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.

A cantilevered window unit is provided that can be attached to a wood stove. The window unit allows a flue member to pass through the unit and extend upwardly on the outside of the structure containing the window unit. A unique roof bracket is employed to secure a vertical section of the flue member to the structure. Extension brackets can be employed in combination with the roof bracket to provide further support above and/or below the roof bracket location depending on the length of the flue member above or below the roof line.

A cantilevered window unit is provided that can be attached to a wood stove. The window unit allows a flue member to pass through the unit and extend upwardly on the outside of the structure containing the window unit. A unique roof bracket is employed to secure a vertical section of the flue member to the structure. Extension brackets can be employed in combination with the roof bracket to provide further support above and/or below the roof bracket location depending on the length of the flue member above or below the roof line.