I had my brick chimney inspected, and the inspector found that the cracked clay tiles in the two flues (one for a gas fireplace, one for the furnace and gas water heater) need to be replaced. He recommended a flexible stainless steel liner for the utility flue at a cost of about $3,200. I also had an HVAC guy in to replace a crack in the water heater exhaust, who noticed some signs of condensation on the elbows of the furnace and water heater exhaust. He recommended instead that he "could put a 'CHIMNEY KIT' on the furnace and run double wall vent pipe to the chimney" for only about $900.
Obviously, I'd like to spend less, but I'm wary of taking shortcuts on the exhausting of gases from my house. Does anyone have any experience or thoughts on using a chimney kit into the chimney instead of relining the chimney for 3.5x as much?