How to Balance Central Heat Ducts

Open every heat vent completely in every room in the house. When you leave the rooms that have vents, leave the doors wide open.

Set the central heat thermostat to a temperature so the furnace kicks on and remains on until you are done balancing the heat ducts.

Wait for the furnace to warm the entire house up. How long that will take depends on factors such as the inside temperature, the size of the house, and the temperature outside.

Walk through the house and visit each room that has a central heat vent in it. Stop and feel the temperature in each room. Partially close the vents in the rooms that feel too warm. This will reduce the heat in these rooms and send more heat to cooler rooms in the house.

Set the central heat thermostat back to the usual temperature setting once you're done balancing the heating system.