Shared from Mikes Heating & Cooling.

Many people think that closing vents to unused rooms will save energy, however before you do that, you should be aware of potential issues it might cause and check with your HVAC professional.

When you close the vents in your home the first thing that happens is the air pressure in the duct system increases, which may give rise to these negative consequences:

  • Increased duct leakage
  • Lower air flow with PSC blowers
  • Increased energy use with ECM blowers
  • Comfort problems because of low air flow
  • Frozen air conditioner coil
  • Dead compressor
  • Cracked heat exchanger, with the potential for getting carbon monoxide in your home
  • Increased infiltration/exfiltration due to unbalanced leakage , as I described last week
  • Condensation and mold growth in winter due to lower surface temperatures in rooms with closed vents

You’re not guaranteed to get all the problems that apply to your system, but why take the chance.

Source: 9 Unintended Consequences of Closing Vents