Why You Might Need To Balance Airflow
If you're getting condensation in just one or two rooms, but the rest of the house is clear - you can adjust the vents to allow more airflow in the rooms that need it.
Which Vents to Adjust
Any rooms that are still experiencing condensation should have their vents opened wider. You can also close up the vents in rooms which aren't getting condensation - this can help force airflow into the rooms that need it more.
How to Adjust Vents
The centre portion of the vents can be rotated to close or open up the gap allowing airflow through. To open a vent up more - rotate the centre portion counter-clockwise. To close the vent up, rotate it clockwise.