A vent proving system is described for use with a gas fired appliance. The gas fired appliance includes a gas burner, a vent damper for selectively opening or closing an exhaust vent from the gas fired appliance and a relay control for operatively controlling the vent damper and the gas burner to open the damper if the gas burner is on. The vent proving system comprises a sensor for sensing a variable in the vent representing air flow direction in the vent. An electrical switch is connected in series between the relay control and the vent damper. A controller is operatively connected to the sensor, the electrical switch and to the relay control.

A damper system comprises a damper slide adapted to couple to a wall with a first outlet. In one embodiment, the damper slide has a first opening and is adapted to operate in a first position and a second position. In the first position, the first opening is at least partially aligned with the first outlet. The first opening and the first outlet are at least partially offset in the second position.

A non-return valve having an accumulation damper movable relative to a housing and shaped like a bowl to accumulate condensate running down from the chimney. The non-return valve has a smaller floating damper made of a material having a density less than water for resting against the accumulation damper when the appliance is in standstill and sealing the drainage holes in the accumulation damper when the condensate accumulation is below a threshold. Once condensate accumulates in the accumulation damper beyond the threshold, the floating damper is buoyed by the condensate thereby breaking the seal with the drainage holes and permitting the condensate to drain through drainage holes in the accumulation damper. When the appliance is operational, exhaust from the appliance lifts the floating damper and, in some cases, the accumulation damper also, to permit exhaust of combustion gases up the chimney.

A vent proving system is described for use with a gas fired appliance. The gas fired appliance includes a gas burner, a vent damper for selectively opening or closing an exhaust vent from the gas fired appliance and a relay control for operatively controlling the vent damper and the gas burner to open the damper if the gas burner is on. The vent proving system comprises a sensor for sensing a variable in the vent representing air flow direction in the vent. An electrical switch is connected in series between the relay control and the vent damper. A controller is operatively connected to the sensor, the electrical switch and to the relay control.

A combined combustion device comprises: a plurality of combustion units (2) each having a burner (4) and an air supply fan (5); an exhaust collecting pipe (10) connecting the plurality of the combustion units (2) to each other; and a check valve (7) which opens by rotation of the air supply fan (5) and prevents backflow of combustion exhaust gas from the exhaust collecting pipe (10) into each of the combustion units (2), wherein when one or more of the combustion units (2) among the plurality of the combustion units (2) are in a combustion operation state and the other one or more of the combustion units (2) are continuously maintained in a non-combustion operation state for a predetermined reference stoppage time or longer, the air supply fans (5) of the other one or more of the combustion units (2) are rotated for a certain time.

A vent proving system is described for use with a gas fired appliance. The gas fired appliance includes a gas burner, a vent damper for selectively opening or closing an exhaust vent from the gas fired appliance and a relay control for operatively controlling the vent damper and the gas burner to open the damper if the gas burner is on. The vent proving system comprises a sensor for sensing a variable in the vent representing air flow direction in the vent. An electrical switch is connected in series between the relay control and the vent damper. A controller is operatively connected to the sensor, the electrical switch and to the relay control. The controller determines if a back draft condition is present in the vent when the gas burner is on and selectively operates the electrical switch to open the connection between the relay control and the vent damper if a back draft condition is present in the vent when the gas burner is on.

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 system to reduce standby losses in a hot water heater is presented. The system utilizes a dual safety relay valve between the combination gas controller and the burner. The dual safety relay valve bypasses gas to a rotary damper actuator valve to position a damper flapper valve located over/inside the flue pipe. Once the flapper valve has opened to ensure combustion, the gas is allowed to flow back to the dual safety relay valve. Some of the bypass gas may be diverted to boost the pilot or to supply a booster. The dual safety relay valve is then opened to allow the gas supply to the burner. Once the burner is turned off, bypass gas bleeds out of the rotary damper actuator valve to close the damper flapper valve to reduce standby losses through the flue pipe, and to allow the dual safety relay valve to close tightly.

A safety switch that prevents the flow of gas in a gas operated fireplace or furnace when a damper is in a closed position, and only allows the gas flow when the damper is in an open position. The safety switch is mechanically connected to the damper and electrically connected to a gas line valve. When the damper is in an open position, the safety switch allows the gas to flow, or conversely, when the damper is in a closed position, the safety switch prevents the gas from flowing. The safety switch also may provide for audio or visual alerts to indicate the open or closed status of the damper.

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.