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Will Closing Vents in Unused Rooms Boost HVAC Efficiency?

July 15, 2019

It’s common to have some rooms in your home that always get too hot in the summer or too cold in the winter.  In an effort to force more air into the needed room(s), you close some vents in the little-used rooms. This may seem like a good idea, but you may be doing more harm than good when you seal up or block vents.

When you close a vent register, the system keeps cooling and pumping without delivering the cool air to a usable space. You’re basically paying to keep the inside of your ductwork cold!  In fact, this may lead to increased energy consumption due to increased duct leakage of conditioned air, and increased suction of unconditioned air from around doors and windows.  If the return air grate for your home is located in or near the closed off room, then you’ve really created a problem!  This can cause the compressor and condenser to cycle too frequently, and puts strain on the whole system, leading to accelerated wear and ultimately, an early failure. Plus, with the added pressure against the closed vent, it is apt to start “whistling” or making a rattling noise.  Why risk this damage when it doesn’t work and won’t even save energy?


If you only want to keep a single room cooler or warmer, consider adding a ductless mini-split system, or adding an additional register or enlarging the existing registers in that room. Checkout our posts about uneven heating and cooling and our 3-part video series on zoning for other possible solutions.  But the best thing would be to have a skilled HVAC technician evaluate your problem, so you’ll have confidence that the solution they propose will work… instead of spending money on things that may not.

If you live in the Nashville area and want to make sure your air-conditioning or heating system is running at peak efficiency, call on Interstate AC Service, at (615) 832-8500.  We’re here for YOU!