Embodiments of the present disclosure relate to a selectively-closable hatch for automatically preventing airflow through the blower inlet of a fuel-burning grill. The hatch has a first, normal, resting closed configuration which prevents the flow of air through the inlet and into the cooking chamber of the grill, and a second, open configuration which is obtained when a fan is engaged to create a forceful airflow through the inlet path. The force of air pushed against the hatch pushes the hatch open, both when the fan is disengaged or falls below a minimum strength, the hatch returns to the closed configuration and prevents air from being drawn or otherwise flowing through the inlet path into the cooking chamber of the grill.

A damper regulator for controlling the opening/closing characteristics of an HVAC damper has a swing arm coupled to the shaft on which the damper pivots. The swing arm has an arm carriage mounted to translate on the swing arm as the swing arm pivots, and a biasing spring connects the arm carriage to the damper regulator's housing, or to another suitable anchor. The translation of the arm carriage effectively adapts the characteristics of the biasing spring so that the damper need not be subjected to ever-increasing pressure to achieve greater airflow, or so that other damper opening characteristics can be achieved.

A damper regulator for controlling the opening/closing characteristics of an HVAC damper has a swing arm coupled to the shaft on which the damper pivots. The swing arm has an arm carriage mounted to translate on the swing arm as the swing arm pivots, and a biasing spring connects the arm carriage to the damper regulator's housing, or to another suitable anchor. The translation of the arm carriage effectively adapts the characteristics of the biasing spring so that the damper need not be subjected to ever-increasing pressure to achieve greater airflow, or so that other damper opening characteristics can be achieved.

A flow control device for an appliance including a burner and a blower for delivering a pre-mixed mixture of air and gas to the burner includes a flange defining an opening through which the pre-mixed mixture of air and gas flows from an outlet of the blower to the burner. A damper plate is provided in the opening downstream of the blower for increasing a static pressure at the outlet of the blower during ignition of the burner.

A furnace including a combustion chamber for burning fuel can have increased fuel burning efficiency, increased heating efficiency, and decreased harmful emissions of combustion byproducts. A combustion air delivery system delivers primary and secondary combustion air to the combustion chamber. Primary and secondary combustion air may be delivered at amounts that increase burning efficiency. An amount of secondary combustion air can be controlled by a valve system. A heat transfer device efficiently transfers heat from products of combustion for heating an enclosed space.

A furnace including a combustion chamber for burning fuel can have increased fuel burning efficiency, increased heating efficiency, and decreased harmful emissions of combustion byproducts. A combustion air delivery system delivers primary and secondary combustion air to the combustion chamber. Primary and secondary combustion air may be delivered at amounts that increase burning efficiency. An amount of secondary combustion air can be controlled by a valve system. A heat transfer device efficiently transfers heat from products of combustion for heating an enclosed space.

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 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 water heater includes a vessel (20) provided with a burner (3) having a downward combustion surface, a fan casing (10) accommodating a fan (10a) for supplying a mixture gas of primary combustion air and fuel gas to the burner, an annular packing connecting a first connection end surface at a downstream end of a first passage forming a downstream-side passage of the fan casing with a second connection end surface at an upstream end of a second passage forming an upstream-side passage of the vessel in airtight state, and a check valve (5) disposed near the upstream end in the second passage (2).

A water heater includes a vessel (20) provided with a burner (3) having a downward combustion surface, a fan casing (10) accommodating a fan (10a) for supplying a mixture gas of primary combustion air and fuel gas to the burner, an annular packing connecting a first connection end surface at a downstream end of a first passage forming a downstream-side passage of the fan casing with a second connection end surface at an upstream end of a second passage forming an upstream-side passage of the vessel in airtight state, and a check valve (5) disposed near the upstream end in the second passage (2).