Closing up the house for a week of summer vacation feels like the responsible move — turn the thermostat up, save some money, come home to a clean house. The setting matters more than most people realize.
Your central air system does two jobs at once: it cools the air, and it pulls moisture out of it. Set the thermostat too high while you’re away — above roughly 85 degrees — and the AC may not run often enough to keep humidity under control, even though the space just feels “off” rather than uncomfortably hot. That’s enough for moisture to build in carpets, closets, and closed-up rooms while nobody’s there to notice.
General health guidance recommends keeping indoor humidity at or below 50 percent, and mold spores can begin settling into damp material in as little as 24 to 48 hours under favorable conditions. A week-long trip is more than enough time for that window to close.
Most guidance lands in the same range: keep the thermostat somewhere between 78 and 85 degrees while away rather than shutting the system off completely, and keep blinds and curtains closed to reduce heat gain. If your thermostat controls humidity separately from temperature, setting it to the 30–50 percent range gives the system a clearer target.
Coming home to a musty smell that wasn’t there before you left is worth a closer look before you unpack.
By the numbers:
- Recommended vacation thermostat range: 78–85°F — never fully off.
- Indoor humidity should stay at or below 50%, per general health guidance.
- Mold spores can begin settling into damp materials within 24–48 hours under favorable conditions.
Sources: HVAC industry guidance on vacation thermostat settings; general public health indoor humidity guidance
A thermostat adjustment is a simple fix going forward, but if you’re already noticing a musty smell after a trip, an assessment tells you whether it’s just stale air or something that needs attention. Call 888-609-6653 or visit RamMoldPro.com to schedule a consultation.
