System and method for controlling a furnace

摘要

Controlling a modulating gas furnace by monitoring a differential pressure associated with the modulating gas furnace using a low pressure limit switch configured to actuate at a first pressure, an intermediate pressure limit switch configured to actuate at a second pressure, and a high pressure limit switch configured to actuate at a third pressure, the second pressure being between the first and third pressure, selectively operating the modulating gas furnace in one of a cycling mode, a modulating mode in a lower range, and a modulating mode in an upper range, the modulating mode in the lower range being associated with an output capacity range between the output capacity ranges of the cycling mode and the modulating mode in the upper range, and selectively operating the furnace in response to at least one of the low pressure limit switch, the intermediate pressure limit switch, and the high pressure limit switch.

主权项

1. A modulating gas furnace, comprising:
a modulating combustion system, comprising:
a burner assembly;a modulating gas valve assembly configured to modulate an amount of fuel gas delivered to the burner assembly as a result of a measured pressure differential; andat least one of (1) a pressure sensor configured to measure the pressure differential and (2) a low pressure limit switch, an intermediate pressure limit switch, and a high pressure limit switch, wherein each of the low pressure limit switch, the intermediate pressure limit switch, and the high pressure limit switch are configured to actuate at different pressure differential values; wherein the measured pressure differential is measured between an upstream pressure tap disposed in a combustion space and a downstream pressure tap disposed within a header; and wherein the modulating combustion system is configured to selectively maintain steady state operation at a plurality of firing rates within at least one of a cycling mode, a modulating mode in a lower range, and a modulating mode in an upper range.