How to Use Your Fireplace Efficiently Without Wasting Energy
Enjoying a cup of tea by a warm fire sounds like heaven on cold winter nights, but should you turn off your home's central heating while the fireplace is lit? It might seem like a common-sense answer-after all, why would you waste energy if the fireplace is doing the work-but it turns out, it's not so simple. Our HVAC experts weigh the pros and cons of turning off the central heat while using your fireplace, along with best practices for homes that use both sources of heat.
Why You Should Leave Your Heater On
Turning your heater off when the fireplace is on may seem like a smart way to conserve energy, but our HVAC experts say this does more harm than good.
Avoids Uneven Heat
The main reason for leaving your heater on when burning a fire is that fireplaces create uneven heat. This means the room where the fire is burning stays warm while bedrooms, bathrooms, and upstairs rooms get chilly. The only instance when this isn't the case is in small homes where the fireplace can heat the entire house, says Josh Mitchell, HVAC technician and owner of Air Conditioner Lab.
Reduces Energy Usage
Furnaces are designed to exchange all the air in the home. "When the heating system is off during the use of the fireplace, the system will later have to be turned back on and work that much harder to heat the home," says Rich Walker, president of Summers Plumbing Heating & Cooling. This results in more energy usage and higher utility bills.
Fires Burn Out
Unlike your heater, which runs consistently throughout the day, a fire eventually burns out. "Once the fire dies down, indoor temperature can drop significantly," says Mike Conrad, co-founder and lead HVAC technician with L & M HVAC and Mechanical. "Restarting the heat system could be less efficient than keeping a steady baseline temperature."
Reduces Risk of Frozen Pipes
Turning off your heater increases your risk of frozen pipes, even when your fireplace is burning. This is especially a risk in homes with wood-burning fireplaces. "Wood fireplaces draw warm indoor air up the flue, pulling in cold outside air through cracks and gaps," says Josh Mitchell, HVAC technician and owner of Air Conditioner Lab. "If the central system is off, you lose pressure balance. That cold air often enters at exterior walls or basements, where pipes are most at risk. I've been called in to repair cracked pipes and cold rooms caused by this exact setup."
How to Run Your Heater and Fireplace Simultaneously
Our experts agree-the best course of action is to keep the heater on when your fireplace is burning. But there is a way to do so while conserving energy. "Lower the thermostat by three to four degrees while the fire is burning," says Mitchell. "That keeps background heat steady, reduces the risk of freezing, and saves energy without sacrificing coverage." If you use a programmable thermostat, set it to drop at the time you usually light a fire.
Additional Tips
Fireplaces are a great secondary heat source-but are not a replacement for central heating, says Walker. That said, there is a way to ensure these two heat sources work together while conserving energy. Our experts recommend keeping these tips in mind when using your heater and fireplace simultaneously.
- Use the fireplace for coziness: Consider lighting it for short periods to provide local heating in living spaces. Treat it as supplemental heat, not a primary source for the entire home, says Mitchell.
- Open all interior doors: Let heat from the fireplace circulate throughout your home by leaving your doors open.
- Install glass doors on your fireplace: Glass doors or a fireplace with a sealed insert will provide more consistent heat. Keep these closed when a fire is burning. "This lets the natural heat come through the glass but stops the draft from pulling air up the flue from the room," says Neil Riddoch, founder of Highlander Heating.
- Use ceiling fans: Set them to clockwise at the lowest speed to push warm air down and outward.
- Check the damper: Ensure it is completely open when using the fireplace and fully closed after use to prevent heat from escaping through the chimney.
- Maintain your HVAC system: Replace filters regularly and have a professional service your system once or twice annually to ensure it's not working against the airflow created by the chimney, Conrad says.
