Just got the bad news that the 100+ y/o unlined brick chimney that vents my furnace & water heater (both nat'l gas) cannot be 'lined' with one of those flex liners, for fear of collapse. Short of paying $$$ for this rebuilding, what are my options? Anyone been there? Can I not use the chimney and use gas vent pipe? Where to run it, over to an outside wall, create a fake chase, and go up? We're talking a two story frame home here, in a near Chicago suburb. Who do I call about this type of project? Any suggestions, ideas, prayers?