How do I change the casing of my chimney?

Your fireplace is old and you would like to refurbish it and especially to current standards, which are NF DTU 24.1. So you have to buy the right material and mount it the right way. One of the key elements for an efficient evacuation is the installation of a casing, it must be done by following a few tips.

Choosing the right tube between flexible and rigid

These two tubes each have their particularity, for example the flexible tube is to be preferred if the duct is not straight, but if you are in the case of a straight duct, you can choose between rigid or flexible. This is not the only particularity that must be taken into account to make your choice, because other differences are to be known between these two tubes.

Flexible tubing

The flexible tube is a double wall chimney casing, which has a smooth interior. It is generally made to measure, to respect the dimensions of your duct. Its diameter is between 80 to 250 mm and is made of stainless steel.

Rigid casing

The rigid tube is a stainless steel casing, its diameter is between 80 and 200 millimeters. The advantage of this tubing is that you can assemble it with other pipes that will have other different sizes, whether in length or diameter, you just need to put the right fittings.

Prepare the chimney so that it is stable and secure

The advantage of this tubing is that you can assemble it with other pipes that will have other different sizes, whether in length or diameter, you just need to put the right fittings. You will need to check the condition, but also see if there are any disturbing elements, such as bird nests.

If at the time of inspection you notice that your chimney is in poor condition, you will have to do additional masonry work. And if you encounter obstacles, remove them and do the sweeping at the same time.

Once the necessary has been done, you can begin the work of changing the casing.

Start the casing assembly

At the time of assembly, you will need to apply a necessary space, between the outer wall and the fuel material. This spacing is applied for your safety and is governed by standard NF DTU 24.1.

It indicates that a height of 5 cm² is needed for the opening and for the bottom 20 cm², without forgetting to put the elements in the right direction, the male must be on the bottom and the female on top.

In order not to make a mistake, you will have an additional indication represented by an arrow, defining the direction of the discharge. For step by step details of the installation, click here, but here is the essential in a few points depending on the tube.

Installation procedure for a rigid pipe

  • Start by removing the cap, present on the chimney flue.
  • Assembly process, in the form of a puzzle, starting from the bottom to go up
  • To keep everything stable, fix the tubes with each other, with sealing collars, as well as locking clips

Installation procedure for a rigid pipe

  • Before you begin, you should measure the length of tubing, which you will need. Remember to allow for a margin of error in case of deviation
  • From there you can remove the chimney cap
  • As for a rigid tube, you will have to fix the parts using clamps
  • You can then rearrange the chimney cap

What not to do, video explanation

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