How much citric acid to flush boilers

Flushing the coil of the gas boiler with citric acid

The article is devoted to an important problem faced daily by millions of owners of boilers. Learn how to flush a gas boiler heat exchanger with your own hands in minutes and for free. But remember, if you’re not sure don’t try it, a gas boiler is not a test field, there’s a risk of explosion.

A solution of citric acid at 60°C perfectly removes scale and oxidation without affecting the metal of the heat exchanger. This product is perfectly suitable for cleaning copper, brass and stainless steel devices. Depending on the degree of contamination, the recommended concentration is 0.5 to 1.5%.

Gas water heater. the principle of operation, the causes of clogging

Flow-through gas water heater is essentially a heat exchange device. Its main element is a special pipe circuit. The water stream flows through it and is heated by the open external flame of a gas burner. Modern models are turned on automatically. as soon as the mixer valve is opened, the ignition and transmission of thermal energy to the circuit walls, and from them to the stream. As a result, at the outlet the user receives hot water.

Despite the simplicity of design and scheme of action, in the work of such an appliance is constantly formed harmful interfering factors. above all, this:

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  • Fouling. on the outer walls of the heat exchange circuit. Worsens heat transfer from the burner to the water, reduces efficiency, leading to increased fuel consumption.
  • Scale. builds up on the inner walls of the heat exchanger. Formed as a result of decomposition of salts dissolved in water and solid insoluble precipitation. Reduces the flow, reduces the pressure, degrades the performance.
  • Soot. solid products of gas combustion inevitably settle on the burner and igniter itself. Flame periodically extinguishes, the intensity of combustion decreases, productivity deteriorates, and there is a risk of gas leakage.

In addition, depending on the water quality in the heating appliance may be deposited other impurities. rust, silt, sand, etc. To eliminate their influence, you need a periodic and timely competent cleaning of the gas boiler.

How often is the flushing required?

Many popular manufacturers of gas boilers such as Navien, Baxi, Ariston, Vaillant in the instruction manual indicate the frequency of flushing the heat exchanger. But the actual operating conditions often make their own adjustments. The practice of connecting gas boilers to the heating system with hard water shows that the heat exchanger should be flushed every season. To avoid encountering this problem in the middle of a cold winter, we recommend flushing immediately after or before the heating season. Below are some typical signs that your gas boiler heat exchanger needs to be cleaned:

Increased gas consumption

Lime scale reduces the thermal conductivity of the heat exchanger, thereby forcing the gas boiler to burn more fuel to reach a set temperature.

Constantly switched on burner

Increased operating time of the burner can also indicate the presence of scale preventing normal heating of the coolant.

Rumble and intermittent operation of the circulation pump

Reduction of the effective diameter of the heat exchanger channels, makes it difficult for the circulation pump to pump the coolant. Its operation in the limit mode can be accompanied by a hum and malfunctions.

Decreased head in the DHW circuit

An indication of the presence of a layer of scale in the secondary circuit of a two-circuit boiler can be a decrease in the head of the hot water line.

If one or more of the above symptoms are observed in the work of your gas boiler, you need to urgently flush, in order to avoid breakage of expensive components of the heating system and high costs for their repair or replacement.

Where is it and how to remove it

The basic methods involve completely removing the heat exchanger from the boiler. Cleaning without disassembly and extraction is possible only with the hydrodynamic flushing method, carried out exclusively by specialists. Nevertheless, the process of extraction does not require special skills and special equipment, and the device of all models of gas boilers does not differ dramatically.

Location of the heat exchanger in the example of wall-mounted Baxi LUNA-3 Comfort 240 Fi.

  • The first thing is always to remove the front cover, just unscrew the bolts and gently remove it.
  • Drain water from the boiler through the appropriate outlet valve (usually located inside the boiler), be sure to bleed pressure if available.
  • Next, you must remove the front cover of the combustion chamber. In simple models it is immediately visible, in more complex models the combustion chamber can be insulated with fire, heat or noise insulation material, rubber seals. You may also need to remove the upper part of the combustion chamber.
  • Usually there are temperature sensors or water flow sensors on the tubes of the heat exchanger which must be disconnected.
  • It remains to remove the fasteners, clamps, disconnect pipes and remove the heat exchanger. Be careful, because when you disconnect the heat exchanger may spill residual water, cover the electronic elements and wiring under the combustion chamber.

In floor standing gas boilers with an open combustion chamber, the process is even easier because the heat exchanger is available immediately after removing the lid of the case. In general, you can learn the device of your boiler model from the images of the instruction manual, for many models there are clear examples of disassembly on YouTube.

How much does it cost to flush the exchanger of the gas boiler?

Types of work Unit. dimension. Price,
Onsite DHW (hot water) heat exchanger flushing pcs from 4500
Flush the main heat exchanger of the wall mounted boiler (traditional) at the service center pcs from 3000
On-site cleaning of the main heat exchanger of a wall boiler (traditional) pc from 5,500
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Diluted hydrochloric acid does not react with copper under normal conditions. only in the presence of high concentrations of oxygen, so you can safely flush copper heat exchangers of wall mounted gas boilers (or cleaning of heat exchangers containing copper alloys) with hydrochloric acid.

Heat Exchanger Flushing Fluids

Regardless of the cleaning method you choose, you will need a flushing reagent. Choose the flushing fluid wisely, as some of them can damage and even destroy the heat exchanger of your gas boiler. Let’s consider in which cases one or another solution is suitable:

Hydrochloric acid

An aqueous hydrochloric acid solution with a concentration of 2-5% is successfully used for cleaning copper or stainless steel heat exchangers. Special additives. inhibitors. help to protect the metal without preventing the dissolution of oxides and carbonates. Hydrochloric acid cleaning is the privilege of professionals who are aware of their actions when dealing with this aggressive reagent. By yourself, at home, to clean the heat exchanger of the gas boiler with this agent without a clear understanding of the processes involved is not recommended.

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Sulfamic acid

Sulfamic acid heat exchanger cleaning is especially effective for removing metal oxide deposits. This cleaning agent is safe for all materials and can be successfully used at home. Composition for flushing of the heat exchanger includes 2-3% aqueous solution of sulfamic acid and corrosion inhibitors.

Picture 5: Plate heat exchanger flushing

Phosphoric acid

Washing by phosphoric acid is effective for all types of gas boilers heat exchangers. This detergent not only removes limescale and dirt perfectly, but also does no harm to the metal and even forms a protective film. To obtain an effective reagent, you need to dilute orthophosphoric acid in water to obtain a 13% solution.

Citric acid

A solution of citric acid at 60°C perfectly removes limescale and oxidation without harming the metal of the heat exchanger. This tool is ideal for cleaning devices made of copper, brass and stainless steel. Depending on the degree of contamination, recommended concentrations range from 0.5 to 1.5%.

Heater core flushing with citric acid

Detex flushing fluid

Detex is a flushing agent for removing limescale, oxides, salts and various biological deposits from the walls of cast-iron, steel and copper heat exchangers. Due to the content of surface-active substances and corrosion-inhibiting additives it protects the metal, thereby increasing the service life of heating equipment. Depending on the degree of dirt, the cone is diluted with water in the ratio of 1/6 to 1/10 and poured into the washer-dryer.

Picture 6: Industrial Heat Exchanger Flushing Products

The process of circulation of the flushing liquid through the heat exchanger of the gas boiler is accompanied by gas emission, the termination of which indicates the end of the reagent action. If the required flushing quality is not achieved, increase the con until the gassing process resumes and continue the cleaning procedure. In a final step the heat exchanger should be flushed with neutralization liquid, followed by water.

In addition to the above reagents, for flushing gas boiler heat exchangers sulfosalicylic, acetic and oxalic acids are used, as well as industrial chemicals of different brands, such as Steeltex, Alfa Laval, ЕРП-1 in the form of concentrate, which should be diluted with water in the required proportion.

Who should flush the heating system?

Flush the radiators should be the house management company, which you pay a monthly fee under the article “and repair of housing. Here is what the “Rules and norms of technical exploitation of the housing stock” (approved by the Ministry of Education and Science of Ukraine) say in this regard. Post. Gosstroy of 27.09.2003 70):

Specialists recommend flushing heating radiators only after a chemical analysis of the sample plaque. In practice, this recommendation is often ignored, and the frequency of flushing depends on the composition of the coolant, the material of radiators and pipes of the heating system, the temperature mode of operation of equipment.

Briefly about the main things

Every owner of an apartment or house with an individual heating system must understand that the appearance of scale on the heat exchanger is the most dangerous. At first it will cost you a lot of money every month, because you will have to pay more for gas. After the boiler can fail at all.

The problem must necessarily be solved, either independently or with the help of specialists. You can perform a mechanical cleaning on your own, it is recommended to do it every year. Also, in the presence of a booster or similar equipment can be performed and chemical cleaning.

How to clean your Zojirushi Water Boiler & Warmer using Citric Acid Cleaner CD-K03EJU

If even these two methods do not help, then, how to wash the heat exchanger will prompt the masters. They will hydrodynamically clean the heating system and quickly remove even large accumulations.

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