Shutting a room vent in an unused room may make you feel like you’re saving energy. However, it’s more feeling than fact. The truth is, your HVAC ductwork system is designed and constructed to provide a precise volume of airflow to all rooms through supply vents and return the same volume of air through return vents. Shutting a room vent upsets that carefully calculated balance, causing a domino effect that results in higher energy costs and less consistent heating throughout the house. Here are some of the downsides of shutting a room vent:
- Reduced furnace air flow.The cubic feet per minute of air passing through the furnace heat exchanger must meet certain minimum specifications. Closing a vent in a room subtracts from the total amount of air volume returning to the furnace. When airflow through the heat exchanger drops below specifications, the heat exchanger may overheat and crack. This can actually be dangerous as a cracked heat exchanger can allow dangerous carbon monoxide to infiltrate the house.
- Poor heating distribution.The diameter of ductwork in your home and the output of the system blower are are carefully matched to circulate an equal volume of air into and out of every room with an air vent, no matter where it’s located. If one or more vents in the system are shut, however, the balance shifts and rooms furthest away will be chronically under-heated. Turning up the thermostat to make them comfortable increases energy consumption and, in turn, makes rooms closest to the furnace uncomfortably hot.
- More duct leakage.In most homes, aging ducts typically leak conditioned air into spaces like the attic, crawl space or the interior of walls. This leakage means higher energy costs, too, as the furnace or A/C has to run longer cycles to make up for the air loss and monthly bills rise. Shutting a room vent increases air pressure in leaky ductwork which, in turn, increases the rate of leakage.
Ask the professionals at Valley Heating, Cooling, Electrical for better alternatives to save energy that shutting a room vent.
Our goal is to help educate our customers in the South Bay Peninsula and Santa Cruz areas of California about energy and home comfort issues (specific to HVAC systems).