A brush with a long handle is also used. First clean and sweep the smoke tubes, then remove the soot that has crumbled on the bottom.
Cleaning of the wall mounted boiler is carried out with a toothbrush
Cleaning the Wall Heat Generator. After turning off the gas supply is required to remove the front panel of the boiler. Then the front cover, which covers the combustion chamber, is unscrewed. It is advisable to cover the nozzles with a piece of thick paper to prevent the burner from getting clogged with the soot that falls down. Cleaning the heat exchanger of a two-circuit boiler with your own hands is performed with an old toothbrush or a brush with metal bristles. Once the cleaning is complete, you must clean the heat exchanger with a brush and gently remove the paper with the collected soot. How the procedure is performed, see the video below.
Flushing single-circuit and two-circuit gas boiler
Flushing the heat exchanger of the gas boiler is necessary to remove internal deposits that can disrupt normal circulation of the coolant in the heating system and cause problems with the supply of hot water to the local DHW system. The deposits may also contain substances that destroy metal.
How often you need to perform this action, depends on the type of coolant. If the system circulates purified water, it is enough to do preventive maintenance once every four years, removing deposits. The system with antifreeze should be flushed every two years and the coolant should be changed regularly. under the influence of high temperatures, it eventually changes its properties and can become dangerous for the metal elements of the system.
Causes of scale formation in the boiler and how dangerous it is
The gas boiler, installed one or two heat exchangers (depending on design and functionality), hollow inside, through which the coolant is constantly circulating. Hard water leads to deposits and narrowing of the internal clearance.
To protect the primary heat exchanger, a water treatment and filtration system is installed, which somewhat reduces the degree and intensity of deposits. The secondary circuit or DHW coil to protect against limescale is quite difficult and requires significant material costs.
In practice, in the domestic realities of operation, protection against limescale is used very rarely. Lack of water treatment is the main cause of clogging of heat exchangers.
If the scale is not removed in time, the following consequences will occur:
Gas consumption will increase. the metal used to manufacture heat exchangers, has a good thermal conductivity. Calcium and magnesium deposits, significantly reduce thermal conductivity. To heat the heating circuit and transfer the heat to the water, you will need to burn more gas.The first sign that points to the need to clean the heat exchanger from deposits of salts. the increased fuel consumption. It has been calculated that as little as 1 mm of sediment increases fuel consumption by 10%.
If you do not carry out prompt removal of scale in the heat exchanger of hot water gas heating boiler, you will need expensive repairs. Failure of the DHW coil or heating circuit, this is one of the most common causes of failure of gas water heating equipment.
How to remove hardness salts from water?
It is possible to remove the hardness salts that are harmful to the boiler by means of various filters or water treatment systems.
For the selection of filters, you must first do a chemical analysis of the water, which must necessarily be data:
These are key factors. Water hardness is a scale, iron is a rusty stains on plumbing (sometimes not removed by anything). Dry residue. the amount of suspended solids in the water.
To fight water hardness, it is softened. use filters to soften (desalinate) water. Iron is removed by iron filters, suspended solids are retained by mechanical filters.
Water softening filters work by means of an ion exchange mechanism.
Pictured: Household filters for mechanical purification and iron removal in a holiday home
The composition and capacity of the water treatment plant depends on the initial water quality and the planned volume of consumption. For these calculations, it is best to consult a water treatment specialist.
Basic flushing methods
To begin with, a heat exchanger is primarily a pipe system with fluid moving inside. But the water used in the systems is usually not of high quality. Various metal salts present in it, settle on the walls of the structure, become scale and narrow the passage. There are three methods of scale control:
This article only discusses cleaning with their own hands, and therefore we will not talk about the third method. You definitely can not cope with it alone, as you will need a special compressor that can create a pressure of about 10 atmospheres. Only with the help of this device you can break up deposits on the iron surfaces.
Note! With the other two methods, however, it is quite possible to cope with their own hands. Let’s say right away that it is quite difficult, and the appropriate skills will be needed
If this flushing of the heat exchanger of the gas boiler is used, do not forget that the exchanger itself takes up a lot of space in the heat generator. It is located above the combustion chamber, so it is not easy to get there. The algorithm should be as follows.
Step one. Remove the upper part of the case. To do this, you need to turn off the power and gas supply (if the boiler design provides for this).
Step Two. The exchanger is disconnected from the heating line.
Step Three. The appliance mounts are removed.
After this you can remove the heat exchanger from the heat generator and proceed directly to the flushing procedure. And what you can see after dismantling? As a rule, all the internal cavities are clogged with scale. salts of metals, calcium or sodium, and even trivalent ferum.
For cleaning you will have to use metal tools. pins, scrapers and so on
Be particularly careful not to damage the surfaces of the structure while working
Flushing a Blocked CH Boiler
In some cases, the appliance is soaked in a container filled with a weak solution of hydrochloric acid. And once the scale has softened, you can begin to remove it. At the end of the procedure all internal voids are rinsed with water under slight pressure. You can use a hose connected to the water supply for this purpose.
You can see for yourself how much dirt is released. You need to wait until clean water starts flowing. In addition, you can pound the surface of the device with a mallet (this is a special hammer made of wood or rubber).
Full instructions for flushing a gas boiler
Previously, we told about how to fully flush and clean the gas boiler with your own hands, we advise you to read this information
Let us mention right away that such flushing is a rather complicated procedure. In the course of the work you will need a special device called a booster. And, despite the fact that this option is extremely simplified, for its implementation you should still be aware of a number of important nuances.
What is the simplicity of the method? First of all, there is no need to remove the heat exchanger and dismantle some elements of the gas boiler. It is only necessary to disconnect a pair of pipes (to one of them you need to connect a special hose which will supply a cleaning agent inside the case). After passing through the body, the chemical agent will come out through a second pipe which is also fitted with a hose. Consequently, both in the exchanger and in the booster, the medium will move in a circle.
And now let’s consider what components the booster itself consists of. These include:
- Capacity for the chemical;
- Electric heater (it is not on all models, but people with experience advise to buy such models; so the reagent will be heated, and being warm, it more quickly and qualitatively removes salt and dirt scale);
Note! Such chemical reagents can be all kinds of solutions, which are freely available on the domestic market. And the question of choosing the right reagent is the most relevant
In each case, not only the degree of clogging, but also the type of clogging and the material used in the construction of the heat exchanger must be taken into account.
Next we will find out what means can be used to flush the heat exchanger of a gas boiler.
Previously we talked about how to choose a good stove with a heat exchanger for the bath, we advise you to read this information
With what, how to remove limescale from the heat exchanger
For descaling at home I recommend to use 20% citric acid solution (250 g/litre) as a descaling liquid.
You can also use commercially available special compositions for the removal of scale in household washing machines and dishwashers. Read the labels on the packaging carefully. The chemical should be designed to remove scale, not to soften water (not to prevent deposits).
Less available, but if you want you can find and buy special compositions (liquid or powder) for professional cleaning of heat exchangers from scale. The choice of such chemicals should be approached with caution. A wide variety of potent chemicals are available for cleaning different types of equipment. You can buy the chemical, which will cause corrosion of metal or protective coating of the heat exchanger.
Particular attention should be paid to the choice of cleaner for the heat exchanger without removing it from the boiler. The chemical composition chosen must not damage not only the metal of the heat exchanger, but also parts of the boiler made of other metals, as well as rubber and plastic parts.
In order not to err in choice I recommend to use the chemical agent, which is relatively chemically weaker and, therefore, safe, time-proven, accessible and cheap, i.e. food or technical citric acid (250 g/liter).
If you do not accumulate deposits, you can even use common toilet bowl treatment products that contain acid, such as oxalic acid, to regularly clean the heat exchanger from scale.
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A little bit of theory
The principle of operation of any gas boiler is to heat the coolant during combustion of gas. The design of the heat exchanger, through which the coolant heated to a certain temperature moves, is approximately the same. This is a curved tube made of copper or stainless steel, which is called a coil. When the gas is converted into thermal energy, it is heated and the water or any other coolant that circulates in the heating system is heated.
For heating water in the heat exchanger is responsible for a system of plates, which is externally identical to the car radiator. With its help, you can increase the temperature of water, reduce its or send it to one of the circuits in the case of two-circuit boilers.
It is this, conditionally speaking, the “radiator” of the gas boiler and needs regular cleaning, or rather, flushing.
How to clean
Many ordinary people who have decided to perform a heat exchanger flushing with their own hands, as a rule, are asked two questions. How to clean this appliance? What to clean it with? To begin with, let’s tell you what chemicals are used to flush the heat exchanger.
The modern market of household chemicals is very well saturated with all sorts of means for cleaning the gas boiler.
Therefore, it is necessary to be very careful with the choice of substances for flushing. First of all, you need to consider the following factors:
At home it is most appropriate to use the following chemicals to flush this element of the boiler:
- Citric acid, which is quite effective in removing limescale;
- Sulfamic and adipic acids are practical for regular flushing of the heat exchanger, when the contamination is not so significant;
- Hydrochloric acid is designed to remove a fairly strong scale, but when using it, you should consider the properties of the material of the heat exchanger;
- water-soluble gels, which are not as aggressive as acidic reagents, but are no less effective.
The important point: it is necessary to observe all safety precautions when working with chemical reagents.
Types of flushing
To clean with your own hands this structural element of the boiler from the scale, it is optimal to use the following two methods:
The essence of the mechanical method is as follows:
- The gas boiler is disconnected from the gas supply and power supply;
- The heat exchanger is disconnected from all lines and carefully withdrawn;
- The device for 3-7 hours (depending on the degree of contamination) is soaked in a container with an acid solution of small concentration;
- Thoroughly rinse the heat exchanger with tap water and re-install it.
Specialist advice: when flushing with running water, the appliance can be simultaneously tapped gently with a mallet to increase the cleaning effect.
The chemical method is characterized by the fact that to flush this element of the gas boiler does not require its dismantling. Cleaning in this case is done with the help of special equipment for flushing, which is called a booster. This device allows autonomous circulation of the reagent in the heat exchanger. (An informative article on chemical boiler flushing can be found here ).
The procedure is as follows
- disconnect the two pipes of the device from the common boiler system;
- one of them is connected to the booster hose, through which the flushing liquid will be supplied;
- To the second branch pipe also connect the hose, from which the reagent will flow to the booster. so the flushing agent will circulate between the heat exchanger and the booster;
- After cleaning, the spent chemical solution is drained and then rinsed well with water.
Note from the specialist: for successful cleaning of the heat exchanger from scale with the booster, flushing should be carried out several times.
And we would like to point out that we did indicate two effective ways to clean the gas boiler from contamination. We hope that our recommendations will help you to perform at home flushing of the heat exchanger with your own hands.
Watch the video, in which an experienced user clearly explains the peculiarities of flushing the heat exchanger of a gas boiler:
How to clean a gas boiler: procedure for each node and video cleaning with your own hands
Flushing a heating boiler from scaling: peculiarities of the procedure and a video of doing it with your own hands
Replacing a gas boiler in a private home: documents, rules and procedure
How often you need to clean the heat exchanger?
When visiting thematic sites there is very contradictory information regarding how often you should clean the heat exchanger, and all other elements of the heater. As a rule, information about the intervals between maintenance is specified in the manufacturer’s instructions for a particular model. But it should be remembered that the above information is approximate and implies the fact that the operation will be carried out in the most favorable conditions. In fact, flushing the heat exchanger of the gas boiler is often required more often.
There are indirect signs, by which it is possible to determine the degree of clogging of the heat exchanger. It is these that accompany the operation of the heater.
- Fuel consumption increases markedly. Statistically, in the case of internal scaling on the surface of the heating element, the fuel consumption can increase by up to 15.
- The load on the circulation pump increases, it makes background noise, there are pauses in its operation. All these points indicate that flushing is required.
- The performance of the heating system has dropped. The radiators are taking longer to heat up, the temperature of the operatingliquid in the return pipe is low and the burner is always on. All of these signs also clearly indicate that it’s time to start flushing.
- Weak pressure in the faucet and a “barely alive” fluid in the hot water supply also tells you that there is definitely a problem in the heat exchanger.
Please note! Modern gas boilers are made with the expectation of long-term operation, and spare parts to them are quite expensive. For this reason, cleaning should begin immediately upon detection of the signs described above, otherwise the maintenance costs of the device will increase significantly.
Proper operation of the heat exchanger: What to do to ensure that the device serves as long as possible?
- First of all, the make-up valve must be positioned correctly. During repair work, the liquid can flow out of the system. It is often necessary to make up the water by means of a special tap. If it happened once, it is not a big deal, but if this tap is located at the entrance to the heater and provided with cold water, then as a result the cast iron can experience a so-called “thermal shock” and simply crack. This happens because of the fact that the heated heat generator is fed cold liquid and the temperature jumps locally, and cast iron, as you know, does not like this.
- Do not fill the system with antifreeze, in a pinch, only use brand-name tool. It costs, by the way, about 600 per liter. And if the area of the house is, for example, 250 square meters, then we need about 200 liters of antifreeze. Of course, if you want it can be diluted with water, but subject to strict compliance with the proportions. For example, to obtain a liquid that will freeze at minus 25 degrees, the proportions are 1:1. Simply put, for the mentioned area you will need about 100 liters (read: 6 thousand). Expensive. of course, but with such a coolant you will be able to protect yourself from possible problems for several years.
- Pour softened water into the system. As we have already found out, in this matter, the hardness of water plays a key role. If the coolant is hard, it will contain metal salts that can accumulate on the walls of overheated heat exchangers. It’s almost like the scale that builds up in the kettle.
So, we found that flushing the coil gas boiler (regardless of the method chosen) takes a few hours and requires certain skills and knowledge. This can be done by your own hands, or you can trust a specialized firms. And to check how well the cleaning was carried out, you can both by indirect signs (increased productivity, absence of extraneous noise and overheating), and by means of a video probe inserted into the boiler drum after the flushing. This will visually verify the quality of the result. The mentioned firms, by the way, provide such service.
Clogged DHW circuit In the dual circuit heat exchanger from the boiler SF The heating circuit has been flushed with a toilet duck and gvs no flow is very small but about 3 liters per minute should be 17l/min, I think to X-ray to see the insides and find the best end to cut, to follow the mechanical cleaning.
1.Take off the hot water heat exchanger 2.try fine steel.wire to determine where the clog on both sides (cork-sediment) heat exchanger, usually in the elbow at the outlet 3.There is a cheap cable for cleaning pipes, 1 meter in stores fix price 4. I got a clog in the second knee of the heat exchanger, and the inputs are inclined and clean (push through) the cable does not work t.к. turning knees 180 degrees, then I did so-I at the second knee at the end( t.к. ends are not over the burner) drilled a hole and clogged the metal. pin, then soldered tin.It works and you may need it for future problems.Rinse preferably at least once a season and put a filter on the return