Are you currently in Alberta? If you have that much moisture then I'm guessing that you're living in a cold climate running the heater. If that is the case then try doing this.
Get a four inch section of 1.5inch pvc pipe. You'll also need some sort of a 14x14 sponge to put into the roof vent. Open the roof vent about an inch, place the pipe in a corner, then jam the sponge rubber into the vent. That small opening will vent out the humidity, but still keep most the heat inside.
If you're not heating in a cold climate, then I'm betting you have a roof leak somewhere.