For most homes with a gas furnace and central air that share an air handler or furnace cabinet, leave electrical power to the furnace or air handler on for the summer, and set the thermostat to Cool. Shutting everything down is rarely required and can create confusion when you need heat again.
What you should do
- Set the thermostat to Cool (or Off if you will be away and the house can stay warm safely).
- Leave power to the furnace or air handler on so the blower can run the air conditioner.
- Leave the gas valve on unless a technician asks you to shut it for a specific repair.
- Change filters on the schedule your filter and equipment makers recommend. Summer dust still loads the same filter path.
When shutting gas off makes sense
If you smell gas, hear hissing near the furnace, or a technician finds a leak, shut the gas at the appliance valve if you can do so safely and call for service. Long vacancies are a separate household decision about the meter or main shutoff, not a summer furnace tip by itself.
Before the first cold snap
Schedule heating maintenance so ignition, safeties, and airflow get checked before you need heat. See also furnace services or call 908-752-0234.