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 high turndown furnace for an air handling system. In one example, the furnace includes a plurality of tubes divisible by four with a first modulating valve supplying gas to of the tubes and a second modulating valve supplying gas to of the tubes. In one aspect, the furnace is capable of providing a 16:1 turndown. In one aspect, the furnace is capable of providing seamless turndown operation throughout the entire firing range.

The disclosed technology includes systems and methods for detecting an at least partially obstructed air filter in a furnace. The disclosed technology can include a system and method that can receive temperature data from a flame sensor configured to detect a temperature of a flame in a burner, determine that an air filter associated with the burner is at least partially obstructed by determining that the temperature data indicates the flame temperature is greater than or equal to a threshold temperature, and output an alarm signal indicating that the air filter is at least partially obstructed.

A gas heater (10) includes heater burner (16). Heat is generated by the ignition of gas supplied to the burner via conduits (20). A solenoid gas safety valve (22), when provided with a threshold electrical current, is maintained in an open condition allowing passage of gas to the burners. When not provided with that threshold current, the valve is closed, preventing the passage of gas. An electrical current generator (28) includes spaced apart thermocouple devices (30, 32). Due to a combined electrical current generation by the thermocouples, the current generator can generate electrical current at least said threshold current even if any one of the thermocouple devices does not generate the threshold electrical current.

A heating assembly can include a locking valve with a reset switch which can include certain pressure sensitive features. These features can be configured to change from a first position to a second position based on a pressure of a fuel. The valve can be used with either a first fuel or a second fuel different from the first. The valve can become locked or be held in either the first or the second position. For example, a set fuel pressure can cause the valve to move to a closed position and the valve can become locked or held in that position. If the pressure decreases, the valve can remain in the locked position. Actuation of the reset switch can allow the valve to move to a new position, such as an open position. The locking valve can be linked to additional valves to lock them in position as well.

A modulating heating system includes a tube heat exchanger having a plurality of burners, a combustion air blower (CAB) having an exhaust vent connected with the plurality of burners, the CAB operable at a first speed and a second speed, a first valve connecting a fuel source to a first subset of the plurality of burners, and a second valve connecting a fuel source to a second subset of the plurality of burners, wherein the first and second valves each have a low fire rate and a high fire rate. The heat exchanger is operable through multiple heat stages at a constant fuel-air mixture.

An apparatus for heating petroleum, petrochemical, chemical process fluids, and boiler feed water or steam generation with a combination, or individual operation, of electrical elements and fired burners. The apparatus includes a radiant heating section and a flue gas stack for exhausting a combustion gas to the atmosphere. The radiant section includes one or more process coils, one or more fuel-fired burners for combusting a fuel and producing the combustion gas, where the one or more fuel-fired burners are arranged to provide radiant energy to a first area of the one or more process coils, and one or more electrical heating elements arranged to provide radiant energy to a second area of the one or more process coils. The one or more electrical heating elements are configured to provide 5% or more of a combined maximum energy output of the fuel-fired burners and the electrical heating elements.

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.

An ammonia decomposition system includes: a reactor filled with a catalyst for a decomposition reaction where ammonia which is a raw material is decomposed into hydrogen and nitrogen; and a diluent gas supply line for supplying a diluent gas having a lower ammonia concentration than the raw material, such that the diluent gas is mixed with the raw material before the raw material flows into the catalyst. The reactor has an inner surface covered with a refractory material, and the catalyst is filled on a side opposite to the inner surface across the refractory material. The diluent gas supply line is provided with a temperature raising device for raising a temperature of the diluent gas.

A dark radiator includes a first burner, a fan and a radiant tube. The first burner is connected to a fuel gas supply, the fan is designed to supply the first burner with combustion air and the first burner is designed to output a flame into the radiant tube. The fuel gas supply is connected to a hydrogen source as a fuel gas source and a secondary burner is connected downstream in the radiant tube spaced apart from the first burner functioning as the primary burner in the flame direction. The fuel gas supply thereof is connected to a hydrogen source as a fuel gas source and the exhaust gas flow of the upstream primary burner is supplied to the secondary burner as combustion air.