Every Arizona homeowner who leaves for the summer eventually asks this. The honest answer is that it depends, and anyone who gives you a single number without asking about your house isn't giving you the full picture.
What the right setting depends on
- The property. Size, insulation, window exposure, and how many HVAC zones there are all change how hard the system works and how hot the house gets.
- The HVAC system. Age, type, and condition matter. An older system may handle a long, steady run differently than a newer one.
- Humidity. Monsoon season raises indoor humidity, and a house that isn't being cooled can hold it. Some homes also have humidity-sensitive finishes.
- Furnishings and finishes. Hardwood floors, fine cabinetry, instruments, artwork, wine, and electronics all have their own tolerances.
- Pets and plants. Anything living in the house raises the bar, and pets shouldn't be left unattended for long periods in any case.
- Insurer and manufacturer guidance. Some insurance policies have vacancy conditions, and HVAC and equipment manufacturers publish operating guidance. Read your policy and ask your HVAC contractor.
- Your own preferences. How much you want to spend on cooling an empty house is a legitimate factor.
The risks at both extremes
Setting the thermostat very high, or turning the system off, lets the house heat up well past what it's built for. A closed-up Phoenix home can climb past 100°F inside in summer. That stresses flooring, cabinetry, finishes, and electronics, and when cooling restarts after a long off period, moisture can condense on cool surfaces. Shutting the system off entirely is the setting we'd most want an owner to think twice about.
Setting it low avoids those problems but runs the equipment hard for months when no one is home, which costs money and adds wear. Most owners end up somewhere in the middle: a setting that keeps the house comfortably below its worst conditions without running the system as if someone were home. Where exactly that lands is a decision to make with your HVAC contractor, based on the factors above. Our summer departure checklist covers the rest of the preparation.
Thermostat considerations
- Use a hold or away setting that won't be overridden by a schedule designed for an occupied home.
- Replace thermostat batteries before you go if yours uses them. A dead thermostat can mean a dead system.
- Change the air filter and, if it's due, have the system serviced before a long absence rather than after a failure.
What smart thermostat alerts can and can't do
A smart thermostat that alerts you when the indoor temperature crosses a threshold is worth having. It can tell you the house is getting hot. It generally can't tell you why, and it depends on power and Wi-Fi staying up. If the thermostat goes offline, you get silence, which is easy to mistake for good news.
HVAC failure and condensate problems
An air conditioner pulls moisture out of the air, and that water has to go somewhere. If the condensate drain line clogs, the water can back up and overflow into an attic, a closet, or a ceiling. Some systems have a safety switch that shuts the unit off when that happens, which protects the house but also means the home starts warming up. Either outcome, a leak or a shutdown, can run for weeks in an empty house.
Why remote monitoring doesn't catch everything
A thermostat reads the temperature in one spot. It doesn't show water staining on a ceiling, a damp closet, a stuck drain line, a refrigerator that has stopped cooling, or a pest problem. Those only show up when someone walks through. That's the part of the job a person has to do, and it's what a Home Watch visit is for.
Where Home Watch fits
On each visit we check the thermostat and HVAC operation, look for leaks and moisture, and send a photo report, so you hear about a problem in days instead of when you get back. If you're leaving a Phoenix-area home, Home Watch in Phoenix explains how it works, the plans start at $149 a month, and an example report shows what you'd receive. Leaving Arizona for an extended period? See our Home Watch plans.