DIY chimney insulation methods

As a rule, a gas or solid fuel boiler is installed to heat a private house in the cold season. A reliable and high-quality channel is required for the removal of combustion products. The structure must be strong and durable so that it can serve throughout the entire life of the building. Thermal insulation of the chimney helps to achieve these goals, without the high costs of construction and subsequent maintenance. The modern market is saturated with heat insulators that differ in appearance, properties and technical characteristics. In order not to get confused in the variety of products offered, you should familiarize yourself with its features, installation rules, advantages and disadvantages.

Necessity and advantages of chimney pipe insulation

When building their own mansion, many land owners underestimate the role and importance of communications for the removal of gases released during the combustion of fuel. By leaving the pipe open to the environment, they risk losing their property and their own lives.

An insulated chimney pipe is a necessity justified by the following factors:

• The chimney gets very cold in winter cold. It takes a lot of energy to heat it, which entails a decrease in the temperature of the coolant and an increased fuel consumption.
• The difference between the internal and external temperature of the pipe walls leads to the formation of condensation. When mixed with smoke, it forms a corrosive substance that corrodes even stainless steel.
• On the moisture formed in the channel, solid particles of combustion products settle, which leads to the appearance of solid deposits. The draft deteriorates, the risk of complete clogging of the pipe and smoke in the room where the boiler is installed increases.
• The dew point is low, as the gases escaping from the furnace cool quickly. An insulated chimney is devoid of a dew point as such, because its temperature is the same throughout, and the inner walls do not come into contact with cold air.
• Brick channels are the most vulnerable. Moisture is absorbed into the brick, and when it freezes, it tears apart the material, causing slow but steady destruction of the entire structure.

If, immediately after construction, the chimney is insulated, the productivity of the stove will increase and the safety of the inhabitants of the house will increase.

Insulation materials

Fuel consumption, efficiency and service life of the structure largely depend on the correct choice of thermal insulation.

The material must meet the following qualities:

• low thermal conductivity;
• light weight;
• water resistance;
• fire resistance;
• ecological cleanliness;
• the possibility of arrangement with your own hands.

You should not pay attention to the price, since first of all the priority is given to reliability and durability.

To insulate the chimney pipe, the following materials and technologies are used:

• Plaster. The mixtures of the facade type are selected, which are equally resistant to heat, cold and humidity. Plaster is used for finishing brick and stone canals. The mortar is applied to a mesh or lattice reinforcement cage. This technique is characterized by high labor costs and low efficiency.It is rarely used, for the most part to create a uniform style for courtyard buildings.
• Expanded clay. An analogue is broken red brick and crushed slag. Initially, the casing is made of metal, plastic or waterproof drywall. Then the material is poured into the casing and compacted. The downside is that the filler absorbs moisture and gradually settles under its own weight, while losing its insulating qualities.
• Mineral wool. A modern, ideal in all respects heat-insulating material, suitable for finishing pipes of any configuration and composition. Mats, rolls and ready-made cylinders (shells) are used. Basalt wool made from dolomite rocks has the best performance. The insulation is screwed on, glued or wrapped around the pipe, after which it is closed with an external protective screen. A prerequisite for the installation of mineral wool is the use of a membrane film to remove moisture.

When choosing a material for insulation, you need to objectively assess your skills and scope of work. It may be necessary to involve an assistant in order to comply with the technology and safety measures during complex manipulations.

The design of the insulated chimney and its features

Regardless of the type of boiler, the chimney must be insulated. In its final form, this structure consists of the following parts:

• Smoke extraction duct. It is an internal part, which can have a round, square and rectangular cross-section. Manufactured from materials that can withstand the intense heat generated by fuel combustion. Throughout its length, the inner shell can have a different composition, but must retain the same channel area.
• Outer shell. Designed to hold and protect the internal filling from the effects of natural factors - moisture, ultraviolet radiation, insects, birds and animals. As a rule, it is done in a form corresponding to the internal channel. The fastening of the outer shell is carried out so as to exclude the formation of cold bridges. In this case, the casing should be made in such a way that it does not spoil the appearance of the house, but organically complements it with its design.
• Insulation layer. Serves to create a thermal insulation barrier between the inner channel and the outer shell. On the one hand, the filler prevents overheating of structures in contact with the chimney. On the other hand, the inner channel does not come into contact with the cold air of the street. Thanks to this, the pipe does not cool down, the draft improves, the formation of condensation and soot is excluded.

By their design, chimneys are divided into internal and external.

In the first case, the pipe runs vertically along the entire height of the building through the floor slabs, attic and roof. This option is good because there are no corners and bends along the channel. Such structures are distinguished by high-quality traction, ease of cleaning and preventive maintenance. The downside is that you have to make holes in the supporting structures and perform complex waterproofing work. Thermal insulation issues are resolved depending on the type of heating in the house. If there is a water circuit in living rooms, it is better to insulate the pipe, leaving it open in the attic to ensure it warms up. When there are solid fuel stoves in the building, it is better to use the hot pipe as one of the elements of the heating system and heating water for domestic purposes.

If you lay the chimney outside, you can save time and effort on passing the ceilings. However, such pipes require better insulation as they will be exposed to cold and moisture. The downside is that to bring the channel out into the street, you will have to make turns along its length, which negatively affects traction. The solution is to use curved inserts or connecting bends with a bend angle of no more than 45 degrees.

Insulation methods for different types of construction

Each type of chimney has its own insulation technologies and a choice of insulating materials.

• Asbestos-cement pipes. The substance has a slight hygroscopicity, but it is also enough for the pipe to suffer during temperature changes. The asbestos channel conducts heat well, it is best to seal it with mineral wool, close it on top with wider stainless steel pipes. The minimum distance between the walls should be 6 cm. The assembly is carried out from the bottom up. After installation, the sections are filled with insulation, then fastened with bolts or rivets. The joints are sealed with a sealant, and a cement plug is made on top to protect against moisture.
• Steel structures. It should be borne in mind that the iron chimney has a high thermal conductivity and transfers all the heat from the burning fuel. You can insulate a metal chimney pipe with your own hands by plastering it or by enclosing it in a cocoon of tin and mineral wool. In the first case, a fiberglass mesh is wrapped around the channel, on top of which a solution is applied. If necessary, the procedure is repeated several times until the desired effect is achieved. Making sandwich sections is more expensive and time consuming, but this method is much more practical. Sockets are made at the ends of the pipes, after which narrow fragments are wrapped with insulation, and wider workpieces are tightly fitted on top of it.
• Brick chimneys. It is advisable to insulate the chimney pipe on the street in a private house immediately after the masonry dries. The material is porous, absorbs moisture, mold, moss and even grass quickly appear on it. The best option is a combined approach. First, the brick is coated on the outside with a heat-resistant cement-based mortar. Then a frame is made from a metal profile. Mineral wool mats are inserted inside, and a membrane film is attached over the frame. The final stage is the sheathing of the frame with a profiled sheet. The material is beautiful, strong and durable.

Knowing how to choose and insulate the chimney correctly, you can easily and easily do this work yourself.

Do-it-yourself chimney insulation

It is recommended to take measures for the thermal insulation of the chimney in the warm season, during dry and calm weather. These conditions are necessary to minimize the likelihood of injury.

For work, you will need the following tools, devices and materials:

• puncher, screwdriver;
• level, tape measure;
• hammer, hacksaw for metal, riveter;
• trowel, spatula, paint brush;
• safety equipment, safety helmet, goggles and gloves, gauze bandage or respirator;
• chimney sweep ruff.

The list can be more or less, depending on the material of the chimney and the selected technology.

The insulation process consists of the following stages:

1. Design. A detailed diagram is drawn up indicating all distances, parts, methods of fastening and connections. Based on the drawing, a calculation of building materials is made, and a step-by-step work plan is also outlined.
2. Preparatory phase. The workplace is equipped, the availability and serviceability of the equipment is checked, the condition of the safety equipment is checked.
3. Cleaning the chimney from dirt and soot. First you need to clean the channel from soot. After insulation, the temperature in the pipe will rise, which can lead to fire and fire. Then you should clean the outer surface of unstable fragments, dirt and vegetation.
   
4. Pipe processing. The metal is coated with an anti-corrosion agent, asbestos cement and brick - with a deep penetration primer, which strengthens the material and protects it from moisture swelling.
5. Installation of insulation.It can be inserted into the frame, glued, screwed on or simply wrapped around and then fixed with ties or wire.
6. Installation of the outer casing. The choice depends on the shape and material of the pipe. After fastening, the ends and joints are sealed.
7. Finishing and cleaning of the remaining construction waste.

Soot forms even in the insulated chimney. It should be inspected on a quarterly basis and cleaned if more than 2 mm of soot forms on the inner walls.