There are two reasons combustion gases may not be drafting out of the home through the flue: backdraft or blockage. Backdraft can happen when the furnace is not properly ventilated - meaning it is not getting enough air required for combustion. When a furnace doesn't get enough oxygen from the air, it will draw air back down from the flue, preventing exhaust gases from escaping.
What are the signs that a furnace is not ventilating properly?Because exhaust fumes are moist, one common sign of exhaust venting indoors is condensation on windows. In addition, when the moist fumes backdraft the metal front of the furnace may show signs of corrosion. In some cases, you may also notice a sour smell in the home.
If you suspect there is a ventilation a problem, have the furnace serviced as soon as possible. Ostrom can diagnose any potential problems quickly and perform any necessary repairs to keep the furnace operating safely.