Away from home: HVAC settings for vacations and second homes

The winter setback, and why not lower

Around 55°F is the long-standing guidance for an empty home in winter, and it earns its place for two reasons. First, plumbing: pipes in exterior walls and crawlspaces see temperatures well below what the thermostat reads, so the margin matters more than it looks. Second — and this is the Northwest-specific part — surface temperatures. A house held in the mid-fifties keeps window frames, closet walls, and corners warm enough that ordinary indoor moisture doesn't condense on them. Let the house drift into the forties for weeks and every cold surface becomes a condensation collector, which is how owners come home to weeping windows, musty closets, and mildew blooms.

The mold math of an empty PNW house

Occupied homes fight dampness constantly without noticing: heating cycles, opened doors, bath fans, moving air. An empty winter house loses all of that. The air goes still, surfaces go cold, and outdoor humidity — which sits high here from October through April — works on the envelope for weeks uninterrupted. Mold needs moisture, mild temperatures, and time, and an unconditioned vacant house supplies all three. Steady low heat is the countermeasure: it keeps surfaces above the dew point and induces gentle air movement. For chronically damp lower levels, a standalone dehumidifier with a drain hose, set to hold roughly 50% relative humidity, is a worthwhile companion to the heating setback.

Summer away is easier, with one caveat

Summer vacancy is more forgiving — our overnight lows do a lot of free cooling — but fully off still isn't ideal. A closed-up house in a heat wave soaks heat into its structure for days, stressing everything from houseplants to electronics, and takes a long, hard recovery run when you return. A cooling hold in the low 80s prevents heat-soak cheaply. The caveat is smoke season: if a wildfire smoke event rolls through while you're away, a sealed house with the fan set to AUTO mostly protects itself, but check remotely if you can, and change the filter when you get home if the region had smoky days.

Smart controls: the remote check-in

A connected thermostat turns 'hope the house is fine' into a ten-second phone check. You can confirm the hold temperature, see if the system is keeping up, and get alerts if the temperature falls outside a range you set — which is often the first sign of a failed system, a power outage, or a door that didn't latch. Some models add remote sensors for humidity or for a vulnerable spot like a pump room. For second homes and rentals, that alerting is the difference between a service call and an insurance claim. If you travel regularly, tell us during a tune-up — we can confirm your thermostat's away features and set the schedules up properly.

Common questions