Cleaning carpet stains around heat vents and baseboards

November 26th 2001

How do I get rid of the grey stains on the carpet around the edges of the heat vents and baseboards? We have a gas fired furnace - what causes this?

Stains around the heat registers and outside walls as well as inside walls and stairs cases are caused from air infiltration and exfiltration.

1. Homes with forced air furnaces will have stains around the heat registers as well as outside walls. Stains on the carpet on inside walls and stair cases are caused from positive air being pushed out under outside walls and your carpet becomes a filter picking up all the impurities in the air as it passes under the wall. (this shows up more on light coloured carpet) To clean use Pink Solution available through Earth Care Sales call 1-800-565-9972 to locate store that carries product in your area. Now caulk the area the air is coming through ie; where the wall and the floors meet, this will seal the problem once and for all.

2. Some houses with forced air furnaces will have stains on carpet around heat register floor vents caused from air being pushed around the register when register is closed. (keep in mind a register louver is for directing the air flow not to shut off or turn on) Also stains found in areas of stair cases or stair wells and inside walls indicate cold return to the furnace is short cutting ways to get to the furnace blower thus pulling air under the walls and around stair treads to cold air duct running under the floor joist in the basement.

3. Electric, Hot water, Radiant or Convection heated homes can have similar stain show up but always on the outside walls. This is caused by air leakage from the home (windows & doors etc.) Range hood fans, bath-room fans exhausting air out of the home and make up air or infiltration air coming in under the outside walls thus staining light coloured flooring.