Single-family homes today are built to be very airtight and well insulated. Because of this design, it makes sense to supply the combustion air for a fireplace from the outside.
For room-sealed fireplaces (for example, gas fireplaces), the law requires the use of so-called LAS chimneys. Custom-built wood-burning fireplaces, on the other hand, are formally classified as room-air-dependent fireplaces. Still, it also makes sense here to supply the combustion air from the outside through a closed duct system. These heating inserts generally have a suitable connection port and are built to be airtight.
The equivalent to the LAS in the area of room-air-dependent fireplaces is the LAF chimney (air-exhaust-solid fuel chimney). In addition to the flue gas duct, it has an integrated air shaft. This shaft is thermally separated from the exhaust pipe and approved by the manufacturer for combustion air supply. Such a system can therefore be connected to any room-air-dependent individual fireplace.
Air-exhaust system for gas fireplaces
LAS systems are only available for room-sealed fireplaces. The system unit consists, for example, of BRUNNER gas fireplaces combined with the BRUNNER LAS (Gas) system, which is designed as a concentric, sealed double-pipe system. The inner metal pipe carries the exhaust gases outside, while the outer pipe supplies combustion air directly to the gas fireplace.
A thermal separation is not necessary with this variant since a gas fireplace reaches operating temperature almost immediately. The gas insert and chimney form a certified system unit. The BRUNNER LAS for gas fireplaces is flexible in installation and can also be added later.
Air-exhaust-solid fuel systems (LAF) for wood-burning fireplaces
In an LAF chimney designed for wood-burning fireplaces, two ducts run parallel to each other. The flue pipe and the air shaft are both built into the masonry chimney, with a thermal separation between them. This ensures that no heat from the exhaust system is transferred to the air supply. This separation is essential for wood fireplaces, as sufficient chimney draft is needed for proper operation.
Where are LAS chimneys suitable?
The chimney sweep knows which LAS chimney system is suitable for a particular building or construction project. They can also determine whether multiple connections are possible. The specialized stove retailer can provide information about compatible fireplace models.
Conclusion
Air-exhaust systems offer a perfect and compact installation level for efficient flue gas and combustion air management. For room-air-dependent wood-burning fireplaces, the combustion air duct can also be routed through the floor structure, the basement, or the exterior wall to the outside. This ensures that the fireplace always receives enough oxygen for clean combustion and prevents oxygen depletion inside the room, which could negatively affect the indoor climate. For carefree enjoyment of your fireplace or tiled stove.
Expert advice
Always consult a professional when making technical decisions. The chimney sweep or a specialized stove retailer can provide reliable and competent advice. You can find certified stove builders on our website under Experience BRUNNER.
