01
Fresh Air Intake
Cold, fresh air enters the system through the terminal vent at the rooftop or wall exit and flows downward through the outer channel of the concentric pipe assembly.
LAS Air/Exhaust Gas chimney systems
Kapella LAS Air/Exhaust Gas Chimney Systems — Balanced Flue Technology for Hermetically Sealed Appliances
Hermetically sealed (room-sealed) boilers and heating appliances require a dedicated air supply path alongside the exhaust gas discharge. Kapella's LAS (Luft-Abgas-System) chimney systems deliver both functions within a single concentric assembly — drawing fresh combustion air inward while simultaneously expelling flue gases outward through separate, counter-flow channels.
The LAS system operates on a coaxial principle: two concentrically joined liners form an inner pipe for flue gas discharge and an outer channel for fresh air intake. Cold, fresh air enters from the terminal vent at the top and travels downward through the outer channel to the hermetically sealed appliance. As it descends, the incoming air absorbs heat from the inner flue gas pipe, pre-warming the combustion air and increasing boiler efficiency. Flue gases travel upward through the inner pipe in the opposite direction and are safely expelled to the atmosphere — without any contact with the room environment.
This counter-flow design delivers measurable efficiency gains by recovering heat that would otherwise be lost through the chimney. Because the system is completely sealed, no indoor air is consumed for combustion, making LAS systems ideal for airtight modern buildings, passive houses, and energy-efficient construction where uncontrolled air infiltration must be avoided.
Kapella LAS systems are manufactured from AISI 316L stainless steel with continuous TIG/WIG welding and precision laser cutting. Every system includes purpose-designed modules — tee connections, clamp rings, cleaning access points, pressure balance components, condensate drainage, and carrier brackets — ensuring a complete, code-compliant installation from appliance connection to atmospheric terminal.
All Kapella LAS systems are CE approved and compliant with EN 1856, designed for C-type (room-sealed) gas appliances. Our engineering team provides full system specification including sizing calculations, route planning, and component selection for your specific appliance and building configuration.
How a LAS Air/Exhaust Gas System Works — Step by Step
02
Air Pre-Heating
As fresh air descends through the outer channel, it absorbs heat radiating from the inner flue gas pipe. This pre-warming effect increases combustion efficiency and reduces energy consumption.
03
Combustion
Pre-warmed air reaches the hermetically sealed appliance and is used for combustion. No room air is consumed — the system operates as a completely closed circuit.
04
Flue Gas Discharge
Exhaust gases travel upward through the inner pipe in counter-flow to the incoming air, passing through the tee module, pressure balance, and cleaning module before being safely expelled through the terminal vent.
Why Choose Kapella LAS Air/Exhaust Gas chimney systems?
- Complete Concentric Solution — A single coaxial assembly handles both combustion air supply and flue gas discharge, eliminating the need for separate air ducts and chimney pipes.
- Energy Efficiency Gains — Counter-flow heat exchange between incoming air and outgoing flue gases pre-warms combustion air, measurably improving boiler efficiency and reducing fuel consumption.
- Hermetically Sealed Operation — Zero room air consumption makes Kapella LAS systems the ideal choice for airtight buildings, passive houses, and modern energy-efficient construction standards.
- Modular Component System — Every component — from tee modules and clamp rings to cleaning access and condensate drainage — is designed as a plug-in module for fast, precise installation.
- EN 1856 Certified & CE Approved — Full compliance with European chimney standards for C-type room-sealed appliances, backed by Kapella's in-house engineering calculations per EN 13384.
Frequently Asked Questions
LAS stands for Luft-Abgas-System (Air-Exhaust Gas System). It is a concentric chimney design that combines fresh air intake and flue gas exhaust in a single coaxial pipe assembly, specifically designed for room-sealed (C-type) heating appliances.
Fresh air entering through the outer channel absorbs heat from the inner flue gas pipe as it travels toward the appliance. This counter-flow heat exchange pre-warms the combustion air, meaning the boiler uses less energy to reach optimal combustion temperature — resulting in measurable fuel savings.
Yes. LAS systems are ideal for airtight construction because they draw combustion air entirely from outside the building through a dedicated channel. No indoor air is consumed, maintaining the building's air barrier integrity and indoor air quality.
C-type (room-sealed/hermetical) gas boilers and heating appliances require a LAS chimney system. These appliances have sealed combustion chambers with no direct connection to room air, relying entirely on the LAS system for both air supply and exhaust discharge.
Condensate forms naturally when flue gases cool inside the inner pipe. Kapella LAS systems include integrated condensate course channels that guide moisture downward to a sealed drainage exit at the base, where it connects to the building's waste water system.
Yes. Kapella LAS systems support both vertical (through-roof) and horizontal (through-wall) configurations using appropriate tee modules, bends, and terminal components. The system route is determined by the appliance location and building design.