A method is provided for controlling airflow into a furnace that employs a velocity type damper. In one embodiment, the method for controlling airflow may include engaging a velocity type damper to an air port opening of a furnace. The velocity type damper includes at least one air controlling surface that is positioned proximate to a wall of the furnace at the air port opening so that air velocity exiting the at least one air controlling surface is substantially equal to the air velocity entering the air port opening to the furnace. The method may further include adjusting a cross sectional area through the velocity type damper to control air velocity into the furnace through the air port opening.

A flue damper may include a vent pipe with a first side leading to an outlet of the flue damper and a second side leading to an inlet of the flue damper. A damper gate of the flue damper may be movable between an open state and a closed state, where in the open state, the first side of the vent pipe is in fluid communication with the second side, and where in the closed state, the damper gate interrupts fluid communication between the first side and the second side. A drainage port may also be included, and a plug may be movable relative to the drainage port to selectively seal the drainage port when the damper gate remains in the closed state.

A flue damper may include a flue pipe with a first side leading to an outlet of the flue damper and a second side leading to an inlet of the flue damper. A damper gate may be included and have an open state and a closed state, where in the open state, the first side of the flue pipe is in fluid communication with the second side, and where in the closed state, the damper gate interrupts fluid communication between the first side and the second side. A float may be secured to an upper surface of the damper gate. The upper surface of the damper gate may face the first side of the flue pipe when the damper gate is in the closed state such that the damper gate at least partially opens when condensate collects within the first side of the flue pipe.

A flue damper may include a flue pipe with a first side leading to an outlet of the flue damper and a second side leading to an inlet of the flue damper. A damper gate may be included and have an open state and a closed state, where in the open state, the first side of the flue pipe is in fluid communication with the second side, and where in the closed state, the damper gate interrupts fluid communication between the first side and the second side. A float may be secured to an upper surface of the damper gate. The upper surface of the damper gate may face the first side of the flue pipe when the damper gate is in the closed state such that the damper gate at least partially opens when condensate collects within the first side of the flue pipe.

A damper for a furnace, the damper including an air port damper body engaged to an air port opening of a furnace; and at least one velocity plate in hinged engagement to the air port damper body so that an air controlling end surface of the at least one velocity plate is substantially aligned to a wall of the furnace at the air port opening when the at least one velocity plate is in a fully opened position.

A damper for a furnace, the damper including an air port damper body engaged to an air port opening of a furnace; and at least one velocity plate in hinged engagement to the air port damper body so that an air controlling end surface of the at least one velocity plate is substantially aligned to a wall of the furnace at the air port opening when the at least one velocity plate is in a fully opened position.

This application is directed to a device and method for providing a variable orifice restrictor to an air induction system to achieve an improved turndown ratio of an airflow rate. The devices of the invention improve turndown ratio by relying on a pressure differential.

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.

An electronic control device includes: a flow rate calculation unit that calculates a flow rate of intake air based on an output signal of a flow rate measurement device assembled to an intake pipe; a flow rate correction value calculation unit that calculates an average value, a maximum value, and a minimum value of the flow rate of the intake air, calculated by the flow rate calculation unit, during a predetermined period, and an amplitude of a signal with one or more frequencies equal to or higher than a fundamental frequency of the output signal of the flow rate measurement device and included in the output signal of the flow rate measurement device, and calculates a correction value for the flow rate of the intake air based on calculation results; and a flow rate correction unit that corrects the flow rate of the intake air based on the correction value.