At 18:49 hours, F53 and 1421 (Nancy Run Fire Co) were alerted for a reported Commercial Building Fire on Mikron Rd in Lower Nazareth Nazareth Township. 5351(Chief Seip) arrived to find smoke coming from a vent in the area of the furnace. 5311 arrived and crew investigated the interior confirming the furnace malfunction. 1421 arrived and crew checked the roof. Companies cleared at 19:24.