Retrofitting a chimney - is that possible?

If a chimney is needed, but none of the building itself can be retrofitted. In what way this can happen, and which criteria must be taken into account, the following contribution provides information.

Criteria for choosing the right chimney

  • Type of plant
  • Performance of the plant
  • possibly required supply air duct
  • Cost of retrofitting in the middle of the house

Type of plant

Depending on which heating system is operated on the chimney, the conditions are different. Modern heating systems today require in most cases a simple exhaust system.

These are stainless steel pipes that can be easily attached to the house wall. The dimensioning of the exhaust pipe also depends on the performance of the system. Common are internal diameters of 140 or 160 mm for most modern heating systems, whether they are operated with oil, gas or pellets.

Stoves and tiled stoves usually require not only an exhaust system, but a veritable chimney.

Performance of the plant

The performance of the system plays a role in the dimensioning of the inner diameter. The higher the system performance, the larger the inner diameter.

However, as the train decreases with increasing diameter, a computational optimization with respect to the length of the chimney, the required diameter and the respective exhaust gas temperature must be carried out.

The calculation bases for the dimensioning are listed in DIN 13384 part 1 and partly in DIN 4705 part 2.

The chimney sweep can also provide information about the required dimensioning. He must also remove the chimney and the fireplace first, before the operation may be included.

possibly required supply air duct

Modern residential buildings, which are insulated according to the EnEV, have a high building impermeability. In such buildings, wood-burning stoves must no longer remove their supply air from the room air. Your performance would be limited and the reliability is not fully guaranteed.

For such stoves so a special supply air guide must be present so that they can obtain the necessary for the combustion air from the chimney head. When retrofitting a chimney on which a stove is to be operated, this must be taken into account.

Cost of retrofitting in the middle of the house

Subsequent installation of a conventional chimney in the middle of the house is feasible. However, the cost is usually higher than retrofitting along the outside wall of the house. The higher cost should be justified at least technically or structurally.

Tips & Tricks

For all retrofitted fireplaces a building permit must be requested. The chimney sweep should be included in the planning.

Video Board: Stove installation with an external steel chimney