About this Project

If some rooms in your home are consistently too hot or cold, don't blame the furnace. Instead, take on a simple "balancing" project.

To balance a forced-air system, you reduce the airflow to a room that is too warm. Warm air then reaches colder areas, typically those farthest from the furnace.

You already may have tried balancing by partially or totally closing registers in the hotter rooms. This cools the room off, but it doesn't redirect the air. Instead, look for dampers in the ductwork. Dampers are controlled by a handle or a locknut arrangement (see next page). You may find one at the point where each duct takes off from the furnace plenum. Not all duct systems have dampers, so consider installing some.

Identify which ducts serve each room, and label their dampers. Close them one at a time to determine which room isn't getting air.

Wait for a cold day to begin the balancing procedure shown on the next page. If only one or two rooms have airflow problems, you might be tempted to adjust only the dampers. Because balancing is a robbing-Peter-to-pay-Paul proposition, however, you'll get better results by tuning the entire system.