Closing air vents in unoccupied rooms to save money sounds like a no-brainer. The theory is that simply shutting vents in empty rooms during winter makes your furnace run less and thus reduces monthly heating costs. Like many theories that sound too good to be true, however, the scientific facts say otherwise. Closing air vents can actually reduce energy efficiency as well as disrupt the proper distribution of heating throughout the entire house. Here are a few reasons why:

The Facts About Closing Air Vents

  • The furnace doesn’t know that some vents are closed. Your furnace keeps producing the same volume of hot air at the same temperature whether all vents in the house are wide open or some rooms are deprived of heat entirely. Until the thermostat setting is reached and the system cycles off, the furnace continues to consume the same amount of energy as long as it’s running.
  • Closing vents unbalances the system. Your furnace and ductwork are designed to work together as a matched system. Furnace output is calculated to match the specific diameter and extent of the ductwork in order to ensure that every room — including those furthest from the furnace — receives an equal volume of circulating hot air. Closing air vents in certain rooms while leaving them open elsewhere upsets that critical balance. Rooms closest to the furnace may become overly hot while rooms further away will stay chronically chilly. Also, the increased pressure in parts of the system caused by closing vents may exacerbate heat loss through small duct leaks that are present in any system.
  • Cold rooms in a warm house act like a heat sink. It’s a fact of physics: Heat is naturally drawn out of warm areas into colder zones. Keeping one or more rooms unheated inside an otherwise warm house tends to suck heat energy out of the heated areas and into the cold rooms through uninsulated interior walls. The furnace cycles on and off more frequently to compensate for the heat loss, actually raising energy costs and diminishing indoor comfort.

For proven energy-saving ideas, contact the heating experts at Apollo Home Heating, Cooling, Electrical and Plumbing.