Why not close air vents in rooms that aren’t occupied? After all, closing a vent diverts heated air to other occupied rooms that really need it, so what can go wrong?

It’s sort of like the urban legend that quickly sticking a wet cellphone into a bag of uncooked rice dries the phone faster and prevents damage. This sounds good, but controlled scientific experiments indicate that rice doesn’t work any better than simply letting the phone dry in open air.  Likewise, many notions about the benefits of closing air vents in rooms don’t pass an up-close examination either. Here are a few reasons why.

• It doesn’t save energy. Your furnace doesn’t “know” whether a particular room vent in the house is shut or not. When the furnace cycles on, it simply continues producing the same volume of heated air — and consuming the same amount of energy — until the system thermostat shuts the unit off. Closed vents don’t reduce costs.
• Airflow is unbalanced. Balanced airflow in the system ensures every room receives the correct volume of heated air for the square footage of the room. Closing the vent in one or more rooms, however, disrupts the airflow balance and can make certain rooms overly hot while others are too chilly.
• The pressure mounts. The system blower keeps circulating the same amount of air at all times when the furnace cycles on. Closing vents in one or more rooms means that air pressure inside the ductwork mounts. This can increase the loss of heated and cooled air through ductwork leaks.
• Sizing matters. A furnace and air conditioner produce a specific output of heating or cooling to match the square footage of a home, as well as other specific factors in the dwelling. Closing off a room vent, however, is equivalent to making the house smaller. This means the HVAC components are now oversized. An oversized furnace or AC continuously cycles on and off rapidly, making indoor comfort less consistent, increasing wear and tear on the units, and raising utility costs.

For all your heating and air needs, talk to the HVAC professionals at Jackson & Sons.