I have an older house (1920) and I have been planning on doing some rewiring to get rid of some k + t stuff. Anyway, I just noticed today that there are some irons pipes that used to be part of the heating system. (they are no longer connected + filled with air). Better yet, they run in a perfect vertical run from the basement (where the panel is) all the way up to the attic (where the k + t to be replaced is).
Would it be improper, or otherwise unsafe to just repurpose these unused pipes as electrical conduit ??