Safety devices prevent packaged catalytic converters from being expelled from stacks, or at least reduce the velocity with which such a package may be expelled, in case of an explosion in a bio-fueled appliance, such as a wood-burning stove.

A method and apparatus of reducing thermal shock in one or more radiant tubes of a pyrolysis furnace is provided. The apparatus is a furnace comprising a blower and blower bypass conduit providing separate fluid communication paths for flue gas from the convection section to a natural draft flue gas stack. The method comprises the steps of: redirecting at least a portion of the flue gas through the blower bypass conduit when a blower shut-off event is indicated as well as reducing the firing rate of the furnace.

A sensor network system for determining a chimney maintenance schedule comprises a sensor unit (16) arranged for placement in or proximate to a chimney (6). The sensor unit comprises at least one sensor arranged to measure a parameter of the chimney (6) and use the measured parameter to generate chimney health data associated with the chimney (6). The sensor unit includes a transmission module arranged to transmit (20) the chimney health data to a remote analysis unit (18). The remote analysis unit (18) is arranged to receive chimney profile data associated with the chimney (6) and to estimate a chimney health level associated with the chimney (6) from the respective chimney health data and chimney profile data. The remote analysis unit (18) determines the chimney maintenance schedule from the estimated chimney health level.

A non-return valve for a flow channel has a housing and an outflow opening that can be closed by a pivoting blocking flap. The blocking flap has a dome-shaped bulge. An opening edge of the outflow opening has a hinge region for the blocking flap that transitions into a blocking flap stop region circumferentially opposite the hinge region. The blocking flap stop region is offset so that the opening edge has a progression that is curved in the circumferential direction and in the outflow direction. The housing has an indentation in the circumferential direction, which is not closed by the blocking flap such that the indentation forms a condensate chamber when the housing is inserted into the surrounding flow channel. The indentation is equipped with a flow opening, through which a condensate accumulating in the condensate chamber delimited by the indentation can flow in the interior of the housing.