I just did a wierd test.
The Observatory is covered in dew, the scopes are covered in dew, so I breathed on the lenses of both the ED80 and the guidescope!!!
The breath fog evaporated immediately!!!!!!!!!!!!!!!!!
I felt the heater strips and I can barely feel anything at all. The heater strips must only be the required 1 or 2 degrees above ambient!
What a fluke