A persistent home heating myth holds that shutting a room to conserve energy while heating or cooling a whole home is a good idea, because you are heating less volume. It is not true in most cases, and there are better ways to save energy and money.The System
Your home’s furnace and ductwork run efficiently as a whole system only when circulating the volume of air your furnace was designed to heat. (The same applies with cooling, as well.) Warm air goes out to all the rooms of your home from the furnace through air supply ducts and comes back for reheating by return air ducts fromall the rooms.
Air Will Find a Way
Shutting a room off does not stop air flow. The return register in a closed-off room will still pull air from the room, creating a pressure imbalance that will cause cold outside air to rush into the room through gaps and cracks in windows and doors. The room temperature drops and the closed room draws heat energy from adjoining rooms by conduction through uninsulated interior walls. To compensate for this heat loss, your furnace overcompensates, eating up more fuel.
Consider, too, that shutting a room to conserve energy reduces the volume of efficiently moving air without reducing the size of your furnace. Your furnace will start and stop often to heat the smaller volume. That’s called short cycling, and it eats up fuel and money, while stressing parts and leading to premature breakdowns.
The closed supply vent also makes air pressure rise in the supply ducts, straining seams and loose connections in ductwork. This will create leaks or make small existing leaks larger. The air you have paid to warm may even escape into useless places – basement, attic and floor spaces. On cold days, ducts may actually freeze; then your furnace has to work even harder.
- Instead of shutting a room to conserve energy, have a professional HVAC technician adjust ducts and vents while still balancing air flow. Or partially close vents in unused rooms in order to reroute warm air to where it’s needed.
- Keep ducts clean and sealed for efficient air flow.
- Install a programmable thermostat
- Upgrade to a modern, high efficiency heating system
Our goal is to help educate our customers in Overland Park, Kansas about energy and home comfort issues (specific to HVAC systems).
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