Don’t Close Air Vents

In an effort to save more money by using less energy, many people close their air vents in rooms that get little or no use. However, instead of saving money, it could cause some serious issues. Read on to learn why closing vents does not have the desired effect on air distribution.

The blower in the HVAC system pulls air from the house through the return ducts, cools it, and pushes it back out through the supply ducts. The blower in high-efficiency HVAC systems is powered by an electronically commutated motor, also referred to as an ECM. This type of motor can adjust its speed. Those that are not high-efficiency are permanent split capacitor or PSC powered, which cannot adjust speeds.

Both systems are designed so that the blower pushes against some maximum pressure difference. If the filter is dirty or the supply ducts are restricted, the blower has to push against a higher pressure.

In the ECM system, this will make the motor increase in intensity to maintain proper air flow. As it works against the higher pressure, all efficiency is lost. A PSC motor will keep spinning, but its speed will decrease as the pressure increases.

When air ducts are closed in some rooms, the system becomes more restrictive. A higher pressure in the system will either ramp up the ECM blower, or move less air with a PSC blower, while also creating duct leakage.

This can also have an impact on the coil or heat exchanger. Lower airflow means a lower rate of heat exchange will occur. This will cause less heat to flow over the coil, making it colder, and possibly freezing. The refrigerant may not properly evaporate either, meaning it would come back into the compressor,  possibly ruining it.

In summary, here are 5 problems that can come from closing air vents:

  • Duct Leakage
  • Lower Air Flow/Increased Energy Use
  • Comfort Issues
  • Frozen Coil
  • Dead Compressor

Don’t close vents to save money. Instead, use an adjustable thermostat and be mindful of the energy being used.

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