Why the liner matters
Your furnace and water heater send their exhaust up the chimney through the flue. The flue has to be the right size for the appliance: too big and the exhaust cools, condenses and drafts poorly, too small and it cannot carry the exhaust away. A flue that worked fine for an old appliance can be the wrong size for the new one.
When to check
When you replace a furnace or water heater that vents into the chimney, when one of two appliances sharing a flue is removed or changed, or when the installer tells you the flue needs attention. Ask your installer how the new unit vents. Some newer high efficiency furnaces vent out the side of the house with plastic pipe and no longer use the chimney at all, which can leave a water heater alone in a flue that is now oversized.
Warning signs of a flue problem
Water or white staining near the base of the chimney or the appliance connection, rust on the flue pipe, crumbling tile at the cleanout, a damp or sour smell in the basement near the chimney, or the appliance shutting off because of venting problems.
What a liner costs
Our liner installs start at $2,000. Furnace, water heater and boiler liners usually run $2,400 to $4,500 depending on the height of the chimney, the liner size and how many appliances share it. We inspect first and show you photos of the flue. See chimney liner installation.