As time is soon approaching to fire up the forced-air furnace, I close the vents to seldom lived-in areas such as the bedrooms, baths and utility rooms. Is this the most economical approach?
— Phil A., Eagle Point
Not so fast, Phil. You might be full of hot air.
Closing vents in seldom-used rooms actually can be very inefficient, according to a representative from Southern Oregon Heating and Air.
Forced-air systems are designed to run at a certain capacity based on the size of a house or building, and closing off part of the system by shutting vents could strain the rest of the air system.
"You could overheat the equipment," said Warren Carr, a service technician and salesman for the company.
Carr said that if you have a properly designed duct system, closing vents doesn't really make sense, and wouldn't save you any energy.
"I wouldn't recommend just closing them," said Carr. "You really have to be careful."
A 2003 study of California homes by the Lawrence Berkeley National Laboratory supports Carr's recommendation. The study showed that energy usage actually increased when vents were closed and portions of the houses were not heated or cooled. Much of that was attributed to increased duct leakage as a result of the added pressure placed on the system when fewer vents were available.
In addition to leaving vents open throughout the house, Carr said, leaving the system's fan on also is a safe bet.
The fan can even out pockets of cold and warm air, and keep the space more comfortable.
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