We moved into this house this summer. Its an old farmhouse. For the last couple weeks, we have had frequent headaches and tiredness. We got a carbon monoxide detector and it isn't going off. The heat is fule oil and it seems to smell strnger than we think it should but we have never had it. The landlord came and looked at the furnace (which is old as dirt) and he says its fine, but of course he does, he wouldn't want to replace it... If the monoxide isn't the issue, does a fuel oil furnace put out other gases that could do this? Or any other suggestions?