By Dwight Barnett
Scripps Howard News Service
Q: Could you please explain the process that heating technicians perform to clean or, as they say, sanitize your ductwork? Is this a process a handy homeowner could perform himself? I hate the smell when you first put on the furnace in the fall, so I'd appreciate your advice.
--D.F., Chicago
A: The odor you sense the first time a warm-air furnace starts up in the fall is toasted dust and dirt that have collected on the heat exchanger.
Simply stated, the heat exchanger is the metal housing inside the furnace where the burners are located. The burners heat the inside of the metal, which in turn heats the air that passes over the exterior of the metal. When the furnace is not in use for long periods of time, the metal becomes cool, which attracts moisture. The dust and dirt that are present in the air collect on the damp metal waiting to be burned off the next time the furnace is used.
Cleaning the ducts may or may not clean the heat exchanger. But duct cleaning is not a do-it-yourself project. The cleaning equipment is expensive and difficult to use; though basically it is a large truck-mounted vacuum cleaner.
Q: I have the spalling problem on my brick chimney, mostly near the top. A recent article you wrote concerned a lightweight stone and brick that can be glued to a wood-framed chimney. I take this to mean that you attach a wood frame to the chimney and then glue this veneer to it. --R.C., Hendersonville, Tenn.
A: The article you refer to was concerning a chimney that was falling apart and endangering the occupants of the home. Spalling brick is not a danger unless a piece hits you on the head. The chances of that happening are infinitesimal.
If a brick chimney that serves a fireplace has to be removed, it should be replaced with another brick chimney. If the chimney serves a furnace or water heater, it can be replaced with a wood-frame chimney that has a metal flue liner. Then the wood frame can have any exterior covering that meets your needs and decor.
DO NOT attach a wood frame to a brick chimney. Hot ashes and flue gases could escape the flue through the damaged brick and start a fire in the wood frame.
Contact a masonry contractor to replace the damaged brick on your chimney. If you can't match the existing brick, you could choose to either leave the spalling brick as is or use a different shade of brick.
(C. Dwight Barnett is a master inspector certified by the American Society of Home Inspectors. Questions may be addressed to him at PO Box 14091, Evansville, IN 47728, or e-mail dbarbett@evansville.net .)
