A high-efficiency modulating gas furnace (herein ‘gas furnace’) includes a furnace controller. The gas furnace further includes a gas valve and at least one pressure switch that is coupled to the furnace controller. The electrical contacts of the at least one pressure switch are removed from a series electrical circuit with the gas valve such that the gas furnace operates without de-energizing the gas valve as soon as the electrical contacts of the at least one pressure switch are opened. Further, the furnace controller operates the induced draft blower at or close to a lowest RPM at which the electrical contacts of the at least one pressure switch can be kept closed, which is between a make point RPM at which the electrical contacts of the at least one pressure switch close and a break point RPM at which the electrical contacts of the at least one pressure switch open.