At approximately 0350 hours, Engine 41 along with units from Columbia Borough Fire Department 80 were due to respond for a reported apartment building at the Trinity House Apartments in Columbia Borough, Lancaster County. The Wagon marked up with 7 men in two minutes. Arriving after Truck 801, the Wagon hooked up to the FDC (Fire Department Connection) and sent its manpower to the sixth floor where the fire was reported. Engine 804 arrived and laid a supply line into the Wagon. Crews from 41 made it into the sixth floor of the high rise and encountered a heavy smoke condition with no evacuation. Wagon 41's lineman and backup man made the standpipe connection and stretched to into the 6th floor. The rest of the crew assisted occupants from the sixth floor and into the stairwell. Engine 804's crew met with the crew from 41 and assisted with searching for the source of the smoke. Ladder 801's crew also operated and assisted occupants from the fifth, sixth, and seventh floors. The source of the smoke was determined to be from a malfunctioning heater in an apartment on the sixth floor. Companies operated for about an hour and a half.