I seem to recall a product for de-icing gutters. It was a tape/cable that ran underneath the gutters, was held by adhesve, and did not enter the roof line. The idea of the product was to allow a free flow of water through the gutters by heating from the bottom, giving a channel. If memory serves, it could also be wrpped around or run down the back of the downspouts to keep them free from ice as well.
All I see available now are the cables that zig-zag across the bottom foot or so of the roof, and apparently into the gutter as well. I assume that these are probably better for the purpose of preventing ice dams, which is my objective, but I don't want to attach anything to my roof, even with adhesive.
So, my questions: Are the under gutter tapes available (or were they perhaps a figment of my imagination)? If they are available, are they effective in preventing ice dams? Are the zig-zag tapes better? Is there a way to attach the zig-zag tapes to the roof without adhesives, tacks or nails? I saw clips advertised, but I wonder about their effectiveness.