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.

A heater can be configured to operate with either a first fuel at a first pressure or a second fuel at a second pressure. In some embodiments, a pressure regulator unit is configured to regulate the pressure of either the first fuel or the second fuel and to direct either the first fuel or the second fuel towards a combustion chamber. A nozzle assembly can be configured to inject the fuel into the combustion chamber.

A heater having first and second oxygen depletion sensors and a main burner injector and configurable for the delivery of at least first and second types of fuels.

A method of controlling the temperature within a heating apparatus for eliminating or reducing combustion resonance, the method including measuring a temperature of the burner assembly; comparing the measured temperature with a predetermined temperature limit or range; determining whether the measured temperature is greater than a predetermined temperature limit or range; performing a controlled action if the measured temperature is greater than the predetermined temperature limit or range.

A variable capacity furnace includes a variable capacity fuel valve configured to supply a fuel to a burner, where the variable capacity fuel valve is configured to be controlled to a target setting over a range of settings to modulate an amount or flow rate of the fuel supplied to the burner. The variable capacity furnace also includes a control assembly having processing circuitry and memory circuitry. The memory circuitry includes instructions stored thereon that, when executed by the processing circuitry, cause the processing circuitry to execute a control algorithm to determine, based on whether an indoor temperature is progressing toward a set point over time and based on a temperature differential between the set point and the indoor temperature, a target setting of the variable capacity fuel valve. The instructions also cause the processing circuitry to control the variable capacity fuel valve to the target setting.

A furnace system includes a heat exchanger and a burner assembly including a burner enclosure fluidly coupled to the heat exchanger. The burner assembly is configured to receive a fluid, ignite the fluid to produce combustion byproducts, and direct the combustion byproducts to the heat exchanger. The furnace system also includes a pressure sensor configured to detect a pressure within the burner enclosure. The furnace system is configured to operate based on the pressure detected by the pressure sensor.

In accordance with various embodiments of the present disclosure, a control system for a hybrid air heating system is provided. In some embodiments, the hybrid air heating system has at least one electric heating element capable of generating an electric thermal output and at least one burner capable of generating a combustion thermal output. In some embodiments, the control system comprises a controller configured to, based on a desired total thermal output of the hybrid air heating system, determine an amount of the desired total thermal output of the hybrid air heating system to be generated by the at least one electric heating element and an amount of the desired total thermal output of the hybrid air heating system to be generated by the at least one burner.