The FPL bill for the Davis Shores house nobody was in all summer, and what was running while you were gone

The bill arrives in Ohio

The house in Davis Shores was shut in mid-May. Thermostat at 80, shutters closed, water off. The July bill from Florida Power & Light arrives at the owner’s summer address at nearly twice last July’s, and the kilowatt-hour chart on the second page shows the house using more power empty than it did with people in it. Nothing about the owner’s habits changed; they were not there to have habits. Something in the house was running, and running hard.

That bill is one of our most common September calls, and the list of what it might have been is short.

What runs in an empty Florida house

The air conditioner, which should cycle a few times a day to hold 80 and dry the air. The water heater, which should do almost nothing. The refrigerator. A pool pump on a timer. A dehumidifier, if there is one. And whatever was left on by accident. In a house that is working, the air conditioner is most of the bill and the pool pump is most of the rest. In a house with a problem, one of them has gone from a few hours a day to all of them.

The suspects, from biggest draw to smallest

1. Electric heat strips running during cooling. A stuck sequencer or relay in the air handler energizes the strips while the compressor runs. The system cools and heats at the same time, around the clock. The biggest single jump we find.
2. A compressor on its way out. Worn valves and bearings pull far more current than the nameplate says, for less cooling. Amps tell the story in a minute.
3. A refrigerant leak. The system runs continuously trying to reach a setpoint it can hold for only a few minutes at a time. Common on coastal coils in Davis Shores and across the island.
4. A dirty or salt-crusted outdoor coil. The unit cannot shed heat, so it runs longer and hotter. Common on any bayfront address that has not had a rinse in a year.
5. A pool pump timer stuck on. Not the AC at all, and worth ruling out before any AC part is sold.
6. Leaking ductwork. A return pulling 130-degree attic air, or a supply dumping cold air into the attic, forces hours of extra runtime. The 2000s flex duct in World Golf Village and Murabella is reaching the age where this starts.
7. A thermostat that lost its program. A power blip resets it to a factory schedule, and 80 becomes 72.

How we find it with a clamp meter and a runtime log

We measure current at the outdoor unit and compare it to the nameplate. We measure at the air handler to see whether the strips are drawing power when they should be dead. We check refrigerant pressures and the coil condition. And we look at runtime: a smart thermostat’s history, or a day of watching the cycles, shows whether the system is running 40 percent of the hours or 95. The combination identifies the cause in one visit, and the price of the fix comes before the fix does.

Ask for a bill diagnosis

Before we come: three things to check from your phone

If the house has a connected thermostat, look at its runtime history for the month; a flat line at 100 percent is the answer. Look at the FPL account’s daily usage chart, which shows the day the jump started, often the day a storm rolled through. And ask whoever checks the house to stand at the air handler for a minute while it runs: a warm cabinet during cooling, or hot air from the registers, means the strips are on. Any of those three turns a vague bill complaint into a specific repair, and we can often bring the right part on the first trip.