In this article I’ll explain to you what a Direct Vent System is. A Direct Vent System is a chimney or an exhaust pipe with two parallel flow channels (double-pipe flue). The hot exhaust gas of the fireplace is discharged over the inner channel and fresh air supplies the heater simultaneously with combustion air over the outside channel.
What are the Advantages of a Direct Vent System?
- The boiler doesn’t require room air for the combustion process (Power Vent System). For the combustion it draws its air over the supply air channel.
- The supply air is heated up by the hot exhaust gases, resulting in an energy-saving effect.
- Direct Vent Systems are particularly suitable for multi-family houses and airtight buildings.
I sketched the idea of a Direct Vent System in Illustration 1. Two flow channels lead fresh air to the heater and the exhaust gases are led to the outside via the exhaust pipe. During that process we have a heat transfer inside the chimney from the exhaust air to the supply air. The heated supply air no longer needs to be heated up as much in the heater. The preheating of the supply air saves energy.
If you have any questions about a Direct Vent System, leave a comment.
Best regards! Martin
Further links and sources:
Title picture: Schornsteinwerk K. -H. Schreyer GmbH,
modified, License: CC BY-SA 4.0
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