How and what is the best way to flush the heat exchanger of a gas boiler

When living in your home, the heating system accounts for the largest portion of your expenses. It doesn’t matter whether the owner powers his house from the outside or has his own heating system. One of the available options for heating your home is to equip your boiler room with gas. This is not a water boiler, so there will be slightly fewer problems with scale. But not much, because... and this boiler has a heat exchanger heated by gas. And here, too, there will be the hated limescale, spoiling everything in its path. How to flush a gas boiler? Or is it better to invest in a softener? These issues will become the most pressing for boiler house owners.

Why does scale form?

Flushing the heat exchanger of a gas boiler is necessary when scale appears on this unit. This is usually caused by water with increased lime hardness. The “cocktail” that is supplied to home heating systems is based on a high amount of calcium, magnesium and iron salts. Together with constant heating, these elements begin the process of crystallization on metal surfaces.

The liquid usually enters the coolant after undergoing filtration, but it enters the heat exchangers without purification. This unit is most susceptible to scale formation and requires regular washing.

Scale is the main pest Source prokommunikacii.ru

Types of pollution

In most cases, plaque is:

• calcium carbonate;
• fatty and organic sediments;
• deposits of iron oxide and salts;
• limestone.

It is formed during the circulation of liquid with impurities, which regularly accumulate on the internal walls of heat exchange equipment. Without flushing, the thickness of the sediment constantly increases, impedes the movement of the working medium, interferes with the normal operation of the apparatus and reduces its efficiency.

Plates for the heat exchanger before and after washing Source maksom.ru

Washing a collapsible plate heat exchanger is possible chemically and mechanically. The first method does not require disassembling the equipment and is more popular. Mechanical cleaning options are used only in cases of severe contamination; they require dismantling the heat exchanger and require large amounts of time and labor.

Why is scale dangerous?

Few people argue that the problem exists, but not everyone knows what its consequences are. The accumulation of deposits on the fins of the heat exchanger has a bad effect on the operation of the heating system:

1. Increases fuel consumption . Metal is used in heating system components not only because of its rigidity, but also due to its thermal conductivity properties. Scale does not have such thermal conductivity, and the boiler has to spend more time and fuel on heating. Just 1mm of deposits on the heat exchanger and gas bills will increase by 10%.
2. Overheating of the heat exchange element . Heating boilers have a water cooling system that comes from the return line. But when scale forms on the heat exchanger, the system becomes confused, using more force to heat. The problem is fraught not only with increased gas consumption, but also with overheating of the element, which can even damage it.
3. Increased load on the heating system . When formations appear on the surface of the nodes, the channels narrow significantly, which impairs the process of water circulation. The workload of the circulation pump system increases, which is why it can also break down.

The harmful effects of scale Source vyborradiatora.ru

Full disassembly service

Do not be afraid to disassemble the water heating installation, the procedure is not that complicated. You will need the most common tools - screwdrivers, pliers, standard wrenches. What to do before starting work:

1. Close the taps of the cold water, hot water and gas supply pipelines. Unplug the turbocharged dispenser from the outlet.

2. Substituting the container, unscrew the union nuts (American) on the connection of the water pipes. Disconnect the connections from the unit without losing the rubber gaskets.
3. For convenience, it is recommended to remove the gas heater from the wall. It is not easy to disassemble and clean a unit that is hung too high or installed in a narrow niche.
4. To dismantle the water heater, disconnect the gas line and the chimney pipe. Remove the unit from the hooks.

Lay the hot water column on a horizontal surface and proceed to further work, the order of which is outlined in our instructions.

How to remove the heat exchanger and column burner

We will show the disassembly sequence using the example of a cheap Chinese Novatek water heater. We present step-by-step instructions with photos:

1. Remove the control handles mounted on the front panel. Unscrew 2 screws (or 2 plastic clips) and remove the device casing.

2. The next step is to remove the smoke collector. To do this, disconnect the wires from the draft sensor and unscrew the screws holding the diffuser box.

3. Disconnect the heat exchanger tube from the water unit by disassembling the connection with the union nut. The second pipe must be freed from the lock washer, pressed with 2 screws.

4. Disconnect the burner from the gas valve by unscrewing the 2 screws on the flange. Having moved the radiator upward, carefully remove the burner device (pull towards you) and move it to the side.

5. Unscrew all screws connecting the heat exchanger to the rear panel of the water heating unit.

6. Pull out the radiator completely and remove the burner, disconnecting the wires along with the ignition electrodes.

Note. While removing the heat exchanger, disconnect the wires from the temperature sensor.

Disassembly of geysers from other manufacturers may differ, but not fundamentally. The order of work remains unchanged. Let's list some important points:

• in a chimneyless turbo column, the fan will have to be removed;
• in units of the Italian brands Ariston (Ariston) and some others, the pipes are connected not with nuts, but with self-clamps;

• If the water heater is equipped with an igniter, then before removing the burner it is necessary to disconnect the gas tube connected to the wick.

Important! Be careful not to lose any rubber or other gaskets discovered during disassembly. Before assembling and installing the column, it is advisable to replace these seals with new ones.

Our expert plumber will demonstrate the above process in detail in his video:

Flushing procedure

This operation is very simple compared to disassembly - cleaning the gas water heater begins by immersing the heat exchanger in a container with washing liquid. The procedure is as follows:

1. Take a bucket or deep basin, fill it with water and prepare a cleaning solution according to the recipe on the package. The concentration of citric acid is 50-70 grams per 1 liter of liquid.
2. Immerse the heat exchanger in the container with the radiator down and the pipes up.
3. Using a watering can, fill the coil with detergent. Rinse it periodically by adding new solution.
4. Flush the heat exchanger until clean liquid comes out of the tubes without scale flakes. Then run tap water through the coil to remove any remaining product or impurities.

Advice. Using citric acid, heat the solution to a temperature of 50-60 °C. The reaction will be more intense and end faster.

The removed burner can be cleaned from the outside and purged or washed with a solution of citric acid (no more than 50 grams per liter of water). Finally, rinse the element with running water, blow with compressed air and dry thoroughly. Do not ignore other parts of the gas water heater - the mesh filter, smoke collector and combustion chamber, remove soot and other contaminants from them.

After washing and drying, put the heat exchanger back in place, connect the burner and follow the remaining steps to reassemble the water heater. It is important to achieve tight connections: when installing old gaskets, treat them with high-temperature sealant. Check the joints for tightness using water pressure (4-6 bar).

It wouldn’t hurt to blow out the inside of the burner with compressed air at a pressure of 4-6 bar

For reference. The duration of washing depends on the thickness of the scale layer inside the column heat exchanger and ranges from 2-3 hours (prevention) to 2 days.

How often is flushing needed?

The accompanying documentation for heating systems from some manufacturers usually indicates how often the boiler should be flushed. But these are only recommended data for standard operating conditions; the frequency in each individual case is determined by the quality of the water and the load of the boiler.

If the water quality is poor, purification is required every year. And it’s better to do this in spring or autumn, that is, before or after the heating season, and not at its height.

Signs that cleaning is needed:

1. Increased gas consumption . The appearance of scale has a bad effect on thermal conductivity, which means that the boiler will require more fuel for heating.
2. Constantly running burner . This factor also indicates the appearance of formations on the heat exchanger, the boiler is forced to constantly work.
3. Problems with the circulation pump . The narrowing of the channels due to scale increases the load on the pump, so it may hum or even turn off during operation.
4. Reduced pressure in the hot water circuit . Of course, due to the narrowing of the channels, the pressure will also decrease.

Increased gas consumption is a clear sign of a problem Source lanos-club.org.ua
If one or more of these four problems is observed, the heat exchanger needs to be cleaned. And you shouldn’t delay this, because the longer the system works with scale, the faster it will fail.

See also: Catalog of companies that specialize in autonomous gasification of country houses and related work

Special cleaning equipment

A booster (installation for washing heat exchangers) is a rather rare and expensive equipment (40-90 thousand rubles), which is simply unprofitable to buy for personal purposes, no matter how often you clean it. It is a container with a built-in circulation pump that supports a change in flow direction - reverse, which increases the efficiency of washing. The devices are resistant to any reagents used.

PIPAL PUMP ELIMINATE 20 V4V

One of the best Italian-made units. It has compact dimensions and optimal performance - 2600 l/hour (44 l/min). Tank volume – 18 l, permissible pressure – 1 bar. Known for its simplicity and reliability.

BWT Cillit SEK 28

An equally well-known, proven German-made installation. Capacity – 2400 l/hour, the operating principle is no different from the previous installation, designed for higher temperatures – up to 60°C. It has even more compact dimensions and a convenient handle for transportation.

How to choose a water softener for a gas boiler and extend the life of the heat exchanger

Methods for cleaning a gas boiler

One of three methods will help you get rid of formations on the surface of the heat exchanger:

1. manual;
2. chemical;
3. hydrodynamic.

Before performing manual and chemical cleaning, the heat exchanger is removed Source severdv.ru
The need to use a specific option depends on the number of formations on the surface of the unit. You should familiarize yourself with each of the methods in more detail.

Manual method

Cleaning the heat exchanger of a gas boiler is a slightly complicated procedure, but you can do it manually yourself without any special preparation. Manual cleaning is divided into two more stages:

1. Mechanical . It will require a brush and a brush.
2. Flushing with active substances . A little more complicated, but it will help cope with more advanced formations.

A brush is the first assistant in the fight against plaque Source positroika-doma.ru

Cleaning the secondary DHW heat exchanger in double-circuit boilers

In double-circuit boilers, the process greatly depends on the type of heat exchanger: additional secondary or single bithermic.

In the case of the secondary heat exchanger, everything is simple; it is cleaned in exactly the same way as the primary one.

A bithermic heat exchanger is a single structure consisting of a hot water supply circuit pipe inserted into a heating circuit pipe. It is extremely difficult to clean such an internal structure; washing is carried out either chemically or hydrostatically: by specialists using special chemistry and a booster. Heavily contaminated elements, where the clearance is narrowed by more than 80-90%, must be replaced.

Video description

The video shows how to get rid of scale in a boiler

Chemical method

Washing hot water heat exchangers using this method will require the use of a booster or similar devices (even homemade ones). Be sure to follow the recommendations for the concentration of chemicals so that they do not harm the metal of the assembly.

To make a more affordable analogue of a booster yourself, you will need a container with a volume of about 10 liters, a pump and a pair of hoses.

When there is a large layer of deposits on the surface of the heat exchanger, solutions of hydrochloric acid are used. Sulfuric substances are also suitable. If the problem is not so aggravated, a solution of 5 liters of clean water and 200 grams of citric acid will do.

Chemical cleaning Source remont-system.ru

Step-by-step instructions for chemical cleaning:

• dilution of active elements in recommended proportions;
• pouring the finished substance into the booster;
• connecting the booster to the boiler with hoses (inlet and return);
• turning on the booster;
• for high-quality cleaning, the liquid must go through several cycles;
• you need to drain the chemical solution;
• Pump neutralizing liquid or clean water through the system.

The advantage of factory boosters over homemade options is the presence of a heating system, which ensures increased efficiency of the method.

Functional booster for flushing Source gasprofservice.uz

The chemical cleaning option allows you to quickly get rid of all types of contaminants, but it should be used only once every 3-4 years, not more often. The fact is that chemical compounds can contribute to the appearance of rust.

Cleaning soot from a wall-mounted heat generator

Getting to the main heat exchanger of most wall-mounted gas boilers is quite simple. The work algorithm is as follows:

1. Turn off the gas supply by closing the appropriate tap.
2. Remove the front panel of the unit.
3. Unscrew and remove the front cover covering the combustion chamber.

To prevent the removed soot from pouring into the holes of the gas burner and you don’t have to think about how to remove the burner for cleaning, cover the nozzles with a sheet of thick paper or cardboard. After that, use an old toothbrush to clean the fins of the heat exchange unit from carbon deposits. If the stuck layer cannot be removed, you can use a brush with soft metal bristles.

When finished, sweep the inside of the unit with a brush and carefully remove the sheet of paper with soot. How to service a wall-mounted boiler is shown in detail in the video:

Briefly about the main thing

Every owner of an apartment or house with an individual heating system should understand that the appearance of scale on the heat exchanger is extremely dangerous. At first, it will hit your pocket every month with increased gas bills. Afterwards, the boiler may completely fail.

The problem must be solved, either independently or with the help of specialists. You can perform mechanical cleaning on your own; it is recommended to do it every year. Also, if you have a booster or similar equipment, you can perform dry cleaning.

If these two methods do not help, then the experts will tell you how to flush the heat exchanger. They will carry out hydrodynamic cleaning of the heating system and quickly remove even large accumulations.

We service the igniter and water intake unit

If there is a need to clean the water unit, do not rush to disassemble the entire device. Take a look at the operating instructions for the water heater, find the “frog” in the diagram and follow the following algorithm:

1. Remove the adjuster knobs and front cover.
2. Dismantle the water unit by disconnecting the pipes.
3. Unscrew the screws holding the cover, remove it and get to the membrane.
4. Clean the filter - mesh and water holes in the frog body using a wooden stick or soft copper wire. Remove scale with a brush.
5. Rinse the parts with water and assemble the assembly. Replace damaged or cracked membrane immediately.

Clean the pilot burner jet (wick) with thin copper wire or a toothpick moistened with alcohol. Wipe the ignition electrodes and the flask of the flame sensor (thermocouple) thoroughly from soot, otherwise over time the column will begin to turn off spontaneously.

Neutralization of the washing solution

When you have finished flushing your gas boiler, you will need to neutralize the flushing solution. To do this, stock up on regular soda. And then there are two options:

Or you pour all the flushing solution into a separate container, call the Ministry of Emergency Situations, and they take the solution to a solid waste landfill (just kidding). Or you start adding a little soda to the intermediate tank. The pump is still running. The soda will react with the acid, fizz, and neutralize the latter. At the same time, you measure the pH, and as soon as it reaches 6-7 units (neutral), this solution can be poured into the sewer. It is advisable, in this case, to add cold water to the intermediate tank and drain the solution with a temperature of less than 50°C. These are the regulatory requirements of one of the RD (guidance document) dedicated to chemical washing.