Don't Close the Vents: Effective Temperature ControlWe can understand why some homeowners think closing vents and registers is an acceptable way to control indoor temperature. Bedroom too cold? Sure, close the vents and keep the cold air out. Not only are you warmer, but you’re saving money by not air conditioning that room. Right? Wrong. In fact, closing vents can actually cost you more on your utility bills, and may even damage your HVAC system.

Here’s how it works.

Why Closing Vents and Registers Is Not Efficient

Your HVAC system is designed to deliver a certain volume of air via the ductwork and through supply vents — the ones you feel the cold or warm air emitting from. When air travels through ducts to a closed vent, a pressure imbalance results. The air has to go somewhere, so may be forced through leaky areas of the ductwork, or into a basement or floor cavity — all uninhabited spaces where the conditioned air will be wasted.

The return registers in the room will also be affected by this pressure imbalance. The system will attempt to draw in air for heating or cooling, but the pressure imbalance will result in unconditioned air being pulled through minute cracks around doors, windows or wherever.

Blocking vents and registers causes your HVAC system to work harder, not only to produce proper air flow, but to heat or cool the air. As with any appliance, extra wear and tear can lead to breakdowns. Other problems that blocked vents and registers can cause:

  • Failure to heat or cool the home properly
  • Frozen air conditioner coil
  • Damaged compressor
  • Cracked heat exchanger (which can result in leaking carbon monoxide)
  • Mold and condensation from lower surface temperatures

Instead of Blocking Vents, Do This

If you really want to block air flow to certain rooms, ask your HVAC consultant about a zoned system. Zoning allows the operator to select temperatures by means of individual thermostats, which then open or close dampers in the vents in each of the zones.

For more on controlling indoor temperature or to schedule repairs, maintenance or equipment installations, contact Mowery Heating, Cooling and Plumbing.

Our goal is to help educate our customers in Brownsburg, Indiana and surrounding areas about energy and home comfort issues (specific to HVAC systems).