A soundproof fume discharge conduit adapted to be arranged between a ventilation system and an outlet chimney, the conduit defining a fume path therein, wherein at least one side surface of the conduit is provided with at least two protrusions, each protrusion internally defining a respective step-shaped recess, whereby the path is provided with at least two step-shaped recesses adapted to reflect sound waves propagating along the path, and wherein the step shape of each recess is defined by two first walls, which are incident at a first end thereof, and at least one wall of the two first walls is coated with a first sound absorbing material.

Provided is a heating device exhaust gas arrangement with an integrated sound suppressor, having: a rigid exhaust gas pipe (1) which is made by bending and longitudinally welding a perforated metal sheet and which has an un-perforated, curved first pipe section (2), an un-perforated second pipe section (3) and, formed integrally with the first pipe section (2) and the second pipe section (3), a perforated sound suppressor section (4) between the first pipe section (2) and the second pipe section (3), and a sound suppressor housing (5) which externally covers the perforated sound suppressor section (4) and which is arranged such that the first pipe section (2) and the second pipe section (3) both extend at least predominantly outside the sound suppressor housing (5).

This invention refers to the energy sector and can be applied in heating systems, in particular in water heaters or boilers; in disposal systems operating on associated gas flaring. The pulsating combustion device comprises a combustion chamber and, connected thereto, an air and fuel gas supply unit and a flue duct. Said flue duct comprises at least one resonance pipe connected to the combustion chamber and at least two Helmholtz resonators located successively downstream of the at least one resonance pipe. Each of said resonators consists of a flue chamber and a flue pipe arranged downstream thereof, and natural resonance frequency of each of the Helmholtz resonators is less than combustion pulsation frequency. The invention allows to increase the pulsating combustion device efficiency with a simultaneous reduction of the noise level.

A soundproof fume discharge conduit adapted to be arranged between a ventilation system and an outlet chimney, the conduit defining a fume path therein, wherein at least one side surface of the conduit is provided with at least two protrusions, each protrusion internally defining a respective step-shaped recess, whereby the path is provided with at least two step-shaped recesses adapted to reflect sound waves propagating along the path, and wherein the step shape of each recess is defined by two first walls, which are incident at a first end thereof, and at least one wall of the two first walls is coated with a first sound absorbing material.

A sound level reducing apparatus and method for reducing the outdoor sound level produced by a high efficiency gas furnace. The apparatus comprising a muffler having an internal length determined by an identified target pure tone frequency producing an undesirable sound level. The internal length may be optimized to reduce the sound level across a range of operational frequencies.

A sound level reducing apparatus and method for reducing the outdoor sound level produced by a high efficiency gas furnace. The apparatus comprising a muffler having an internal length determined by an identified target pure tone frequency producing an undesirable sound level. The internal length may be optimized to reduce the sound level across a range of operational frequencies.

An exhaust flue includes an exhaust chimney body, and an open end multi-hole area. The exhaust chimney body defines a passage for discharging exhaust gas. The open end multi-hole area is an area in which multiple holes are defined around a total circumference of an open end of the exhaust chimney body.

An exhaust case having the first exhaust gas flow path for flowing combustion exhaust gas passing upward through a heat exchange, behind a water-shielding plate and for guiding the combustion exhaust gas onto the water-shielding plate toward an exhaust vent, and having the second exhaust gas flow path for flowing a part of combustion exhaust gas into a space between the water-shielding plate and a horizontal plate part and further into the exhaust vent. A ventilation hole is provided for an upright plate part extending from the rear end of the horizontal plate part in order to flow combustion exhaust gas into the space, and is provided in the substantially horizontal direction. Accordingly, the exhaust case is inhibited to become large scaled, and a superior exhaust noise-reduction effect, a suppression effect of combustion oscillation of the burner, and a waterproof performance are able to be achieved.