Sandwich chimneys are considered the best option for removing combustion products from stoves, especially in wooden baths. We offer you to familiarize yourself with the technology of installation of double-walled chimneys and the features of their designs. Content:
- Chimney requirements
-
Choosing a sandwich chimney
- Pipe section
- Selection of material
- Connecting elements
- Preparatory work
- Installation procedure
- Wall mount
- Passage through the attic
- Roof passage
A sandwich chimney is the simplest option for self-assembly of a combustion product removal system. Lightweight and compact structural elements are quickly assembled using auxiliary elements. Of course, when assembling a sandwich pipe for a bath, a number of points must be taken into account.
General requirements for the chimney in the bath
The following requirements affect the size and design of the chimney in a sandwich pipe bath:
- The optimal length of the pipe from the stove to the fungus on the roof is 5 m.
- The pipe is mounted vertically without ledges. The permissible deviation of the pipe from the vertical is 30 degrees, with a maximum deviation to the side - 1 meter.
- If the size from the roof to the head of the pipe is more than 1.5 m, install a brace to fix the structure.
- If the roof is covered with flammable materials, install a spark arrestor mesh 5x5 mm at the end of the pipe.
- A pipe on a pitched roof should protrude 50 cm above the ridge. A pipe on a flat roof should be 1 m higher than the roof.
- The horizontal part of the smoke exhaust duct is up to 1 m.
- The joints of the pipe elements must remain in sight; they are not allowed to be located inside the roof ceilings.
- It is forbidden to place cleaners, horizontal bends in the attic. The pipe in the attic should point upwards.
How to choose a chimney sandwich for a bath
The sandwich chimney is made by connecting separate parts of the chimney with a length of 1 m. Each section of the structure consists of three components - an inner and an outer pipe with a heat-resistant layer. The chimney also requires fasteners and accessories. Double-walled chimneys are manufactured in many designs and differ in their parameters - diameters, type of insulator and its thickness, pipe material, etc. To avoid mistakes when choosing elements of a sandwich pipe, use the recommendations.
Determination of the cross-section of the chimney for a bath
The chimney must have the same cross-section as the outlet flange of the furnace. If necessary, you can determine the section of the pipe for the furnace by calculation using the requirements of SNIP:
- For a 3.5 kW boiler, pipes with a cross section of 0, 14x0, 14 m are used.
- For a boiler with a capacity of 3, 5–5, 2 kW - 0, 14x0, 2 m.
- For a boiler with a capacity of 5, 2-7 kW - 0, 14x0, 27 m.
Find out or calculate the thermal power of your furnace and determine the cross-sectional area of the chimney, which will ensure compliance with the SNIP requirements. Pick up a sandwich chimney with a round shape according to the calculated cross-sectional area.
Selection of pipes for a bath by material
The inner pipe of the chimney is made of stainless steel. If possible, choose the pipe with the thickest wall, it is more rigid. Do not buy a pipe with a wall less than 1 mm. The outer pipe can be made of any metal, even galvanized steel. It is better that the outer pipe is also made of stainless steel - when heated, the material practically does not lengthen, which cannot be said about a galvanized sheet.
Stainless steel pipes are only externally the same. When purchasing, you can determine the quality of the products as follows:
- Try to find out the composition of the pipe metal. Quality samples are made from austenitic steel with the addition of molybdenum, chromium, nickel. These substances help to resist corrosion and acidic substances.
- Inspect pipe welds. Burnt seams are not allowed.
- Stainless steel pipes are expensive. You can reduce the cost of installing a sandwich pipe in a bathhouse if you make a combined chimney: in a steam room with high humidity, high fire safety requirements and in order to give a representative look, install stainless steel elements, in other places - galvanized.
- For a bath, buy a sandwich pipe with a heat-insulating material that can withstand temperatures over 800 degrees. Such characteristics are possessed by asbestos, mineralized, expanded clay heaters.
- The thickness of the insulator layer with the same material properties can be from 20 to 60 mm, so before buying, be sure to ask about the composition and properties of the insulation.
Connecting pipe elements for a bath
On the market you can find samples that are joined together and fixed in different ways - flange, bayonet, "cold bridge", but for a bath it is recommended to choose between "smoke" or "condensate" connection.
The difference between the connections is as follows:
- The smoke connection ensures that no smoke escapes through the joint into the room. But, on the other hand, condensate flowing down the walls of the pipe can get through the cracks inside the sandwich and harm the insulation.
- In the “condensate” connection, the inner pipe of the upper sandwich goes into the socket of the lower pipe, so moisture does not get onto the insulation. In this case, there is no guarantee that the smoke will not leak out.
- The customer independently chooses the connection method. For premises, the "smoke" method is usually chosen, because a small amount of condensate is formed in the sandwich chimneys.
- When buying, check the quality of the docking of the modules. Samples from a single source will provide a good connection.
Preparatory work before installing the pipe in the bath
Before installing the sandwich pipe in the bath, or rather even at the stage of building the foundation of the furnace and roof, check the location of the chimney axis. The pipe should not cross the rafters and beams of the attic and roof and should not be located at a distance of less than 25 cm from the wall. It is possible to pre-assemble the stove and chimney to a minimum. The work is performed when at least the subfloor is ready and the wooden roof elements are fixed.
Place the stove on a sub-floor. Align the device in its original position in a vertical plane, taking into account the height of the "pie" of the floor and the thickness of the floor covering. Lower the plumb line from above to the center of the furnace outlet flange and observe the results. If the supporting elements of the roof do not intersect with the plumb line, cut off the excess elements to allow the installation of the pipe. Postpone major work until the floor is finished.
Instructions for installing a chimney in a bath
The procedure for installing a sandwich pipe for a stove in a bath looks like this:
- Install the ceiling-pass assembly (PPU) in the place where the pipe passes through the ceiling.
- Install the first pipe piece on the exhaust flange of the furnace, which must be single-walled. The sandwich pipe is mounted starting from the second level.
- Install alternately double-walled pipes and the rest of the chimney elements (tees, elbows - if the design of the pipe requires), bring them through the ceiling, fix them to each other and to the walls.
- Insulate the pipe passage to the attic.
- An audit with a stand for inspecting the internal cavity of the pipe and cleaning soot and other similar elements should be mounted up to the attic.
- Continue installing the chimney in the attic and bring the chimney out to the roof. Only sandwich pipes are allowed in the attic, additional elements are prohibited.
- Insulate where the pipe passes through the roof.
- Secure the outside of the pipe with braces (if it protrudes high above the roof). Install a spark arrester and a fungus on top of the finished product.
Fastening a sandwich pipe in a bath to the wall
The pipe is narrowed on one side, so for assembly it is enough to install one pipe in the other. To seal the gaps and joints, a chimney sealant is used that can withstand a temperature of 1000 degrees. The absence of gaps in the joints increases traction.
When connecting pipes, adhere to the following rules:
- The sealant is applied to the inner pipes from the outside of the upper inner pipe.
- On the outer pipes - on the outer surface of the upper pipe.
- At the joints of a single-wall pipe with a chimney, a sandwich or with other modules - outside, in a circle.
- Sandwich pipes are connected with clamps on one side.
- Sandwich pipes are connected to tees and adapters with clamps on both sides.
- The pipes are fixed to the wall with brackets every 2 m.
- The tees are fixed to the supporting structures with brackets.
Chimney passage in the bath through the attic floor
Installation of a sandwich pipe in a bath should be carried out in accordance with the requirements of SNIP in terms of thermal insulation of the chimney when passing through wooden floors. The temperature in the furnace, especially if heated with wood, reaches 800-1000 degrees. It easily heats the chimney (and boards in the ceiling) to a high temperature critical for wood.
To ensure the safe passage of the pipe through the attic floor, a ceiling-through unit (PPU) is used. The product is made in the form of a box measuring 300 x 300 mm. There is a hole in the horizontal wall through which the sandwich pipe passes. PPU made of stainless steel or galvanized iron can be found ready-made on the market. The device is mounted in the ceiling opening prior to pipe assembly.
Thermal insulation of the pipe in this place is performed in the following order:
- Install the PPU in the opening in the ceiling together with the heat insulator and fix it.
- Install the sandwich pipe on the lower elements so that the connection is above the attic floor.
- Check that there is a gap of at least 130 mm between the pipe and the ceiling.
- This gap can be left unsealed, but it is better to fill the inner space between the pipe and the PPU walls with mineral wool.
- Cover the joints at the bottom and top with stainless steel sheets. Also place a heat insulator between the sheets and the ceiling.
The passage of the chimney in the bath through the roof
Consider the features of the passage of a sandwich pipe through the roof:
- Make sure that the distance from the pipe to the ceiling wall is at least 130 mm.
- Cut the roof sheet out of the steel sheet. It is a sheet with an internal hole equal to the pipe diameter and dimensions larger than the opening in the ceiling.
- Slide the roof sheet over the pipe.
- Pass one end of the pipe through the roof opening from the attic side, and install the other end into the lower pipe.
- From the roof side, install the lead base (roof corner cut) onto the pipe and lower it onto the roof. Knock the base with a hammer and drive it to the surface of the crumb.
- From the attic side, fill in the gaps between the pipe and the ceiling with basalt cardboard and basalt wool.
- Lift the roof sheet all the way up and secure with wood screws.
- To seal the joint, cover the joint with a rubber-based bitumen roofing sealant.
Video instructions for installing a sandwich pipe in a bath with your own hands:
Installation of a sandwich chimney is a laborious work that requires concentration and attention from the performer. The main thing is to choose high-quality materials that will ensure the reliability and safety of heating the bath.
