THAW CYCLE IN CONDENSING STYLE GAS FURNACES

摘要

A condensing gas furnace having an inducer for drawing exhaust produced by a burner through an exhaust path and venting the exhaust from the furnace. A pressure sensor positioned within the exhaust path to determine if the inducer is creating a negative pressure in the exhaust path preventing accumulation of exhaust within the exhaust path. The inducer includes a supplemental sensor for monitoring rotation of a fan of the inducer. The burner is not ignited when both sensors fail to indicate proper venting of the exhaust path. The burner is operated for a predetermined period of time when only the supplemental sensor signals rotation of the fan to thaw any condensate on the supplemental sensor.

主权项

1. A gas furnace, comprising:
a burner operable to produce an exhaust containing products of combustion; an exhaust path for receiving exhaust from the burner; a primary heat exchanger having an inlet operably connected to the exhaust path and an outlet operably connected to the exhaust path, wherein the primary heat exchanger is operably receive exhaust from the exhaust path and return exhaust to the exhaust path; a working fluid stream operably connected to the primary heat exchanger to receive heat from the exhaust received within the primary heat exchanger; an inducer, including a fan, operable to exhaust the products of combustion through the exhaust path; a pressure sensor configured to measure pressure within the exhaust path and generate a pressure sensor signal; a supplemental sensor configured to detect rotation of the fan and generate a detection signal indicating rotation of the fan; a controller communicatively connected to the burner, the inducer, the pressure sensor, and the supplemental sensor, the controller being configured to:
rotate the fan of the inducer,receive the detection signal from supplemental sensor,operate burner upon receiving the detection signal from the supplemental sensor, andextinguish the burner if the pressure sensor signal is not received within a predetermined burn time.