That small thermostat change could have a big impact on winter heating costs.

A homeowner with a new hybrid heating system was caught off guard after a technician adjusted the setting so the backup gas furnace would turn on below 45 degrees Fahrenheit rather than 35.

That small thermostat change could have a big impact on winter heating costs.

What to know

In a post on the Reddit forum r/heatpumps, the homeowner said the hybrid setup — a heat pump paired with a backup gas furnace — had been installed and that the air conditioning “worked like a charm.” But when they first switched to heat, a technician arrived to fix an issue and changed the switchover temperature in the process.

According to the homeowner, the technician phoned his boss and said “that it should be 45 for this system,” replacing the earlier 35-degree setting. The homeowner said they were not trying to second-guess the professionals, but still wondered whether 45 was too high, adding, “I just want to make sure I’m using my heat pump to its fullest potential.”

Many commenters said there is no single correct cutoff and that the right setting depends on the equipment and local utility prices. “You need two numbers — the cost of your electric and the cost of your nat gas,” one commenter wrote.

For homeowners trying to understand settings like a hybrid switchover, Palmetto can help explain newer, more efficient HVACs and heat pumps. Its Comfort Plan network can also connect readers with vetted installers and efficient heating and cooling solutions for their home.

More context

The cutoff setting can quietly determine how much of the winter a homeowner relies on the heat pump instead of burning gas. In this case, the adjustment happened during a service visit.

Commenters also shared how widely systems can vary from home to home. One said their cold-climate heat pump has handled temperatures down to minus 6 degrees Fahrenheit without ever using backup heat, while another said their Bosch system's emergency heat does not kick on until minus 10.

Still, some commenters said 45 degrees is not automatically the wrong choice if gas is especially cheap compared with electricity. One person in New England said their “economic cutover” for gas was in the 45-degree range. Another said they keep theirs around 40 or 45 mainly for comfort in a drafty, older home with many windows.

Setting the cutoff too high could mean using more gas than necessary, while setting it too low could raise electric costs or reduce comfort if the system is not designed for colder weather.

What can be done?

Commenters advised the homeowner to gather details such as model numbers, power rates per kilowatt-hour, gas costs per therm, and whether the heat pump is built for colder climates before changing the threshold again.

For homeowners who decide their current setup is not the best fit, Palmetto's Comfort Plan offers $0-down options that can cut heating and cooling costs by up to 50%, plus 12 years of free maintenance. That can make it easier to move to a newer system instead of guessing whether an older furnace-heat-pump balance point is costing money.

Commenters also suggested practical ways to improve performance before replacing equipment. One said better insulation helped them plan to test lower balance points after upgrading an attic from R9 to R60. Another recommended leaving the heat pump running steadily because “It takes a while to maintain that temp.”

Later in the decision process, homeowners can also pair solar panels with electric appliances, including efficient HVACs, to lower utility bills even further. EnergySage makes it easier to compare solar options and find the best solar system and installer for a home's needs and budget, and it can help homeowners save up to $10,000 on solar installations.

Where can I learn more?

Questions about hybrid heat settings can quickly lead to bigger decisions about repairs, thermostat strategy, and cold-weather performance. Related coverage includes homeowner stories about heat pump repairs, winter thermostat mistakes, expensive AC calls, and how these systems hold up during deep cold.

• One homeowner found a simple heat pump repair raised bigger questions about furnace and electric costs.

• A meteorologist warned that a common thermostat misconception can quietly drive winter heating bills higher.

• In Texas, an AC recharge spiraled from an 82-degree house into a $9.7K replacement.

• A homeowner said their trendy heat pump kept running even with 20-degree weather outside.

• During a Massachusetts cold snap, heat pump owners compared whether their systems could keep up.