Why Closing Vents Seems to Make Sense
If you’re not using a spare bedroom why not close the vent, save money, and redirect the heat to the other rooms? Most furnace registers (vents) even have a built-in lever that allows you to adjust the louvres behind the grille, change the direction of the airflow, or shut off the airflow altogether.
What Actually Happens When You Close Vents
Closing vents and closing doors doesn’t prevent air movement, it just interferes with it. The closed-off room will be under pressure and if it has a return air duct it will pull in cold air from leaks around windows. The warm air trying to push up through the closed vent will create pressure as it backs up and it may leak out of ducts that are not sealed properly or force an opening in the ductwork, leaking warm air into the floor cavity or back down into the basement.
Meanwhile, your furnace will continue trying to push air to all the vents. Newer high-efficiency furnaces will detect the increased air pressure, step up the fan speed and attempt to push through that pressure (and lessen their efficiency). Older furnaces will continue running like normal but operating under this increased pressure will strain and wear the furnace motor. The pressure can damage the ductwork or, worse still if the pressure gets high enough it will damage the furnace.
Your furnace depends on good air flow to operate properly. If it does not have enough air being returned to it and then taking the heat away from it, the heat exchanger could crack and this would result in carbon monoxide leaking into your home, circulating through your vents. In addition to the huge health risk, your furnace would also need to be replaced.
Conclusion
It’s not a good idea to close vents, but if you’re determined to shut off the heat to a room, contact an HVAC technician from your preferred home services company. They will tell you what can be done safely and what adjustments can be made to the operation of your furnace. Alterations you make on your own won’t be covered under the warranty of your HVAC system and could cause serious damage to your HVAC system. A professional technician will ensure that your furnace is working well. Oftentimes an HVAC technician can help you get your furnace operating more efficiently (and saving you money) in ways that do not involve closing vents.
