On Wed, 5 Oct 2011 08:30:38 -0700 (PDT), millinghill
wrote:

Jumpering the 'stat with a switch may be the easiest.-

Agreed, but then I'd need two wall switches. Ughh.

You can get two toggle switches that fit in a single box. That's what
I have for my roof fan.

I can turn it off when the stat would turn it on, or on when the stat
would turn it off. I use both features. Normally, when I'm using
neither feature, one of the swtiches is Off and one is On so that the
stat controls things. Eventually I got confused which position was
normal, so I drew a line with an indelible marker across both toggles
in their nomarl position.

You would need three conductors from the swtich to the fan/thermostat.

If you're using BX and there's enough room for one more conductor, you
could solder one of the conductors that is in there to two new ones,
and pull the two through the BX that way. In my house, it's about 8
feet with only a small bit of bending, but be sure to allow a few
feeet extra so you don't pull the wires into the BX. Or have a
helper or better yet tie a big knot in the wires.

If romex is legal where you are, and the BX isn't stapled inside the
wall, you could solder the romex to the BX wires and pull the whole
thing through.