A control system for controlling a gas powered appliance includes a hot surface igniter, an igniter relay, and an integrity detection circuit. The integrity detection circuit is configured to be coupled to a power source, the igniter relay, and the hot surface igniter to produce an output indicative of the integrity of the hot surface igniter and the igniter relay. The integrity detection circuit is configured to output a first voltage when the igniter relay is closed and output a second voltage different from the first voltage when the hot surface igniter is in a non-short circuit failure condition.

A flue shield and mesh baffle are described for use within HVAC systems and inside of a combustion chamber. The shield or baffle can be installed around the burner and within the combustion chamber to help dissipate heat that builds up as a result of the combustion of gas and air. An air gap is created between the flue shield and the inner surfaces of the combustion chamber and heat exchanger tubes. A mesh baffle can provide heat insulation and noise dampening. Installation of a flue shield or mesh baffle provides better efficiency than insulation solutions, reduces stresses on the heat exchanger, and provides safety benefits.

A method of controlling a gas furnace system includes determining a first pressure in a conduit coupled to a draft inducer from signals output by a pressure transducer positioned to sense a pressure within the conduit with a motor of the draft inducer in a stopped condition. A first status of the pressure transducer is determined based at least in part on the first pressure. The motor of the draft inducer is controlled to increase a speed of the motor from the stopped condition in response to a call for heat when the first status does not indicate that the pressure transducer is unreliable, and the motor is maintained in a stopped condition when the first status indicates that the pressure transducer is unreliable.

A method of controlling a gas furnace system includes controlling a motor of a draft inducer coupled to a conduit to increase a speed of the motor from a stopped condition in response to a call for heat, and receiving pressure signals output by a pressure transducer responsive to pressure in the conduit. Signals indicating whether a pressure switch responsive to pressure in the conduit is in a first state or a second state are received. A first status of the pressure transducer is determined based on the received pressure signals from the pressure transducer and the signals indicating whether the pressure switch is in the first state or the second state. The method includes continuing to operate the motor when the first status does not indicate that the pressure transducer is unreliable, and stopping the motor when the first status indicates that the pressure transducer is unreliable.

A fuel-fired heating appliance comprises a fuel source, an air source, a chamber in which fuel and air mix, a burner downstream from the mixing chamber, an igniter proximate the burner, a heat exchanger, a blower and a flue pipe. An ambient air inlet may be defined by at least one of the outlet end of the blower and the flue pipe extending between the interior of the flue pipe and an area ambient to the flue pipe. A flow rate of combustion gas may be controlled to a level below a steady-state flow rate during appliance warm-up.

A heater includes short and tall cabinet units that are connected together, and an ignition unit. The short cabinet unit has a recess facing upwardly, and a first receiving space spatially communicated with the recess. The tall cabinet unit has a second receiving space spatially communicated with the first receiving space. The ignition unit includes an ignition seat disposed in the recess, an igniter mounted to the ignition seat, and a gas pipe group connected to the igniter and extending from the first receiving space into the second receiving space. A height of the short cabinet unit ranges from 45 centimeters to 60 centimeters; a height of the tall cabinet unit ranges from 65 centimeters to 70 centimeters.

A furnace includes a gas burner exposed to a heat-exchange tube. An inducer is fluidly coupled to the heat-exchange tube and configured to induce draft air through the heat-exchange tube. A regulator is fluidly coupled to the gas burner. A rollout shield is disposed adjacent to the gas burner. A rollout switch is disposed in the rollout shield. The rollout switch is electrically coupled to the regulator. At least one vent is formed through the rollout shield adjacent to the rollout switch. The vent provides a path for a rollout flame to the rollout switch. The at least one vent is disposed on at least two sides of the rollout switch.

A fuel-fired heating appliance comprises a fuel source, an air source, a chamber in which fuel and air mix, a burner downstream from the mixing chamber, an igniter proximate the burner, a heat exchanger, a blower and a flue pipe. An ambient air inlet may be defined by at least one of the outlet end of the blower and the flue pipe extending between the interior of the flue pipe and an area ambient to the flue pipe. A flow rate of combustion gas may be controlled to a level below a steady-state flow rate during appliance warm-up.

A gas fueled water heater appliance may include a tank for storage of water, a chamber wall, a gas burner, a gas conduit, a support post, and a guide bracket. The chamber wall may define a combustion chamber and a conduit hole. The gas burner may be positioned adjacent to the tank and within the combustion chamber. The gas conduit may extend from the gas burner and through the conduit hole. The support post may be fixed to the gas burner within the combustion chamber. The guide bracket may be mounted within the combustion chamber and define a mounting point. The guide bracket may be in selective engagement with the support post at the mounting point. The guide bracket may include a pair of lateral arms extending outward from the mounting point toward the chamber wall to guide the support post to the mounting point.

A method is provided for controlling combustion in a modulating gas furnace. The method includes receiving an indication of a firing rate setpoint for a burner assembly, and applying the firing rate setpoint to first and second continuous functions that map the firing rate setpoint to air-to-fuel ratio and combustion system pressure setpoints. A variable-speed draft inducer blower is set to drive to a combustion system pressure setpoint, and the modulating gas valve is controlled during combustion in the combustion system. In this regard, a combustion system pressure measurement is obtained and applied to an inverse of the first continuous function that outputs an adjusted firing rate for the combustion system pressure measurement. The adjusted firing rate is applied to a third continuous function that maps the firing rate to gas valve position, and outputs a gas valve position to which the modulating gas valve is set.