my house was built on 1948. our heater and hot water heater (all the same unit) is run with oil fuel, and we have radiators. the heater is probably almost as old as the house. we have had the heater serviced every year since we bought the house, unfortunately we still are noticing soot on the walls, on any white plastic in the house, etc. could you tell me what could be causing all of this soot, is this harmful to my family, and are there any recommendations on solving this problem. thank you!