We Asked HVAC Experts If You Should Really Leave the Heater On All Night—Here’s the Verdict

You may be tempted to run a heater to ensure it’s nice and toasty, but should you leave a heater on all night? The answer depends on the type of heater you’re using. Some home heating sources are designed to run continuously throughout the night, while others should only be operated for short periods and never left unattended.

Below, we’ve explained whether you should leave your heater on all night and talked to some HVAC pros about proper heater usage and ways to stay warm at night.

Should You Leave Your Heater on All Night?

You shouldn’t leave a portable heater on all night. While there’s always a low-level fire risk associated with space heaters, that risk is multiplied overnight, as you’re sleeping and unaware of your surroundings, Robert Hamerly, the principal and CEO at GreenSavers, says.

Hamerly recommends shutting them off right before getting into bed, then making sure you have plenty of layers on the bed to hold the heat.

“The thing is, portable heaters can work for supplementing heat in a drafty room, or a room with no vents from a ducted system (like an addition or a home office in a garage), but they’re typically not designed to run all night,” Hamerly explains.

Portable heaters can overheat if they run too long and are always at risk of falling over, so it’s best only to run them while you’re watching and aware.

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Use Your HVAC System Instead

Many people try to save money on utilities by turning their thermostat down (or even off) at night, and then using space heaters in whichever room they are sleeping in, but this doesn’t usually work out how they expect.

Instead, you should leave your HVAC system on all night to maintain a consistent temperature in your house. In fact, turning your heat off at night can even overwork your system and lead to a higher utility bill.

“Many HVAC systems and smart thermostats can be programmed to dip slightly overnight, but I wouldn’t fluctuate more than 2-3 degrees to avoid condensation caused by indoor temperature changes,” Hamerly explains. “Choosing this method is the surest way to avoid overworking your system, and to avoid the aforementioned condensation, which can lead to dampness and mold.”

The Temperature You Should Set Your Thermostat to At Night

During waking hours and while you’re at home, Bill Taylor, an HVAC contractor manager at South Jersey Gas & Elizabethtown Gas, suggests setting your thermostat to 68°F to conserve energy. This temperature will strike the best balance of comfort and energy conservation.

Given Hamerly’s guidance of only dropping your thermostat by a maximum of 3 degrees at night, if you drop your home’s temperature below 65°F at night, you risk overworking your system and causing condensation issues.

What to Do Instead to Stay Warm at Night

If you’re finding that turning off your heater at night is making your bedroom too cold, here are some alternative ways to stay warm at night.

• Run the portable heater right before bedtime. Instead of running the heater all night while you’re asleep and unaware, simply use it before you get into bed to heat the room.
• Use lots of layers. Piling on lots of cozy layers on your bed will help to prevent your body heat from escaping, keeping you warmer through the night.
• Open the door. If your space lacks a vent or is particularly drafty, it can be helpful to open the door, which allows the heat from your furnace to circulate throughout the space.
• Improve your HVAC system. If you’re using a portable heater to supplement your HVAC system, it may be time to upgrade your system. Whether that means upgrading your entire unit or simply adding ductwork to reach your bedroom, HVAC units are designed to run as long as it takes to keep your space comfortable.
• Install a smart thermostat. Taylor advocates for the use of smart thermostats to get the most out of your unit with minimal energy waste.

“With different control mechanisms, room-specific settings, and adaptable timers, smart thermostats can control the amount of energy you’re using,” Taylor explains. “Once the setup is complete, it requires little maintenance, which is a win/win overall.”

Taylor also recommends purchasing a smart thermostat through your energy supplier since it may be discounted.