Operating a clothes dryer that is un-vented creates lots of condensation in the house. We are waiting for our laundry area to be renovated and needed to vent the dryer to the exterior whilst keeping the heat from escaping from the house (it's winter now)

Step 1: Attaching Vent Duct

1. Measure external diameter of vent orifice in the front (or back) of dryer
2. Buy a duct hose from hardware store of the same diameter
3. Cut a hole in a piece of cardboard or styrofoam at least a centimeter thick, orientating the hole to the orifice on the front of the machine. Make two pieces of this.
4. Attach the boards to either ends of the duct
5. On the Machine end, attach lightly but securely with Blu-tac in each corner. It is important not to have an air tight seal as this is not a purpose built solution and may void the gaurantee of your machine
6. Lead the other end out of the door

Step 2: Venting to Exterior

Lead the other end of the duct to the exterior of the building - in this case through the patio door. Close the curtains to prevent heat from escaping the house.
I later moved the dryer to the stack on top of the washer and lead the duct through a small window that I could completely close off with a styrofoam board, thus ensuring better partition of room and outside air, and thus less moisture and condensation in the house when the dryer was being used.