Your home air conditioning system uses a lot of energy, especially during the summer. To try and save money on their cooling bills, some people close the registers and vents in unoccupied rooms. The assumption is that doing so decreases the amount of cold air allocated to rooms where it’s not needed, allowing the air conditioning system to work less. While the logic might seem sound, it’s actually incorrect. Closing you system’s air vents does not save you money. In the long run, it can actually lead to safety issues and costly repairs.
How AC Systems Work
Your heating, ventilation and air conditioning (HVAC) system is powered by an electric motor that blows air through the system. It pulls air from the house through return ducts and then pushes it back into the house via the vents. Each system is designed with a motor capable of blowing air against a maximum level of pressure. Excessive pressure forces the motor to adjust its power and output in order to maintain proper air flow.
When a homeowner closes the vents that blow air into the home, it’s forced back into the system. This puts additional pressure on the blowing motor. Over time, this building pressure can cause a number of problems for your home and HVAC system.
High-Pressure Risks
Air that backs up into the HVAC system’s motor isn’t content to just hang out until it’s blown into another room. The more vents you close, the higher the pressure builds. An electric motor will be forced to use more energy to control the flow of air. Once the pressure becomes too great, cool air will start leaking out of the duct system wherever it can. Most home ductwork isn’t perfectly sealed. The air escapes through small cracks in the ductwork, blowing into your attic or other spaces within the home, wasting energy that was intended to cool your living spaces.
A buildup of cold air can actually permanently damage your HVAC system. Cold air is created when uncooled air passes over cooling coils, which bring down the temperature. Too much cold air in one place can actually freeze the coils, causing the system to shut down.