Stuff Thermals Screwed Up

Our 1940's Colonial Revival has hot-water baseboard heaters. When we moved in a few years ago, the walls were pristine, but lately we’ve been plagued with ghosted jets of grime on the walls above the vent openings. It’s kind of creepy.

- Gene Leigh

​THE FIX

Your problem is a common one. It can happen whether the fuel source is gas or oil, and whether the heating system is a hot water boiler or a hot air furnace.

The ghostly stains, called thermal tracking, are actually deposits of soot or dust circulated in the air and deposited on the walls. They can also appear around electrical outlets and along studs or joists on the wall surface.