Chimney cleaning: how to clean the chimney from soot

Recommendation points

• Why chimneys are clogged?
• Chimney inspection
• Soot and soot cleaning products
• Mechanical cleaning of channels
• Precautions and Prevention of Contamination

Many types of heating systems that run on combustible fuel require vigilant attention and maintenance of the chimney ducts. In our review, we will consider the causes of chimney clogging, the means and methods for cleaning them, as well as the rules for maintaining them in working order..

Why chimneys are clogged?

The combustion processes of different types of fuel are very different. If the combustion of natural gas produces only carbon dioxide and water, the combustion products of wood, fuel oil and coal are more diverse. Burning, solid fuel emits a large amount of smoke, which contains sulfur and nitrogen compounds, and most importantly – unburned carbon residue. It is solid soot particles that represent the bulk of the pollution that accumulates in the chimney..

To ensure the most complete combustion of the fuel, a very high temperature is required in the combustion seat. Soot burns out at 1100 ° C, but such a heat is destructive for the material of the furnace; moreover, from a purely technical point of view, such conditions cannot be realized in home heating equipment. So, the formation of by-products during the combustion of solid fuel is inevitable, but at the same time, in some boiler houses the chimneys remain relatively clean for several years, in others, the channels are almost completely clogged in a couple of months..

The main reason for the accumulation of carbon deposits in the chimney is water. When dry fuel is burned, the vast majority of soot is carried away by the flow of combustion products and released into the atmosphere. If a large amount of water evaporates during combustion, as happens when burning raw firewood, soot particles bind, become more heavy and viscous, due to which they stick to the walls of the chimney. In addition, the presence of moisture on the channel walls can also contribute to carbon deposits. If hot gases pass through a cold pipe, then a small amount of moisture condenses on the pipe surface, which inevitably forms during combustion. Soot sticks to wet surfaces much more intensively, which is why chimneys need to be insulated.

Chimney inspection

The condition of the flue ducts must be checked at least once a year – at the beginning of each heating season. Typically, only the longest acceleration section needs to be inspected, which requires access to the top of the tube. If there is a deflector or a protective cap, they must be removed and visually assess the clearance in the pipe by shining a flashlight inside. There are several types of pollution:

1. Porous dry soot build-ups indicate that the chimney is operating normally but has not been cleaned for a long time. With further operation, the clearance will gradually decrease, which will lead to a deterioration in traction.

2. Viscous resinous formations on the walls indicate that wet fuel is constantly burned in the boiler, or the chimney needs to be insulated. Such contamination builds up much faster than dry soot, besides, the resin gradually flows down, which is why there is less clearance in the lower part of the pipe, which is very difficult to notice during external examination.

3. The chimney may be clogged with debris such as fallen leaves or nesting areas of small animals. In this case, the operation of the chimney is impossible, it is required to immediately remove the blockage..

Soot and soot cleaning products

Before you start cleaning the chimney, it will not be superfluous to try to apply special chemicals. They are sold under different brands: Kominicek, Chimney sweep, Spalsadz, Sadpal, but all have approximately the same composition and principle of operation. Chimney cleaners are a collection of inorganic salts that, when heated, form volatile active substances that react with carbon compounds. In essence, the process of chemical decomposition of soot is similar to the catalytic cleaning of a car’s exhaust gases. After decomposition, the soot falls off the walls of the chimney and is carried outside by a stream of hot gases. The effect of cleaning chemicals is especially useful for removing carbon deposits from the heat exchanger and those parts of the flue system that are difficult to access..

The use of chemicals for cleaning chimneys is predominantly prophylactic, but they can also be used immediately before mechanical cleaning. After decomposition, the carbon deposits become loose and easier to remove; moreover, when dirt falls off, the risk of clogging up the pipe is reduced. Before cleaning, you need to apply chemistry 2-3 times more concentration than provided by the instructions. In this case, it is advisable to maintain active combustion of the boiler or stove for several hours using only dry wood or coal.

Mechanical cleaning of channels

Manual removal of soot is required in cases where the thickness of the build-up on the walls exceeds 5–7 mm. However, if the chimney has not been serviced for a long time, carbon deposits can occupy more than half of the pipe section, therefore, several methods are provided for cleaning..

To remove thin plaque, a round steel brush is used, suspended on a cable along with a ball-shaped weight, the shape of which will not allow it to get stuck in the pipe. The diameter of the bristles in the widest part should be 10–20 mm larger than the chimney section. For ducts with a special inner coating, nylon brushes should be used; their diameter should be 50–70 mm larger than the pipe. The cleaning principle is simple: the brush is pulled up and down inside the pipe until all carbon deposits are removed from the walls. Periodically, the brush must be removed to clean the bristles from adhering soot and visually determine the location of the most problematic areas of the chimney.

During the cleaning process, the soot falls down, so all inspection hatches and the valve on the boiler must be closed. If the chimney of the fireplace is being cleaned, its firebox must be covered with a thick film, which is hermetically glued with tape to the outer walls of the arch. After cleaning is complete, you need to wait a while until the soot settles, and then carefully remove the bulk of it with a scoop, and the rest with a damp cloth or a washing vacuum cleaner.

In some cases, it is not possible to access the top of the pipe. In such situations, the boiler should be dismantled and cleaned from below. For these purposes, disc brushes are provided, mounted on a long flexible rod. Such a device can also be made independently using brass brushes for a grinder and a metal-plastic pipe.

Removal of stubborn dirt from the chimney should be carried out using a straight or semicircular blade (depending on the shape of the chimney channel). It is important to start cleaning strictly from one side so that crumbling carbon does not clog the pipe. If the channel is completely clogged, the clog is pierced with a massive metal rod tied to the cable. After removing the bulk of the dirt, the chimney must be thoroughly cleaned with a brush.

Precautions and Prevention of Contamination

Chimney cleaning is a hazardous work. The main threat is soot, the suspension of which is explosive in the air, moreover, it is a carcinogenic substance and does not stay in the upper respiratory tract. Take special care when working on the roof: secure the ladder securely and use a safety rope tied to the chimney pipe.

When cleaning yourself, there is always a risk of dropping the instrument into the canal, therefore, all devices must be tied with a cord. For the same reasons, you should not use homemade devices and irregular weights..

To avoid intensive clogging of the chimney, you should use high-quality fuel: year-old hardwood firewood, or better briquettes or pellets. Periodically, it is necessary to use chimney cleaning agents and at the same time always remember: regular cleaning always costs less effort than building a new chimney or dismantling an old one to eliminate a blockage that cannot be broken through.