Flushing the gas boiler heat exchanger

The task of any gas boiler is to heat the coolant as efficiently as possible and supply it to the heating system and to heat the water for hot water supply. During the operation of the boiler, the products of gas combustion are deposited on the outer walls of the heat exchanger, and the coolant - most often this is ordinary tap water - clogs the inner surface of the tubes with its deposits. This leads to significant losses in boiler power and, accordingly, an increase in gas consumption, and in the future, if preventive maintenance is not carried out, it can lead to boiler failure. For the efficient operation of boiler equipment, periodic cleaning of the boiler and all its working elements is necessary.

How often do you need to clean the boiler

Every year after the end or before the start of the heating season, a preventive inspection of the boiler for leaks, removal of dust, dirt, cobwebs is recommended. Once every two to three years, it is necessary to clean the gas nozzles, heat exchanger and chimney.

How to clean the boiler yourself: a step-by-step guide

To carry out these works, you will need the following tool:

  • screwdrivers "+" "-";
  • set of open-end wrenches;
  • gas key;
  • a vacuum cleaner;
  • metal brush and soft bristle brush;
  • rags.

Now let's move directly to the step-by-step cleaning guide.

  1. The boiler begins a routine inspection by checking for gas leakage. To do this, a soap solution is prepared and all the connections of the gas pipe from the tap to the burner in the boiler are saturated with soap solution. If a leak is detected, call a specialist company to resolve the problem. In no case should you try to eliminate the gas leak yourself. If the gas pipeline is in order, you can continue servicing the boiler.
  2. All threaded connections are checked for leaks, in case of rusty streaks or hanging drops of water, it is necessary to disassemble the assembly and replace the gasket.
  3. Before proceeding with disassembling the boiler, it is mandatory to turn off the gas supply valve, close the valves on the inlet and outlet pipes of the hot water supply and heating, and disconnect the boiler.
  4. At the initial stage, the boiler body is disassembled. This opens up access to the combustion chamber. For quick and correct work on dismantling the boiler elements, in order not to make mistakes, it is necessary to be guided by the boiler passport and carefully study the equipment diagram.
  5. After removing the outer casing with a vacuum cleaner and brush, all dust and dirt is removed from the inner space, all internal elements are cleaned of dust and dirt.
  6. The pressure in the expansion tank is checked. To do this, you need a regular car pressure gauge. If the pressure is below 1.5 atmospheres, then using a car pump it must be raised to the desired value.
  7. At the bottom of the combustion chamber, the nozzles are cleaned with a brush and rags, and all debris and dust are removed.

Cleaning the heat exchanger of the gas boiler is the main task

The main element of the boiler is a heat exchanger. The heat in the house, the hot water in the faucet in the kitchen or in the bathroom, and the gas costs are directly dependent on the quality of the heat exchanger’s work. Therefore, special attention should be paid to its cleaning.

Types of heat exchangers and how to clean them

The main materials from which heat exchangers are made:

  • steel;
  • cast iron;
  • copper.

Each material has certain advantages and disadvantages. The most versatile is a steel heat exchanger. This is the most affordable material. Main advantages:

  • cheapness;
  • light weight;
  • high ductility.

It is plasticity that does not allow thermal stresses to occur in places of active heating of the material, which prevents the formation of cracks. However, the main disadvantage is the low corrosion resistance, which reduces the service life of steel heat exchangers, entails a second - to extend the service life, manufacturers are forced to increase the wall thickness and diameter of the tubes, which leads to an increase in the amount of coolant, the dimensions of the device and, as a result, an increase in fuel consumption for heating it.

Cast Iron Heat Exchanger practically not subject to corrosion, but has a very low ductility and high weight. Low ductility leads to the fact that at the boundary of strong heating of the metal of the device and its warm part, stresses appear, leading to cracking. This problem is solved by installing a three-way valve, which mixes the hot coolant with the cooled one, which allows the required temperature to enter the fluid heat exchanger.

Copper heat exchanger It has a number of advantages over cast iron and steel. First of all, low weight, respectively, compact size and small internal volume of the device. Compared with steel - high corrosion resistance. Less fuel is required to heat the copper heat exchanger. The disadvantages include the high cost of the material.

In double-circuit boilers, in addition to heating the coolant, the function of heating water for domestic purposes is also performed. There are two types of heat exchangers in them:

  • Dual (bithermic).
  • Separate consisting of two heat exchangers, each of which performs its own function. Primary warms up the heat carrier, and secondary water for hot water supply.

Bithermic heat exchanger It is a pipe-in-pipe system in which the coolant of the heating system moves along the external circuit, and hot water is prepared in the internal circuit. It is located directly in the combustion chamber of the boiler.

In a separate heat exchanger the coolant from the primary heat exchanger heats the water in the secondary. The primary is located in the combustion chamber, and the secondary is moved outside. For the operation of a separate heat exchanger, a three-way valve is used, which directs the flow of coolant, depending on the task, either into the heating system or to prepare hot water.

In a single-circuit boiler, only one heat exchanger is used, which is responsible only for heating the coolant. In order to prepare hot water using a single-circuit boiler, it is necessary to install an indirect heating boiler, which is connected to the heating system.

Heat Exchanger Flushing: Walkthrough

  1. The heat exchanger is disconnected from pipes, sensors and carefully removed from the gas boiler.
  2. After removing this element proceed to its examination. If soot and metal salts are found on the outer parts of the deposits, they proceed to extremely careful removal of plaque using a scraper and a metal brush, taking care not to damage the heat-removing cells.
  3. If it is impossible to remove deposits mechanically, the external surface is cleaned with chemicals. The heat exchanger is immersed in a tank with an aqueous solution of special means, you can also use household chemicals to clean gas stoves, grills and ovens. After several hours of soaking in the solution, the heat exchanger is removed, cleaned of the remnants of the softened deposits and washed under running water.
  4. To clean the heat exchanger at home from internal scum on the tubes, the most suitable and affordable means is citric acid, as the most gentle chemical agent.
  5. To perform this work, service companies use special equipment - a booster, which is a pump with a tank for special flushing fluid and connecting hoses. But it is quite possible to make a booster at home. To do this, it is enough to have a circulation pump and a plastic tank of a suitable size. Principle of operation: a flushed element is placed in the tank, a hose connected to the circulation pump is inserted into one of the openings of the heat exchanger, the second hose emerging from the pump is hermetically connected to the tank at the lowest point. The whole system is filled with a solution of water and citric acid preheated to 70 degrees in the proportion of 20-30 grams of acid per liter of water, and starts up for 2-3 hours of continuous operation. After the end of the process, the heat exchanger is removed, washed with running water from the remnants of the active solution, dried and replaced.
  6. In the absence of a booster, the heat exchanger is placed in a container with a hot solution of water with citric acid in the same proportion. In case of severe contamination, the proportion of citric acid can be increased or a descaling agent can be used, hydrochloric acid solution can be used with caution, as well as a silite type toilet detergent that removes plaque, but citric acid is the most gentle. The heat exchanger is periodically removed from the tank, washed under running water and, if the cleaning process does not reach the goal, is placed back into the preheated solution.
  7. When the desired cleaning result is achieved, the device, after thorough washing under running water, is dried and mounted.

Important points for boiler care

For a long uninterrupted operation of the boiler, it is necessary:

  • Regularly at least once a year, and preferably twice, after the end of the heating season and before it starts, clean the boiler from dust and dirt. These simple manipulations significantly extend the life of the boiler equipment.
  • Once every two to three years, be sure to clean the heat exchanger and the chimney, this will allow the boiler to work with maximum efficiency.
  • Every three years, it is recommended to flush the entire heating system, thereby increasing the heat transfer of radiators.
  • If the cleaning of the boiler and heat exchanger is carried out for the first time, it is recommended to carry out a photo and video recording of their actions, which will avoid errors during installation and assembly of the removed and cleaned boiler elements.
  • An important detail is the savings. The independent implementation of these procedures allows you to save money and be sure that the work is done efficiently.

Watch the video: How To Flush Descale Tankless Water Heater and Maintenance heat exchanger Navien NCB240 Combi Boiler (March 2024).

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