1. The chimney must be resistant to acid corrosion
The chimney must be made of materials with increased resistance to acid corrosion. It is one thing when hot combustion products pass through the pipe, and quite another when condensate forms in it, a concentrated acid with a pH of 3 to 5.
2. The chimney must provide free discharge of condensate into a special reservoir
This tank (boiler) must be equipped with a siphon water seal filled with water to prevent flue gases from entering the drain pipe.
5. A constant supply of air is needed
For normal operation of the condensing boiler, it is necessary to organize a constant flow of air to it. This can be done in several ways, for example, by taking air from the room if there is a sufficient supply of it. If there is not enough supply air, the air flow is organized through the same chimney, which is usually made in the form of a concentric pipeline for this (coaxial chimney). Outdoor air enters through the inner pipe, and flue gases are removed through the outer pipe.
6. It is necessary to correctly determine the length of the chimney
The length of the chimney cannot be arbitrarily large, it is determined by the fan power of a particular boiler model. For each model of the condensing boiler, it has its own, and is indicated in the technical characteristics of the product. For example, the De Dietrich VIVADENS MCR‑P 24 model is recommended to be connected to a coaxial chimney with a horizontal ending and with an air duct diameter of 60 mm and for flue gases of 100 m. And the length of this chimney should not exceed 6 m if it has a horizontal ending (outlet a pipe segment exits horizontally through the wall of the house) or 20 m if the coaxial chimney has a strictly vertical design.
The editors would like to thank De Dietrich for their help in preparing the material.