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With the high cost of heating and cooling a home, you may think that closing vents in some rooms will redirect hot air to the rooms with open vents. Unfortunately, it doesn’t work that way. An HVAC unit (furnace, AC, or heat pump) is sized specifically to match the cubic feet of rooms and a home’s overall living space, says JT Holt, instructional designer for Heating Air-Conditioning & Refrigeration Distributors International ( HARDI ).

What this means is that no matter how many of the unit’s vents are open, the heater will run at the same power level. Here’s why closing vents could end up costing you more than keeping them open.

Closed vents create duct pressure—and potential problems.

Photo: Charles Knowles via Shutterstock

HVAC systems consist of a series of metal ductwork and vents. Supply vents deliver heated (or cooled) air to rooms from the HVAC unit.…