In individual residential applications, a chimney ensures the safe and efficient operation of a single appliance. The most common scenarios are condensing combi boilers/boilers (P1–W–O) and wood-burning fireplaces/stoves (N1–D–G). Single-wall construction is generally preferred for interiors, while double-wall construction is preferred for exteriors; condensate drainage, distance from the burner, and aesthetic finishes are critical factors. For exterior applications and corrosion risk, 316L (L50) is recommended; appliance declarations and local regulations are used as a guide.