Snowbird Season: Setting Up a Valley Home You Are Leaving Behind

Why you cannot just turn it off

An empty Phoenix house in July reaches interior temperatures well above 120 degrees. That is not a hypothetical — it is what an unconditioned, closed-up house does in this climate.

At those temperatures, things go wrong that have nothing to do with comfort. Adhesives in cabinetry and flooring fail. Electronics degrade. Candles, cosmetics, and some medications liquefy. Wood furniture and musical instruments crack as moisture leaves them. Drywall joints move. Paint blisters.

And during monsoon, a house with no air conditioning has no dehumidification either, so humidity climbs indoors while the temperature does. That combination is how a closed-up house develops a microbial problem.

Summer vacancy settings

• Set cooling to 85°F. Warm enough to cost relatively little, cool enough to protect the structure and contents. Do not go above 88.
• Fan on AUTO. No reason to run the blower in an empty house, and during monsoon ON works against you.
• Change the filter before you leave and again when you return.
• Flush the condensate drain with vinegar before leaving. A clog in an unoccupied house means water runs into the ceiling for weeks with nobody to notice.
• Verify the float switch works. This is the device that shuts the system off before an overflow. In a vacant house it is the only protection you have.
• Shut off the main water supply. The most common catastrophic vacant-home loss is a supply line failure, not an HVAC failure.

Winter vacancy settings

Leaving in summer and returning in winter — or the reverse — changes the picture. For a Valley home vacant in winter, set heating to about 55 to 60 degrees. That protects plumbing during the occasional freeze and keeps the house from getting damp and cold enough to cause problems.

Do not turn the heat completely off. Valley freezes are uncommon but they happen, and exterior-wall plumbing in an unheated house is a real risk on those nights.

Remote monitoring is worth it here

A connected thermostat earns its cost in a vacant Phoenix home more than in almost any other situation. Being able to see the indoor temperature from two thousand miles away, and getting an alert when it climbs past a threshold, is the difference between a service call and a disaster.

Set a high-temperature alert at around 90 degrees. If the system fails in July, you want to know that day — not in October.

Independent temperature and water sensors are inexpensive and worth adding, particularly one in the air handler drain pan and one near the water heater.

Before you leave: the full list

• Professional maintenance visit, ideally within a month of departure
• Fresh filter, and leave a spare out for whoever checks the house
• Condensate drain flushed and float switch tested
• Main water supply shut off; water heater set to vacation mode or off
• Blinds and curtains closed on every window — this makes a real difference in load
• Outdoor unit cleared of debris and vegetation
• Surge protection in place, given monsoon storms
• Someone with a key, a list of what to check, and our phone number

When you come back

Do not simply drop the thermostat to 72 and walk away. Lower it in stages over a few hours. A system starting against a 90-degree house and a superheated attic can freeze the coil if it runs continuously against a large gap while the filter and coil are less than clean.

Replace the filter, take a look at the drain pan for standing water, walk the house checking every supply register for airflow, and listen to the outdoor unit start. Anything that sounds or feels different from how you left it is worth a call before summer arrives in earnest.