Black Marks on Ceiling

[John Boy]

Tom Veno

I have in the past seen black marks that outlined the ceiling trusses and the wall studs in a attached heated garage. The problem was the natural gas heater had a cracked heat exchanger. The leak from that caused the soot to form on the trusses and studs. Get yourself a good Carbon

Monoxide dectector for your house. Have the furnace checked for a cracked heat exchanger. Perhaps the chimney is blocked, remove the chimney tee cleanout cover and look up your chimney, Is there combustion make up air available for the furnace or other gas burning appliances. Perhaps when to turn on the exhaust fans, kitchen range hood, clothes dryer, these appliances exhaust air and you have no other area for the intake air to come other than down the chimney.

Run some of your fans and light a match,blow it out and hold the extinguished match near the draft hood of the water heater (if gas) or the draft hood of the furnace. Does the smoke from the match blow away from the hood. A simple test. If it does then you negative draft. Try the same test only this time turn off the fans or clothes dryer and see if the smoke from the extinguished match goes up the draft hood connector of the furnace or gas water heater.

You may need to a combustion air vent for the gas appliances. You might need a Heat Recovery Ventilator.

You might have a plugged heat exchanger on the furnace. You might have a cracked heat exchanger.

You might have a blocked chimney.

These are some of problems you may encounter.

John Boy