What is this brown stain around the heat vent in a 1970's home that I recently acquired? Is it rust? This is on a lino floor. It doesn't have a significantly different texture from the surrounding linoleum. The lino doesn't seem any more brittle or damp or slimy where the stain is. It just seems to be discolored. Is it due to the heat? Is it benign? What is the best way to fix it?

It seems to have happened wherever there is a heat vent on lino. This is by far the worst case in the whole house. the others are much more subtle.

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  • 1
    Does the house have AC? It could be condensation rusting the backside of the vent – Jack Dec 6 '16 at 7:34
  • Do you have an in humidification system in your furnace? – mikes Dec 6 '16 at 11:13
  • If you remove the vent, do you find any rust or discoloration on it? – Daniel Griscom Dec 6 '16 at 11:53
  • I wonder if it has something to do with the adhesive getting warm and wicking into the linoleum. Are you sure it's a brand new discoloration, and not just emphasized by recent cleaning? – BrownRedHawk Dec 6 '16 at 12:58
  • I have seen this in the past, It was caused by the register rusting + Jack. – Ed Beal Dec 6 '16 at 14:45

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