Should You Turn Your Heat Off When You’re Not Home? What HVAC Pros Say

Finding the ideal temperature for your home can be an art form of sorts during the fall and winter, especially for those of us who like to save a few bucks. But completely turning off the heat, especially if you’re away for vacation or at work, may not be the best choice. In fact, experts say this method can have detrimental (even near-disastrous) results.

For the safest and smartest approach to saving energy (and money) during the colder months, we spoke with three heating and indoor air quality professionals. Their advice makes one thing very clear: Turning your heat completely off is rarely the way to go.

How to Handle Your Home's Heat When Away

HVAC professionals agreed that lowering the heat is almost always the move—both from an efficiency and safety perspective—versus turning the heat off completely. "While you do save energy by reducing the temperature, completely shutting off the system can lead to your home losing too much heat, says HVAC expert Brian White, "which could require a significant energy surge to reheat everything when you return."

White says setting the thermostat back 7-10 degrees is optimal, which is also the recommendation from the U.S Department of Energy. This will help provide your home's system with adequate air circulation and maintain even humidity.

Lisa Purvins, owner of Pro-Tech Heating and Cooling, compares it to driving on the interstate. "If you’re always braking hard to slow down, you'll end up burning more gas to get back up to speed," Purvins explains. "It’s more energy-efficient to gradually adjust your speed, and the same principle applies to your heating system. Shutting it off entirely is similar to a hard brake, whereas keeping it running at a modest temperature is more efficient by comparison."

3 Risks of Switching Off Your Heat Entirely

Turning down the thermostat is more energy efficient in the long run, but it’s also the safer option. Completely turning your heat off in the cold can have real (unfortunate) consequences. These include the following.

Frozen Pipes

This may be the most serious risk of turning off your heat off during the winter. “When temperatures drop below freezing, water inside your pipes can freeze and expand, often causing pipes to burst and resulting in costly water damage,” White explains. Purvins adds that this is especially a risk for homes with “exposed or poorly insulated plumbing.”

Mold and Moisture Build-Up

Turning off the heat completely can cause a surplus of moisture and condensation, which leads to mold and mildew growth. "When a home cools too much, indoor humidity can condense on windows, walls, and ceilings," Purvins explains. "Over time, this moisture can contribute to mold growth, wood rot, and damage to finishes or insulation. Homes that are tightly sealed and insulated are particularly prone because the air doesn’t circulate enough to dry out surfaces."

Shortened System Lifespan

Reheating a completely cold home is a tall task, especially for older furnaces and heat pumps. Purvins even says that this can “shorten the lifespan” of these components, since the “system has to work harder.” 

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Expert Tips for Saving Heat (and Money) All Winter

Whether you’re looking for tricks to save energy while at home or while on vacay, we have you covered. Below, see how the professionals keep their homes energy efficient through the winter.

When You're Home

• Keep the thermostat on 68-70 degrees, or less: White says that the lowest temperature that you’re comfortable with is best for saving money.
  
• Reverse your ceiling fans: This helps circulate warm air, White explains.
  
• Regularly change your HVAC filters: Fox explains that replacing your filters every 3-12 months (depending on the type of filter) prevents your system from overworking.
  
• Keep curtains open on south-facing windows: During sunny days, White says this will help add natural heat to your home. 
  
• Close vents or doors in unused rooms: This can help focus the heat in critical places.
  
• Make sure vents aren't blocked by furniture: This can interfere with proper airflow.

When You’re Not Home

• Set the thermostat to 50-55 degrees Fahrenheit: White says this prevents freezing but still minimizes energy use.
  
• Shut off your main water supply: This reduces the risk of plumbing disasters, especially if you'll be gone for weeks, White explains.
  
• Install a smart thermostat: These can reduce heating costs by 10-15 percent, according to White. Plus, they’re often controllable via app, allowing you to adjust the temperature as needed, even from afar.
  
• Ensure insulation and weatherproofing are solid: Especially for extended trips, Purvins notes that "heat lost to drafts will undermine any thermostat setback strategy."
• Leave cabinet doors under sinks open: This can help keep pipes warmer, Purvins explains.