Performed heating maintenance on a Trane single stage 80% efficient natural gas furnace Cleaned flame sensor 20x25x1 Filter is in good condition Blower is clean Removed blower and cut open the return to the filter rack to allow for maximum airflow across the filter Run tested furnace Gas pressure set to 3.5"wc Adjusted blower speed from 6 down to 4 Temperature rise 47⁰ (spec 30-60⁰) Flue pipe in good shape Furnace is operating within factory specs at this time